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<front> <front>
<title>Using TLS to Secure QUIC</title> <title>Using TLS to Secure QUIC</title>
<seriesInfo name="Internet-Draft" value="draft-ietf-quic-tls-34"/> <seriesInfo name="RFC" value="9001"/>
<author initials="M." surname="Thomson" fullname="Martin Thomson" role="edit or"> <author initials="M." surname="Thomson" fullname="Martin Thomson" role="edit or">
<organization>Mozilla</organization> <organization>Mozilla</organization>
<address> <address>
<email>mt@lowentropy.net</email> <email>mt@lowentropy.net</email>
</address> </address>
</author> </author>
<author initials="S." surname="Turner" fullname="Sean Turner" role="editor"> <author initials="S." surname="Turner" fullname="Sean Turner" role="editor">
<organization>sn3rd</organization> <organization>sn3rd</organization>
<address> <address>
<email>sean@sn3rd.com</email> <email>sean@sn3rd.com</email>
</address> </address>
</author> </author>
<date year="2021" month="January" day="15"/> <date year="2021" month="May"/>
<area>Transport</area> <area>Transport</area>
<workgroup>QUIC</workgroup> <workgroup>QUIC</workgroup>
<keyword>crypto</keyword>
<keyword>opportunistic encryption</keyword>
<keyword>plaintext quic</keyword>
<abstract> <abstract>
<t>This document describes how Transport Layer Security (TLS) is used to s ecure <t>This document describes how Transport Layer Security (TLS) is used to s ecure
QUIC.</t> QUIC.</t>
</abstract> </abstract>
<note>
<name>Note to Readers</name>
<t>Discussion of this draft takes place on the QUIC working group mailing
list
(quic@ietf.org), which is archived at
<eref target="https://mailarchive.ietf.org/arch/search/?email_list=quic"/>.</t>
<t>Working Group information can be found at <eref target="https://github.
com/quicwg"/>; source
code and issues list for this draft can be found at
<eref target="https://github.com/quicwg/base-drafts/labels/-tls"/>.</t>
</note>
</front> </front>
<middle> <middle>
<section anchor="introduction" numbered="true" toc="default"> <section anchor="introduction" numbered="true" toc="default">
<name>Introduction</name> <name>Introduction</name>
<t>This document describes how QUIC <xref target="QUIC-TRANSPORT" format=" default"/> is secured using TLS <t>This document describes how QUIC <xref target="QUIC-TRANSPORT" format=" default"/> is secured using TLS
<xref target="TLS13" format="default"/>.</t> <xref target="TLS13" format="default"/>.</t>
<t>TLS 1.3 provides critical latency improvements for connection establish ment over <t>TLS 1.3 provides critical latency improvements for connection establish ment over
previous versions. Absent packet loss, most new connections can be established previous versions. Absent packet loss, most new connections can be established
and secured within a single round trip; on subsequent connections between the and secured within a single round trip; on subsequent connections between the
same client and server, the client can often send application data immediately, same client and server, the client can often send application data immediately,
that is, using a zero round trip setup.</t> that is, using a zero round-trip setup.</t>
<t>This document describes how TLS acts as a security component of QUIC.</ t> <t>This document describes how TLS acts as a security component of QUIC.</ t>
</section> </section>
<section anchor="notational-conventions" numbered="true" toc="default"> <section anchor="notational-conventions" numbered="true" toc="default">
<name>Notational Conventions</name> <name>Notational Conventions</name>
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL <t>The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", >REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>
"MAY", and "OPTIONAL" in this document are to be interpreted as SHOULD</bcp14>",
described in BCP&nbsp;14 <xref target="RFC2119" format="default"/> <xref target= "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMEND
"RFC8174" format="default"/> when, and only when, they ED</bcp14>", "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this
appear in all capitals, as shown here.</t> document are to be interpreted as described in BCP 14 <xref target="RFC2119" for
mat="default"/> <xref target="RFC8174" format="default"/>
when, and only when, they appear in all capitals, as shown here.</t>
<t>This document uses the terminology established in <xref target="QUIC-TR ANSPORT" format="default"/>.</t> <t>This document uses the terminology established in <xref target="QUIC-TR ANSPORT" format="default"/>.</t>
<t>For brevity, the acronym TLS is used to refer to TLS 1.3, though a newe r version <t>For brevity, the acronym TLS is used to refer to TLS 1.3, though a newe r version
could be used; see <xref target="tls-version" format="default"/>.</t> could be used; see <xref target="tls-version" format="default"/>.</t>
<section anchor="tls-overview" numbered="true" toc="default"> <section anchor="tls-overview" numbered="true" toc="default">
<name>TLS Overview</name> <name>TLS Overview</name>
<t>TLS provides two endpoints with a way to establish a means of communi cation over <t>TLS provides two endpoints with a way to establish a means of communi cation over
an untrusted medium (for example, the Internet). TLS enables authentication of an untrusted medium (for example, the Internet). TLS enables authentication of
peers and provides confidentiality and integrity protection for messages that peers and provides confidentiality and integrity protection for messages that
endpoints exchange.</t> endpoints exchange.</t>
<t>Internally, TLS is a layered protocol, with the structure shown in <t>Internally, TLS is a layered protocol, with the structure shown in
skipping to change at line 87 skipping to change at line 73
Content | | | Application | | Content | | | Application | |
Layer | Handshake | Alerts | Data | ... | Layer | Handshake | Alerts | Data | ... |
| | | | | | | | | |
+-------------+------------+--------------+---------+ +-------------+------------+--------------+---------+
Record | | Record | |
Layer | Records | Layer | Records |
| | | |
+---------------------------------------------------+ +---------------------------------------------------+
]]></artwork> ]]></artwork>
</figure> </figure>
<t>Each Content layer message (e.g., Handshake, Alerts, and Application <t>Each content-layer message (e.g., handshake, alerts, and application
Data) is data) is
carried as a series of typed TLS records by the Record layer. Records are carried as a series of typed TLS records by the record layer. Records are
individually cryptographically protected and then transmitted over a reliable individually cryptographically protected and then transmitted over a reliable
transport (typically TCP), which provides sequencing and guaranteed delivery.</t > transport (typically TCP), which provides sequencing and guaranteed delivery.</t >
<t>The TLS authenticated key exchange occurs between two endpoints: clie nt and <t>The TLS authenticated key exchange occurs between two endpoints: clie nt and
server. The client initiates the exchange and the server responds. If the key server. The client initiates the exchange and the server responds. If the key
exchange completes successfully, both client and server will agree on a secret. exchange completes successfully, both client and server will agree on a secret.
TLS supports both pre-shared key (PSK) and Diffie-Hellman over either finite TLS supports both pre-shared key (PSK) and Diffie-Hellman over either finite
fields or elliptic curves ((EC)DHE) key exchanges. PSK is the basis for Early fields or elliptic curves ((EC)DHE) key exchanges. PSK is the basis for Early
Data (0-RTT); the latter provides forward secrecy (FS) when the (EC)DHE Data (0-RTT); the latter provides forward secrecy (FS) when the (EC)DHE
keys are destroyed. The two modes can also be combined, to provide forward keys are destroyed. The two modes can also be combined to provide forward
secrecy while using the PSK for authentication.</t> secrecy while using the PSK for authentication.</t>
<t>After completing the TLS handshake, the client will have learned and <t>After completing the TLS handshake, the client will have learned and
authenticated an identity for the server and the server is optionally able to authenticated an identity for the server, and the server is optionally able to
learn and authenticate an identity for the client. TLS supports X.509 learn and authenticate an identity for the client. TLS supports X.509
<xref target="RFC5280" format="default"/> certificate-based authentication for b oth server and client. <xref target="RFC5280" format="default"/> certificate-based authentication for b oth server and client.
When PSK key exchange is used (as in resumption), knowledge of the PSK When PSK key exchange is used (as in resumption), knowledge of the PSK
serves to authenticate the peer.</t> serves to authenticate the peer.</t>
<t>The TLS key exchange is resistant to tampering by attackers and it pr oduces <t>The TLS key exchange is resistant to tampering by attackers, and it p roduces
shared secrets that cannot be controlled by either participating peer.</t> shared secrets that cannot be controlled by either participating peer.</t>
<t>TLS provides two basic handshake modes of interest to QUIC:</t> <t>TLS provides two basic handshake modes of interest to QUIC:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>A full 1-RTT handshake, in which the client is able to send Applic ation Data <li>A full 1-RTT handshake, in which the client is able to send applic ation data
after one round trip and the server immediately responds after receiving the after one round trip and the server immediately responds after receiving the
first handshake message from the client.</li> first handshake message from the client.</li>
<li>A 0-RTT handshake, in which the client uses information it has pre viously <li>A 0-RTT handshake, in which the client uses information it has pre viously
learned about the server to send Application Data immediately. This learned about the server to send application data immediately. This
Application Data can be replayed by an attacker so 0-RTT is not suitable for application data can be replayed by an attacker, so 0-RTT is not suitable for
carrying instructions that might initiate any action that could cause carrying instructions that might initiate any action that could cause
unwanted effects if replayed.</li> unwanted effects if replayed.</li>
</ul> </ul>
<t>A simplified TLS handshake with 0-RTT application data is shown in <x ref target="tls-full" format="default"/>.</t> <t>A simplified TLS handshake with 0-RTT application data is shown in <x ref target="tls-full" format="default"/>.</t>
<figure anchor="tls-full"> <figure anchor="tls-full">
<name>TLS Handshake with 0-RTT</name> <name>TLS Handshake with 0-RTT</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
Client Server Client Server
ClientHello ClientHello
skipping to change at line 146 skipping to change at line 132
[] Indicates messages protected using Application Data [] Indicates messages protected using Application Data
(1-RTT) Keys (1-RTT) Keys
]]></artwork> ]]></artwork>
</figure> </figure>
<t><xref target="tls-full" format="default"/> omits the EndOfEarlyData m essage, which is not used in QUIC; see <t><xref target="tls-full" format="default"/> omits the EndOfEarlyData m essage, which is not used in QUIC; see
<xref target="remove-eoed" format="default"/>. Likewise, neither ChangeCipherSpe c nor KeyUpdate messages are <xref target="remove-eoed" format="default"/>. Likewise, neither ChangeCipherSpe c nor KeyUpdate messages are
used by QUIC. ChangeCipherSpec is redundant in TLS 1.3; see <xref target="compat -mode" format="default"/>. used by QUIC. ChangeCipherSpec is redundant in TLS 1.3; see <xref target="compat -mode" format="default"/>.
QUIC has its own key update mechanism; see <xref target="key-update" format="def ault"/>.</t> QUIC has its own key update mechanism; see <xref target="key-update" format="def ault"/>.</t>
<t>Data is protected using a number of encryption levels:</t> <t>Data is protected using a number of encryption levels:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>Initial Keys</li> <li>Initial keys</li>
<li>Early Data (0-RTT) Keys</li> <li>Early data (0-RTT) keys</li>
<li>Handshake Keys</li> <li>Handshake keys</li>
<li>Application Data (1-RTT) Keys</li> <li>Application data (1-RTT) keys</li>
</ul> </ul>
<t>Application Data may appear only in the Early Data and Application Da <t>Application data can only appear in the early data and application da
ta ta
levels. Handshake and Alert messages may appear in any level.</t> levels. Handshake and alert messages may appear in any level.</t>
<t>The 0-RTT handshake can be used if the client and server have previou sly <t>The 0-RTT handshake can be used if the client and server have previou sly
communicated. In the 1-RTT handshake, the client is unable to send protected communicated. In the 1-RTT handshake, the client is unable to send protected
Application Data until it has received all of the Handshake messages sent by the application data until it has received all of the handshake messages sent by the
server.</t> server.</t>
</section> </section>
</section> </section>
<section anchor="protocol-overview" numbered="true" toc="default"> <section anchor="protocol-overview" numbered="true" toc="default">
<name>Protocol Overview</name> <name>Protocol Overview</name>
<t>QUIC <xref target="QUIC-TRANSPORT" format="default"/> assumes responsib ility for the confidentiality and <t>QUIC <xref target="QUIC-TRANSPORT" format="default"/> assumes responsib ility for the confidentiality and
integrity protection of packets. For this it uses keys derived from a TLS integrity protection of packets. For this it uses keys derived from a TLS
handshake <xref target="TLS13" format="default"/>, but instead of carrying TLS r ecords over QUIC (as with handshake <xref target="TLS13" format="default"/>, but instead of carrying TLS r ecords over QUIC (as with
TCP), TLS Handshake and Alert messages are carried directly over the QUIC TCP), TLS handshake and alert messages are carried directly over the QUIC
transport, which takes over the responsibilities of the TLS record layer, as transport, which takes over the responsibilities of the TLS record layer, as
shown in <xref target="quic-layers" format="default"/>.</t> shown in <xref target="quic-layers" format="default"/>.</t>
<figure anchor="quic-layers"> <figure anchor="quic-layers">
<name>QUIC Layers</name> <name>QUIC Layers</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
+--------------+--------------+ +-------------+ +--------------+--------------+ +-------------+
| TLS | TLS | | QUIC | | TLS | TLS | | QUIC |
| Handshake | Alerts | | Applications| | Handshake | Alerts | | Applications|
| | | | (h3, etc.) | | | | | (h3, etc.) |
+--------------+--------------+-+-------------+ +--------------+--------------+-+-------------+
skipping to change at line 197 skipping to change at line 183
are critical to security and performance.</t> are critical to security and performance.</t>
<t>Rather than a strict layering, these two protocols cooperate: QUIC uses the TLS <t>Rather than a strict layering, these two protocols cooperate: QUIC uses the TLS
handshake; TLS uses the reliability, ordered delivery, and record layer provided handshake; TLS uses the reliability, ordered delivery, and record layer provided
by QUIC.</t> by QUIC.</t>
<t>At a high level, there are two main interactions between the TLS and QU IC <t>At a high level, there are two main interactions between the TLS and QU IC
components:</t> components:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>The TLS component sends and receives messages via the QUIC component , with <li>The TLS component sends and receives messages via the QUIC component , with
QUIC providing a reliable stream abstraction to TLS.</li> QUIC providing a reliable stream abstraction to TLS.</li>
<li>The TLS component provides a series of updates to the QUIC component , <li>The TLS component provides a series of updates to the QUIC component ,
including (a) new packet protection keys to install (b) state changes such as including (a) new packet protection keys to install and (b) state changes such
handshake completion, the server certificate, etc.</li> as handshake completion, the server certificate, etc.</li>
</ul> </ul>
<t><xref target="schematic" format="default"/> shows these interactions in more detail, with the QUIC packet <t><xref target="schematic" format="default"/> shows these interactions in more detail, with the QUIC packet
protection being called out specially.</t> protection being called out specially.</t>
<figure anchor="schematic"> <figure anchor="schematic">
<name>QUIC and TLS Interactions</name> <name>QUIC and TLS Interactions</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
+------------+ +------------+ +------------+ +------------+
| |<---- Handshake Messages ----->| | | |<---- Handshake Messages ----->| |
| |<- Validate 0-RTT parameters ->| | | |<- Validate 0-RTT Parameters ->| |
| |<--------- 0-RTT Keys ---------| | | |<--------- 0-RTT Keys ---------| |
| QUIC |<------- Handshake Keys -------| TLS | | QUIC |<------- Handshake Keys -------| TLS |
| |<--------- 1-RTT Keys ---------| | | |<--------- 1-RTT Keys ---------| |
| |<------- Handshake Done -------| | | |<------- Handshake Done -------| |
+------------+ +------------+ +------------+ +------------+
| ^ | ^
| Protect | Protected | Protect | Protected
v | Packet v | Packet
+------------+ +------------+
| QUIC | | QUIC |
| Packet | | Packet |
| Protection | | Protection |
+------------+ +------------+
]]></artwork> ]]></artwork>
</figure> </figure>
<t>Unlike TLS over TCP, QUIC applications that want to send data do not se nd it <t>Unlike TLS over TCP, QUIC applications that want to send data do not se nd it
through TLS "application_data" records. Rather, they send it as QUIC STREAM using TLS Application Data records. Rather, they send it as QUIC STREAM
frames or other frame types, which are then carried in QUIC packets.</t> frames or other frame types, which are then carried in QUIC packets.</t>
</section> </section>
<section anchor="carrying-tls" numbered="true" toc="default"> <section anchor="carrying-tls" numbered="true" toc="default">
<name>Carrying TLS Messages</name> <name>Carrying TLS Messages</name>
<t>QUIC carries TLS handshake data in CRYPTO frames, each of which consist s of a <t>QUIC carries TLS handshake data in CRYPTO frames, each of which consist s of a
contiguous block of handshake data identified by an offset and length. Those contiguous block of handshake data identified by an offset and length. Those
frames are packaged into QUIC packets and encrypted under the current frames are packaged into QUIC packets and encrypted under the current
encryption level. As with TLS over TCP, once TLS handshake data has been encryption level. As with TLS over TCP, once TLS handshake data has been
delivered to QUIC, it is QUIC's responsibility to deliver it reliably. Each delivered to QUIC, it is QUIC's responsibility to deliver it reliably. Each
chunk of data that is produced by TLS is associated with the set of keys that chunk of data that is produced by TLS is associated with the set of keys that
TLS is currently using. If QUIC needs to retransmit that data, it MUST use the TLS is currently using. If QUIC needs to retransmit that data, it <bcp14>MUST</ bcp14> use the
same keys even if TLS has already updated to newer keys.</t> same keys even if TLS has already updated to newer keys.</t>
<t>Each encryption level corresponds to a packet number space. The packet <t>Each encryption level corresponds to a packet number space. The packet
number number
space that is used determines the semantics of frames. Some frames are space that is used determines the semantics of frames. Some frames are
prohibited in different packet number spaces; see Section 12.5 of prohibited in different packet number spaces; see <xref section="12.5" sectionFo
<xref target="QUIC-TRANSPORT" format="default"/>.</t> rmat="of" target="QUIC-TRANSPORT" format="default"/>.</t>
<t>Because packets could be reordered on the wire, QUIC uses the packet ty pe to <t>Because packets could be reordered on the wire, QUIC uses the packet ty pe to
indicate which keys were used to protect a given packet, as shown in indicate which keys were used to protect a given packet, as shown in
<xref target="packet-types-keys" format="default"/>. When packets of different t ypes need to be sent, <xref target="packet-types-keys" format="default"/>. When packets of different t ypes need to be sent,
endpoints SHOULD use coalesced packets to send them in the same UDP datagram.</t > endpoints <bcp14>SHOULD</bcp14> use coalesced packets to send them in the same U DP datagram.</t>
<table anchor="packet-types-keys" align="center"> <table anchor="packet-types-keys" align="center">
<name>Encryption Keys by Packet Type</name> <name>Encryption Keys by Packet Type</name>
<thead> <thead>
<tr> <tr>
<th align="left">Packet Type</th> <th>Packet Type</th>
<th align="left">Encryption Keys</th> <th>Encryption Keys</th>
<th align="left">PN Space</th> <th>PN Space</th>
</tr> </tr>
</thead> </thead>
<tbody> <tbody>
<tr> <tr>
<td align="left">Initial</td> <th>Initial</th>
<td align="left">Initial secrets</td> <td>Initial secrets</td>
<td align="left">Initial</td> <td>Initial</td>
</tr> </tr>
<tr> <tr>
<td align="left">0-RTT Protected</td> <th>0-RTT Protected</th>
<td align="left">0-RTT</td> <td>0-RTT</td>
<td align="left">Application data</td> <td>Application data</td>
</tr> </tr>
<tr> <tr>
<td align="left">Handshake</td> <th>Handshake</th>
<td align="left">Handshake</td> <td>Handshake</td>
<td align="left">Handshake</td> <td>Handshake</td>
</tr> </tr>
<tr> <tr>
<td align="left">Retry</td> <th>Retry</th>
<td align="left">Retry</td> <td>Retry</td>
<td align="left">N/A</td> <td>N/A</td>
</tr> </tr>
<tr> <tr>
<td align="left">Version Negotiation</td> <th>Version Negotiation</th>
<td align="left">N/A</td> <td>N/A</td>
<td align="left">N/A</td> <td>N/A</td>
</tr> </tr>
<tr> <tr>
<td align="left">Short Header</td> <th>Short Header</th>
<td align="left">1-RTT</td> <td>1-RTT</td>
<td align="left">Application data</td> <td>Application data</td>
</tr> </tr>
</tbody> </tbody>
</table> </table>
<t>Section 17 of <xref target="QUIC-TRANSPORT" format="default"/> shows ho w packets at the various encryption <t><xref section="17" sectionFormat="of" target="QUIC-TRANSPORT" format="d efault"/> shows how packets at the various encryption
levels fit into the handshake process.</t> levels fit into the handshake process.</t>
<section anchor="interface-to-tls" numbered="true" toc="default"> <section anchor="interface-to-tls" numbered="true" toc="default">
<name>Interface to TLS</name> <name>Interface to TLS</name>
<t>As shown in <xref target="schematic" format="default"/>, the interfac e from QUIC to TLS consists of four <t>As shown in <xref target="schematic" format="default"/>, the interfac e from QUIC to TLS consists of four
primary functions:</t> primary functions:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>Sending and receiving handshake messages</li> <li>Sending and receiving handshake messages</li>
<li>Processing stored transport and application state from a resumed s ession <li>Processing stored transport and application state from a resumed s ession
and determining if it is valid to generate or accept early data</li> and determining if it is valid to generate or accept 0-RTT data</li>
<li>Rekeying (both transmit and receive)</li> <li>Rekeying (both transmit and receive)</li>
<li>Handshake state updates</li> <li>Updating handshake state</li>
</ul> </ul>
<t>Additional functions might be needed to configure TLS. In particular , QUIC and <t>Additional functions might be needed to configure TLS. In particular , QUIC and
TLS need to agree on which is responsible for validation of peer credentials, TLS need to agree on which is responsible for validation of peer credentials,
such as certificate validation (<xref target="RFC5280" format="default"/>).</t> such as certificate validation <xref target="RFC5280" format="default"/>.</t>
<section anchor="handshake-complete" numbered="true" toc="default"> <section anchor="handshake-complete" numbered="true" toc="default">
<name>Handshake Complete</name> <name>Handshake Complete</name>
<t>In this document, the TLS handshake is considered complete when the TLS stack <t>In this document, the TLS handshake is considered complete when the TLS stack
has reported that the handshake is complete. This happens when the TLS stack has reported that the handshake is complete. This happens when the TLS stack
has both sent a Finished message and verified the peer's Finished message. has both sent a Finished message and verified the peer's Finished message.
Verifying the peer's Finished provides the endpoints with an assurance that Verifying the peer's Finished message provides the endpoints with an assurance
previous handshake messages have not been modified. Note that the handshake that previous handshake messages have not been modified. Note that the
does not complete at both endpoints simultaneously. Consequently, any handshake does not complete at both endpoints simultaneously. Consequently, any
requirement that is based on the completion of the handshake depends on the requirement that is based on the completion of the handshake depends on the
perspective of the endpoint in question.</t> perspective of the endpoint in question.</t>
</section> </section>
<section anchor="handshake-confirmed" numbered="true" toc="default"> <section anchor="handshake-confirmed" numbered="true" toc="default">
<name>Handshake Confirmed</name> <name>Handshake Confirmed</name>
<t>In this document, the TLS handshake is considered confirmed at the server when <t>In this document, the TLS handshake is considered confirmed at the server when
the handshake completes. The server MUST send a HANDSHAKE_DONE frame as soon as the handshake completes. The server <bcp14>MUST</bcp14> send a HANDSHAKE_DONE f rame as soon as
the handshake is complete. At the client, the handshake is considered confirmed the handshake is complete. At the client, the handshake is considered confirmed
when a HANDSHAKE_DONE frame is received.</t> when a HANDSHAKE_DONE frame is received.</t>
<t>Additionally, a client MAY consider the handshake to be confirmed w hen it <t>Additionally, a client <bcp14>MAY</bcp14> consider the handshake to be confirmed when it
receives an acknowledgment for a 1-RTT packet. This can be implemented by receives an acknowledgment for a 1-RTT packet. This can be implemented by
recording the lowest packet number sent with 1-RTT keys, and comparing it to the recording the lowest packet number sent with 1-RTT keys and comparing it to the
Largest Acknowledged field in any received 1-RTT ACK frame: once the latter is Largest Acknowledged field in any received 1-RTT ACK frame: once the latter is
greater than or equal to the former, the handshake is confirmed.</t> greater than or equal to the former, the handshake is confirmed.</t>
</section> </section>
<section anchor="sending-and-receiving-handshake-messages" numbered="tru e" toc="default"> <section anchor="sending-and-receiving-handshake-messages" numbered="tru e" toc="default">
<name>Sending and Receiving Handshake Messages</name> <name>Sending and Receiving Handshake Messages</name>
<t>In order to drive the handshake, TLS depends on being able to send and receive <t>In order to drive the handshake, TLS depends on being able to send and receive
handshake messages. There are two basic functions on this interface: one where handshake messages. There are two basic functions on this interface: one where
QUIC requests handshake messages and one where QUIC provides bytes that comprise QUIC requests handshake messages and one where QUIC provides bytes that comprise
handshake messages.</t> handshake messages.</t>
<t>Before starting the handshake QUIC provides TLS with the transport parameters <t>Before starting the handshake, QUIC provides TLS with the transport parameters
(see <xref target="quic_parameters" format="default"/>) that it wishes to carry. </t> (see <xref target="quic_parameters" format="default"/>) that it wishes to carry. </t>
<t>A QUIC client starts TLS by requesting TLS handshake bytes from TLS . The client <t>A QUIC client starts TLS by requesting TLS handshake bytes from TLS . The client
acquires handshake bytes before sending its first packet. A QUIC server starts acquires handshake bytes before sending its first packet. A QUIC server starts
the process by providing TLS with the client's handshake bytes.</t> the process by providing TLS with the client's handshake bytes.</t>
<t>At any time, the TLS stack at an endpoint will have a current sendi <t>At any time, the TLS stack at an endpoint will have a current sendi
ng ng encryption
encryption level and receiving encryption level. TLS encryption levels determine level and a receiving encryption level. TLS encryption levels determine the QUIC
the QUIC packet type and keys that are used for protecting data.</t> packet type and keys that are used for protecting data.</t>
<t>Each encryption level is associated with a different sequence of by tes, which is <t>Each encryption level is associated with a different sequence of by tes, which is
reliably transmitted to the peer in CRYPTO frames. When TLS provides handshake reliably transmitted to the peer in CRYPTO frames. When TLS provides handshake
bytes to be sent, they are appended to the handshake bytes for the current bytes to be sent, they are appended to the handshake bytes for the current
encryption level. The encryption level then determines the type of packet that encryption level. The encryption level then determines the type of packet that
the resulting CRYPTO frame is carried in; see <xref target="packet-types-keys" f ormat="default"/>.</t> the resulting CRYPTO frame is carried in; see <xref target="packet-types-keys" f ormat="default"/>.</t>
<t>Four encryption levels are used, producing keys for Initial, 0-RTT, Handshake, <t>Four encryption levels are used, producing keys for Initial, 0-RTT, Handshake,
and 1-RTT packets. CRYPTO frames are carried in just three of these levels, and 1-RTT packets. CRYPTO frames are carried in just three of these levels,
omitting the 0-RTT level. These four levels correspond to three packet number omitting the 0-RTT level. These four levels correspond to three packet number
spaces: Initial and Handshake encrypted packets use their own separate spaces; spaces: Initial and Handshake encrypted packets use their own separate spaces;
0-RTT and 1-RTT packets use the application data packet number space.</t> 0-RTT and 1-RTT packets use the application data packet number space.</t>
skipping to change at line 365 skipping to change at line 350
alerts are turned into QUIC CONNECTION_CLOSE error codes; see <xref target="tls- errors" format="default"/>. alerts are turned into QUIC CONNECTION_CLOSE error codes; see <xref target="tls- errors" format="default"/>.
TLS application data and other content types cannot be carried by QUIC at any TLS application data and other content types cannot be carried by QUIC at any
encryption level; it is an error if they are received from the TLS stack.</t> encryption level; it is an error if they are received from the TLS stack.</t>
<t>When an endpoint receives a QUIC packet containing a CRYPTO frame f rom the <t>When an endpoint receives a QUIC packet containing a CRYPTO frame f rom the
network, it proceeds as follows:</t> network, it proceeds as follows:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>If the packet uses the current TLS receiving encryption level, s equence the <li>If the packet uses the current TLS receiving encryption level, s equence the
data into the input flow as usual. As with STREAM frames, the offset is used data into the input flow as usual. As with STREAM frames, the offset is used
to find the proper location in the data sequence. If the result of this to find the proper location in the data sequence. If the result of this
process is that new data is available, then it is delivered to TLS in order.</li > process is that new data is available, then it is delivered to TLS in order.</li >
<li>If the packet is from a previously installed encryption level, i t MUST NOT <li>If the packet is from a previously installed encryption level, i t <bcp14>MUST NOT</bcp14>
contain data that extends past the end of previously received data in that contain data that extends past the end of previously received data in that
flow. Implementations MUST treat any violations of this requirement as a flow. Implementations <bcp14>MUST</bcp14> treat any violations of this requireme nt as a
connection error of type PROTOCOL_VIOLATION.</li> connection error of type PROTOCOL_VIOLATION.</li>
<li>If the packet is from a new encryption level, it is saved for la ter processing <li>If the packet is from a new encryption level, it is saved for la ter processing
by TLS. Once TLS moves to receiving from this encryption level, saved data by TLS. Once TLS moves to receiving from this encryption level, saved data
can be provided to TLS. When TLS provides keys for a higher encryption level, can be provided to TLS. When TLS provides keys for a higher encryption level,
if there is data from a previous encryption level that TLS has not consumed, if there is data from a previous encryption level that TLS has not consumed,
this MUST be treated as a connection error of type PROTOCOL_VIOLATION.</li> this <bcp14>MUST</bcp14> be treated as a connection error of type PROTOCOL_VIOLA TION.</li>
</ul> </ul>
<t>Each time that TLS is provided with new data, new handshake bytes a re requested <t>Each time that TLS is provided with new data, new handshake bytes a re requested
from TLS. TLS might not provide any bytes if the handshake messages it has from TLS. TLS might not provide any bytes if the handshake messages it has
received are incomplete or it has no data to send.</t> received are incomplete or it has no data to send.</t>
<t>The content of CRYPTO frames might either be processed incrementall y by TLS or <t>The content of CRYPTO frames might either be processed incrementall y by TLS or
buffered until complete messages or flights are available. TLS is responsible buffered until complete messages or flights are available. TLS is responsible
for buffering handshake bytes that have arrived in order. QUIC is responsible for buffering handshake bytes that have arrived in order. QUIC is responsible
for buffering handshake bytes that arrive out of order or for encryption levels for buffering handshake bytes that arrive out of order or for encryption levels
that are not yet ready. QUIC does not provide any means of flow control for that are not yet ready. QUIC does not provide any means of flow control for
CRYPTO frames; see Section 7.5 of <xref target="QUIC-TRANSPORT" format="default" />.</t> CRYPTO frames; see <xref section="7.5" sectionFormat="of" target="QUIC-TRANSPORT " format="default"/>.</t>
<t>Once the TLS handshake is complete, this is indicated to QUIC along with any <t>Once the TLS handshake is complete, this is indicated to QUIC along with any
final handshake bytes that TLS needs to send. At this stage, the transport final handshake bytes that TLS needs to send. At this stage, the transport
parameters that the peer advertised during the handshake are authenticated; parameters that the peer advertised during the handshake are authenticated;
see <xref target="quic_parameters" format="default"/>.</t> see <xref target="quic_parameters" format="default"/>.</t>
<t>Once the handshake is complete, TLS becomes passive. TLS can still receive data <t>Once the handshake is complete, TLS becomes passive. TLS can still receive data
from its peer and respond in kind, but it will not need to send more data unless from its peer and respond in kind, but it will not need to send more data unless
specifically requested - either by an application or QUIC. One reason to send specifically requested -- either by an application or QUIC. One reason to send
data is that the server might wish to provide additional or updated session data is that the server might wish to provide additional or updated session
tickets to a client.</t> tickets to a client.</t>
<t>When the handshake is complete, QUIC only needs to provide TLS with any data <t>When the handshake is complete, QUIC only needs to provide TLS with any data
that arrives in CRYPTO streams. In the same manner that is used during the that arrives in CRYPTO streams. In the same manner that is used during the
handshake, new data is requested from TLS after providing received data.</t> handshake, new data is requested from TLS after providing received data.</t>
</section> </section>
<section anchor="encryption-level-changes" numbered="true" toc="default" > <section anchor="encryption-level-changes" numbered="true" toc="default" >
<name>Encryption Level Changes</name> <name>Encryption Level Changes</name>
<t>As keys at a given encryption level become available to TLS, TLS in dicates to <t>As keys at a given encryption level become available to TLS, TLS in dicates to
QUIC that reading or writing keys at that encryption level are available.</t> QUIC that reading or writing keys at that encryption level are available.</t>
<t>The availability of new keys is always a result of providing inputs to TLS. TLS <t>The availability of new keys is always a result of providing inputs to TLS. TLS
only provides new keys after being initialized (by a client) or when provided only provides new keys after being initialized (by a client) or when provided
with new handshake data.</t> with new handshake data.</t>
<t>However, a TLS implementation could perform some of its processing <t>However, a TLS implementation could perform some of its processing
asynchronously. In particular, the process of validating a certificate can take asynchronously. In particular, the process of validating a certificate can take
some time. While waiting for TLS processing to complete, an endpoint SHOULD some time. While waiting for TLS processing to complete, an endpoint <bcp14>SHOU
buffer received packets if they might be processed using keys that aren't yet LD</bcp14>
buffer received packets if they might be processed using keys that are not yet
available. These packets can be processed once keys are provided by TLS. An available. These packets can be processed once keys are provided by TLS. An
endpoint SHOULD continue to respond to packets that can be processed during this endpoint <bcp14>SHOULD</bcp14> continue to respond to packets that can be proces sed during this
time.</t> time.</t>
<t>After processing inputs, TLS might produce handshake bytes, keys fo r new <t>After processing inputs, TLS might produce handshake bytes, keys fo r new
encryption levels, or both.</t> encryption levels, or both.</t>
<t>TLS provides QUIC with three items as a new encryption level become s available:</t> <t>TLS provides QUIC with three items as a new encryption level become s available:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>A secret</li> <li>A secret</li>
<li>An Authenticated Encryption with Associated Data (AEAD) function </li> <li>An Authenticated Encryption with Associated Data (AEAD) function </li>
<li>A Key Derivation Function (KDF)</li> <li>A Key Derivation Function (KDF)</li>
</ul> </ul>
<t>These values are based on the values that TLS negotiates and are us ed by QUIC to <t>These values are based on the values that TLS negotiates and are us ed by QUIC to
skipping to change at line 438 skipping to change at line 423
one level. For instance, after sending its Finished message (using a CRYPTO one level. For instance, after sending its Finished message (using a CRYPTO
frame at the Handshake encryption level) an endpoint can send STREAM data (in frame at the Handshake encryption level) an endpoint can send STREAM data (in
1-RTT encryption). If the Finished message is lost, the endpoint uses the 1-RTT encryption). If the Finished message is lost, the endpoint uses the
Handshake encryption level to retransmit the lost message. Reordering or loss Handshake encryption level to retransmit the lost message. Reordering or loss
of packets can mean that QUIC will need to handle packets at multiple encryption of packets can mean that QUIC will need to handle packets at multiple encryption
levels. During the handshake, this means potentially handling packets at higher levels. During the handshake, this means potentially handling packets at higher
and lower encryption levels than the current encryption level used by TLS.</t> and lower encryption levels than the current encryption level used by TLS.</t>
<t>In particular, server implementations need to be able to read packe ts at the <t>In particular, server implementations need to be able to read packe ts at the
Handshake encryption level at the same time as the 0-RTT encryption level. A Handshake encryption level at the same time as the 0-RTT encryption level. A
client could interleave ACK frames that are protected with Handshake keys with client could interleave ACK frames that are protected with Handshake keys with
0-RTT data and the server needs to process those acknowledgments in order to 0-RTT data, and the server needs to process those acknowledgments in order to
detect lost Handshake packets.</t> detect lost Handshake packets.</t>
<t>QUIC also needs access to keys that might not ordinarily be availab le to a TLS <t>QUIC also needs access to keys that might not ordinarily be availab le to a TLS
implementation. For instance, a client might need to acknowledge Handshake implementation. For instance, a client might need to acknowledge Handshake
packets before it is ready to send CRYPTO frames at that encryption level. TLS packets before it is ready to send CRYPTO frames at that encryption level. TLS
therefore needs to provide keys to QUIC before it might produce them for its own therefore needs to provide keys to QUIC before it might produce them for its own
use.</t> use.</t>
</section> </section>
<section anchor="tls-interface-summary" numbered="true" toc="default"> <section anchor="tls-interface-summary" numbered="true" toc="default">
<name>TLS Interface Summary</name> <name>TLS Interface Summary</name>
<t><xref target="exchange-summary" format="default"/> summarizes the e xchange between QUIC and TLS for both <t><xref target="exchange-summary" format="default"/> summarizes the e xchange between QUIC and TLS for both
skipping to change at line 460 skipping to change at line 445
dashed arrows show where application data can be sent. Each arrow is tagged dashed arrows show where application data can be sent. Each arrow is tagged
with the encryption level used for that transmission.</t> with the encryption level used for that transmission.</t>
<figure anchor="exchange-summary"> <figure anchor="exchange-summary">
<name>Interaction Summary between QUIC and TLS</name> <name>Interaction Summary between QUIC and TLS</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
Client Server Client Server
====== ====== ====== ======
Get Handshake Get Handshake
Initial -------------> Initial ------------->
Install tx 0-RTT Keys Install tx 0-RTT keys
0-RTT - - - - - - - -> 0-RTT - - - - - - - ->
Handshake Received Handshake Received
Get Handshake Get Handshake
<------------- Initial <------------- Initial
Install rx 0-RTT keys Install rx 0-RTT keys
Install Handshake keys Install Handshake keys
Get Handshake Get Handshake
<----------- Handshake <----------- Handshake
Install tx 1-RTT keys Install tx 1-RTT keys
skipping to change at line 506 skipping to change at line 491
<t><xref target="exchange-summary" format="default"/> shows one possib le structure for a simple handshake <t><xref target="exchange-summary" format="default"/> shows one possib le structure for a simple handshake
exchange. The exact process varies based on the structure of endpoint exchange. The exact process varies based on the structure of endpoint
implementations and the order in which packets arrive. Implementations could implementations and the order in which packets arrive. Implementations could
use a different number of operations or execute them in other orders.</t> use a different number of operations or execute them in other orders.</t>
</section> </section>
</section> </section>
<section anchor="tls-version" numbered="true" toc="default"> <section anchor="tls-version" numbered="true" toc="default">
<name>TLS Version</name> <name>TLS Version</name>
<t>This document describes how TLS 1.3 <xref target="TLS13" format="defa ult"/> is used with QUIC.</t> <t>This document describes how TLS 1.3 <xref target="TLS13" format="defa ult"/> is used with QUIC.</t>
<t>In practice, the TLS handshake will negotiate a version of TLS to use . This <t>In practice, the TLS handshake will negotiate a version of TLS to use . This
could result in a newer version of TLS than 1.3 being negotiated if both could result in a version of TLS newer than 1.3 being negotiated if both
endpoints support that version. This is acceptable provided that the features endpoints support that version. This is acceptable provided that the features
of TLS 1.3 that are used by QUIC are supported by the newer version.</t> of TLS 1.3 that are used by QUIC are supported by the newer version.</t>
<t>Clients MUST NOT offer TLS versions older than 1.3. A badly configur ed TLS <t>Clients <bcp14>MUST NOT</bcp14> offer TLS versions older than 1.3. A badly configured TLS
implementation could negotiate TLS 1.2 or another older version of TLS. An implementation could negotiate TLS 1.2 or another older version of TLS. An
endpoint MUST terminate the connection if a version of TLS older than 1.3 is endpoint <bcp14>MUST</bcp14> terminate the connection if a version of TLS older than 1.3 is
negotiated.</t> negotiated.</t>
</section> </section>
<section anchor="clienthello-size" numbered="true" toc="default"> <section anchor="clienthello-size" numbered="true" toc="default">
<name>ClientHello Size</name> <name>ClientHello Size</name>
<t>The first Initial packet from a client contains the start or all of i ts first <t>The first Initial packet from a client contains the start or all of i ts first
cryptographic handshake message, which for TLS is the ClientHello. Servers cryptographic handshake message, which for TLS is the ClientHello. Servers
might need to parse the entire ClientHello (e.g., to access extensions such as might need to parse the entire ClientHello (e.g., to access extensions such as
Server Name Identification (SNI) or Application Layer Protocol Negotiation Server Name Identification (SNI) or Application-Layer Protocol Negotiation
(ALPN)) in order to decide whether to accept the new incoming QUIC connection. (ALPN)) in order to decide whether to accept the new incoming QUIC connection.
If the ClientHello spans multiple Initial packets, such servers would need to If the ClientHello spans multiple Initial packets, such servers would need to
buffer the first received fragments, which could consume excessive resources if buffer the first received fragments, which could consume excessive resources if
the client's address has not yet been validated. To avoid this, servers MAY the client's address has not yet been validated. To avoid this, servers <bcp14>
use the Retry feature (see Section 8.1 of <xref target="QUIC-TRANSPORT" format=" MAY</bcp14>
default"/>) to only buffer use the Retry feature (see <xref section="8.1" sectionFormat="of" target="QUIC-T
RANSPORT" format="default"/>) to only buffer
partial ClientHello messages from clients with a validated address.</t> partial ClientHello messages from clients with a validated address.</t>
<t>QUIC packet and framing add at least 36 bytes of overhead to the Clie ntHello <t>QUIC packet and framing add at least 36 bytes of overhead to the Clie ntHello
message. That overhead increases if the client chooses a source connection ID message. That overhead increases if the client chooses a Source Connection ID
longer than zero bytes. Overheads also do not include the token or a field longer than zero bytes. Overheads also do not include the token or a
destination connection ID longer than 8 bytes, both of which might be required Destination Connection ID longer than 8 bytes, both of which might be required
if a server sends a Retry packet.</t> if a server sends a Retry packet.</t>
<t>A typical TLS ClientHello can easily fit into a 1200-byte packet. Ho wever, in <t>A typical TLS ClientHello can easily fit into a 1200-byte packet. Ho wever, in
addition to the overheads added by QUIC, there are several variables that could addition to the overheads added by QUIC, there are several variables that could
cause this limit to be exceeded. Large session tickets, multiple or large key cause this limit to be exceeded. Large session tickets, multiple or large key
shares, and long lists of supported ciphers, signature algorithms, versions, shares, and long lists of supported ciphers, signature algorithms, versions,
QUIC transport parameters, and other negotiable parameters and extensions could QUIC transport parameters, and other negotiable parameters and extensions could
cause this message to grow.</t> cause this message to grow.</t>
<t>For servers, in addition to connection IDs and tokens, the size of TL S session <t>For servers, in addition to connection IDs and tokens, the size of TL S session
tickets can have an effect on a client's ability to connect efficiently. tickets can have an effect on a client's ability to connect efficiently.
Minimizing the size of these values increases the probability that clients can Minimizing the size of these values increases the probability that clients can
use them and still fit their entire ClientHello message in their first Initial use them and still fit their entire ClientHello message in their first Initial
packet.</t> packet.</t>
<t>The TLS implementation does not need to ensure that the ClientHello i s large <t>The TLS implementation does not need to ensure that the ClientHello i s large
enough to meet the requirements for QUIC packets. QUIC PADDING frames are added enough to meet QUIC's requirements for datagrams that carry Initial packets; see
to increase the size of the packet as necessary; see Section 14.1 of <xref section="14.1" sectionFormat="of" target="QUIC-TRANSPORT" format="default"
<xref target="QUIC-TRANSPORT" format="default"/>.</t> />. QUIC implementations use PADDING frames or
packet coalescing to ensure that datagrams are large enough.</t>
</section> </section>
<section anchor="peer-authentication" numbered="true" toc="default"> <section anchor="peer-authentication" numbered="true" toc="default">
<name>Peer Authentication</name> <name>Peer Authentication</name>
<t>The requirements for authentication depend on the application protoco l that is <t>The requirements for authentication depend on the application protoco l that is
in use. TLS provides server authentication and permits the server to request in use. TLS provides server authentication and permits the server to request
client authentication.</t> client authentication.</t>
<t>A client MUST authenticate the identity of the server. This typicall y involves <t>A client <bcp14>MUST</bcp14> authenticate the identity of the server. This typically involves
verification that the identity of the server is included in a certificate and verification that the identity of the server is included in a certificate and
that the certificate is issued by a trusted entity (see for example that the certificate is issued by a trusted entity (see for example
<xref target="RFC2818" format="default"/>).</t> <xref target="RFC2818" format="default"/>).</t>
<dl> <aside>
<dt> <t>Note: Where servers provide certificates for authentication, the si
Note: </dt> ze of the
<dd> certificate chain can consume a large number of bytes. Controlling the size
<t>Where servers provide certificates for authentication, the size o of certificate chains is critical to performance in QUIC as servers are
f limited to sending 3 bytes for every byte received prior to validating the
the certificate chain can consume a large number of bytes. Controlling the client address; see <xref section="8.1" sectionFormat="of" target="QUIC-TRANSP
size of certificate chains is critical to performance in QUIC as servers are ORT" format="default"/>. The size of a
limited to sending 3 bytes for every byte received prior to validating the certificate chain can be managed by limiting the number of names or
client address; see Section 8.1 of <xref target="QUIC-TRANSPORT" format="default extensions; using keys with small public key representations, like ECDSA; or
"/>. The size of a by using certificate compression <xref target="COMPRESS" format="default"/>.</
certificate chain can be managed by limiting the number of names or t>
extensions; using keys with small public key representations, like ECDSA; or </aside>
by using certificate compression <t>A server <bcp14>MAY</bcp14> request that the client authenticate duri
<xref target="COMPRESS" format="default"/>.</t> ng the handshake. A server
</dd> <bcp14>MAY</bcp14> refuse a connection if the client is unable to authenticate w
</dl> hen requested.
<t>A server MAY request that the client authenticate during the handshak
e. A server
MAY refuse a connection if the client is unable to authenticate when requested.
The requirements for client authentication vary based on application protocol The requirements for client authentication vary based on application protocol
and deployment.</t> and deployment.</t>
<t>A server MUST NOT use post-handshake client authentication (as define <t>A server <bcp14>MUST NOT</bcp14> use post-handshake client authentica
d in tion (as defined in
Section 4.6.2 of <xref target="TLS13" format="default"/>), because the multiplex <xref section="4.6.2" sectionFormat="of" target="TLS13" format="default"/>) beca
ing offered by QUIC prevents use the multiplexing offered by QUIC prevents
clients from correlating the certificate request with the application-level clients from correlating the certificate request with the application-level
event that triggered it (see <xref target="HTTP2-TLS13" format="default"/>). event that triggered it (see <xref target="HTTP2-TLS13" format="default"/>). Mo
More specifically, servers MUST NOT send post-handshake TLS CertificateRequest re specifically,
messages and clients MUST treat receipt of such messages as a connection error servers <bcp14>MUST NOT</bcp14> send post-handshake TLS CertificateRequest messa
of type PROTOCOL_VIOLATION.</t> ges, and
clients <bcp14>MUST</bcp14> treat receipt of such messages as a connection error
of type
PROTOCOL_VIOLATION.</t>
</section> </section>
<section anchor="resumption" numbered="true" toc="default"> <section anchor="resumption" numbered="true" toc="default">
<name>Session Resumption</name> <name>Session Resumption</name>
<t>QUIC can use the session resumption feature of TLS 1.3. It does this by <t>QUIC can use the session resumption feature of TLS 1.3. It does this by
carrying NewSessionTicket messages in CRYPTO frames after the handshake is carrying NewSessionTicket messages in CRYPTO frames after the handshake is
complete. Session resumption can be used to provide 0-RTT, and can also be complete. Session resumption can be used to provide 0-RTT and can also be
used when 0-RTT is disabled.</t> used when 0-RTT is disabled.</t>
<t>Endpoints that use session resumption might need to remember some inf ormation <t>Endpoints that use session resumption might need to remember some inf ormation
about the current connection when creating a resumed connection. TLS requires about the current connection when creating a resumed connection. TLS requires
that some information be retained; see Section 4.6.1 of <xref target="TLS13" for that some information be retained; see <xref section="4.6.1" sectionFormat="of"
mat="default"/>. QUIC itself target="TLS13" format="default"/>. QUIC itself
does not depend on any state being retained when resuming a connection, unless does not depend on any state being retained when resuming a connection unless
0-RTT is also used; see Section 7.4.1 of <xref target="QUIC-TRANSPORT" format="d 0-RTT is also used; see <xref section="7.4.1" sectionFormat="of" target="QUIC-TR
efault"/> and ANSPORT" format="default"/> and
<xref target="enable-0rtt" format="default"/>. Application protocols could depen d on state that is retained <xref target="enable-0rtt" format="default"/>. Application protocols could depen d on state that is retained
between resumed connections.</t> between resumed connections.</t>
<t>Clients can store any state required for resumption along with the se ssion <t>Clients can store any state required for resumption along with the se ssion
ticket. Servers can use the session ticket to help carry state.</t> ticket. Servers can use the session ticket to help carry state.</t>
<t>Session resumption allows servers to link activity on the original co nnection <t>Session resumption allows servers to link activity on the original co nnection
with the resumed connection, which might be a privacy issue for clients. with the resumed connection, which might be a privacy issue for clients.
Clients can choose not to enable resumption to avoid creating this correlation. Clients can choose not to enable resumption to avoid creating this correlation.
Clients SHOULD NOT reuse tickets as that allows entities other than the server Clients <bcp14>SHOULD NOT</bcp14> reuse tickets as that allows entities other th
to correlate connections; see Section C.4 of <xref target="TLS13" format="defaul an the server
t"/>.</t> to correlate connections; see <xref section="C.4" sectionFormat="of" target="TLS
13" format="default"/>.</t>
</section> </section>
<section anchor="rtt" numbered="true" toc="default"> <section anchor="rtt" numbered="true" toc="default">
<name>0-RTT</name> <name>0-RTT</name>
<t>The 0-RTT feature in QUIC allows a client to send application data be fore the <t>The 0-RTT feature in QUIC allows a client to send application data be fore the
handshake is complete. This is made possible by reusing negotiated parameters handshake is complete. This is made possible by reusing negotiated parameters
from a previous connection. To enable this, 0-RTT depends on the client from a previous connection. To enable this, 0-RTT depends on the client
remembering critical parameters and providing the server with a TLS session remembering critical parameters and providing the server with a TLS session
ticket that allows the server to recover the same information.</t> ticket that allows the server to recover the same information.</t>
<t>This information includes parameters that determine TLS state, as gov erned by <t>This information includes parameters that determine TLS state, as gov erned by
<xref target="TLS13" format="default"/>, QUIC transport parameters, the chosen a pplication protocol, and any <xref target="TLS13" format="default"/>, QUIC transport parameters, the chosen a pplication protocol, and any
information the application protocol might need; see <xref target="app-0rtt" for mat="default"/>. This information the application protocol might need; see <xref target="app-0rtt" for mat="default"/>. This
information determines how 0-RTT packets and their contents are formed.</t> information determines how 0-RTT packets and their contents are formed.</t>
<t>To ensure that the same information is available to both endpoints, a ll <t>To ensure that the same information is available to both endpoints, a ll
information used to establish 0-RTT comes from the same connection. Endpoints information used to establish 0-RTT comes from the same connection. Endpoints
cannot selectively disregard information that might alter the sending or cannot selectively disregard information that might alter the sending or
processing of 0-RTT.</t> processing of 0-RTT.</t>
<t><xref target="TLS13" format="default"/> sets a limit of 7 days on the <t><xref target="TLS13" format="default"/> sets a limit of seven days on
time between the original connection the time between the original
and any attempt to use 0-RTT. There are other constraints on 0-RTT usage, connection and any attempt to use 0-RTT. There are other constraints on 0-RTT
notably those caused by the potential exposure to replay attack; see <xref targe usage, notably those caused by the potential exposure to replay attack; see
t="replay" format="default"/>.</t> <xref target="replay" format="default"/>.</t>
<section anchor="enable-0rtt" numbered="true" toc="default"> <section anchor="enable-0rtt" numbered="true" toc="default">
<name>Enabling 0-RTT</name> <name>Enabling 0-RTT</name>
<t>The TLS "early_data" extension in the NewSessionTicket message is d <t>The TLS early_data extension in the NewSessionTicket message is def
efined ined to
to convey (in the "max_early_data_size" parameter) the amount of TLS 0-RTT convey (in the max_early_data_size parameter) the amount of TLS 0-RTT data the
data the server is willing to accept. QUIC does not use TLS 0-RTT data. server is willing to accept. QUIC does not use TLS early data. QUIC uses 0-RTT
QUIC uses 0-RTT packets to carry early data. Accordingly, the packets to carry early data. Accordingly, the max_early_data_size parameter is
"max_early_data_size" parameter is repurposed to hold a sentinel value repurposed to hold a sentinel value 0xffffffff to indicate that the server is
0xffffffff to indicate that the server is willing to accept QUIC 0-RTT data; willing to accept QUIC 0-RTT data. To indicate that the server does not accept
to indicate that the server does not accept 0-RTT data, the "early_data" 0-RTT data, the early_data extension is omitted from the NewSessionTicket. The
extension is omitted from the NewSessionTicket. amount of data that the client can send in QUIC 0-RTT is controlled by the
The amount of data that the client can send in QUIC 0-RTT is initial_max_data transport parameter supplied by the server.</t>
controlled by the initial_max_data transport parameter supplied by the server.</ <t>Servers <bcp14>MUST NOT</bcp14> send the early_data extension with
t> a max_early_data_size field
<t>Servers MUST NOT send the early_data extension with a max_early_dat set to any value other than 0xffffffff. A client <bcp14>MUST</bcp14> treat rece
a_size field ipt of a
set to any value other than 0xffffffff. A client MUST treat receipt of a
NewSessionTicket that contains an early_data extension with any other value as NewSessionTicket that contains an early_data extension with any other value as
a connection error of type PROTOCOL_VIOLATION.</t> a connection error of type PROTOCOL_VIOLATION.</t>
<t>A client that wishes to send 0-RTT packets uses the early_data exte <t>A client that wishes to send 0-RTT packets uses the early_data exte
nsion in nsion in the
the ClientHello message of a subsequent handshake; see Section 4.2.10 of ClientHello message of a subsequent handshake; see <xref section="4.2.10" sectio
<xref target="TLS13" format="default"/>. It then sends application data in 0-RTT nFormat="of" target="TLS13" format="default"/>.
packets.</t> It then sends application data in 0-RTT packets.</t>
<t>A client that attempts 0-RTT might also provide an address validati on token if <t>A client that attempts 0-RTT might also provide an address validati on token if
the server has sent a NEW_TOKEN frame; see Section 8.1 of <xref target="QUIC-TRA NSPORT" format="default"/>.</t> the server has sent a NEW_TOKEN frame; see <xref section="8.1" sectionFormat="of " target="QUIC-TRANSPORT" format="default"/>.</t>
</section> </section>
<section anchor="accepting-and-rejecting-0-rtt" numbered="true" toc="def ault"> <section anchor="accepting-and-rejecting-0-rtt" numbered="true" toc="def ault">
<name>Accepting and Rejecting 0-RTT</name> <name>Accepting and Rejecting 0-RTT</name>
<t>A server accepts 0-RTT by sending an early_data extension in the <t>A server accepts 0-RTT by sending an early_data extension in the
EncryptedExtensions; see Section 4.2.10 of <xref target="TLS13" format="default" />. The server then EncryptedExtensions; see <xref section="4.2.10" sectionFormat="of" target="TLS13 " format="default"/>. The server then
processes and acknowledges the 0-RTT packets that it receives.</t> processes and acknowledges the 0-RTT packets that it receives.</t>
<t>A server rejects 0-RTT by sending the EncryptedExtensions without a n early_data <t>A server rejects 0-RTT by sending the EncryptedExtensions without a n early_data
extension. A server will always reject 0-RTT if it sends a TLS extension. A server will always reject 0-RTT if it sends a TLS
HelloRetryRequest. When rejecting 0-RTT, a server MUST NOT process any 0-RTT HelloRetryRequest. When rejecting 0-RTT, a server <bcp14>MUST NOT</bcp14> proce
packets, even if it could. When 0-RTT was rejected, a client SHOULD treat ss any 0-RTT
packets, even if it could. When 0-RTT was rejected, a client <bcp14>SHOULD</bcp
14> treat
receipt of an acknowledgment for a 0-RTT packet as a connection error of type receipt of an acknowledgment for a 0-RTT packet as a connection error of type
PROTOCOL_VIOLATION, if it is able to detect the condition.</t> PROTOCOL_VIOLATION, if it is able to detect the condition.</t>
<t>When 0-RTT is rejected, all connection characteristics that the cli ent assumed <t>When 0-RTT is rejected, all connection characteristics that the cli ent assumed
might be incorrect. This includes the choice of application protocol, transport might be incorrect. This includes the choice of application protocol, transport
parameters, and any application configuration. The client therefore MUST reset parameters, and any application configuration. The client therefore <bcp14>MUST </bcp14> reset
the state of all streams, including application state bound to those streams.</t > the state of all streams, including application state bound to those streams.</t >
<t>A client MAY reattempt 0-RTT if it receives a Retry or Version Nego tiation <t>A client <bcp14>MAY</bcp14> reattempt 0-RTT if it receives a Retry or Version Negotiation
packet. These packets do not signify rejection of 0-RTT.</t> packet. These packets do not signify rejection of 0-RTT.</t>
</section> </section>
<section anchor="app-0rtt" numbered="true" toc="default"> <section anchor="app-0rtt" numbered="true" toc="default">
<name>Validating 0-RTT Configuration</name> <name>Validating 0-RTT Configuration</name>
<t>When a server receives a ClientHello with the early_data extension, it has to <t>When a server receives a ClientHello with the early_data extension, it has to
decide whether to accept or reject early data from the client. Some of this decide whether to accept or reject 0-RTT data from the client. Some of this
decision is made by the TLS stack (e.g., checking that the cipher suite being decision is made by the TLS stack (e.g., checking that the cipher suite being
resumed was included in the ClientHello; see Section 4.2.10 of <xref target="TLS resumed was included in the ClientHello; see <xref section="4.2.10" sectionForma
13" format="default"/>). Even t="of" target="TLS13" format="default"/>). Even
when the TLS stack has no reason to reject early data, the QUIC stack or the when the TLS stack has no reason to reject 0-RTT data, the QUIC stack or the
application protocol using QUIC might reject early data because the application protocol using QUIC might reject 0-RTT data because the
configuration of the transport or application associated with the resumed configuration of the transport or application associated with the resumed
session is not compatible with the server's current configuration.</t> session is not compatible with the server's current configuration.</t>
<t>QUIC requires additional transport state to be associated with a 0- RTT session <t>QUIC requires additional transport state to be associated with a 0- RTT session
ticket. One common way to implement this is using stateless session tickets and ticket. One common way to implement this is using stateless session tickets and
storing this state in the session ticket. Application protocols that use QUIC storing this state in the session ticket. Application protocols that use QUIC
might have similar requirements regarding associating or storing state. This might have similar requirements regarding associating or storing state. This
associated state is used for deciding whether early data must be rejected. For associated state is used for deciding whether 0-RTT data must be rejected. For
example, HTTP/3 (<xref target="QUIC-HTTP" format="default"/>) settings determine example, HTTP/3 settings <xref target="QUIC-HTTP" format="default"/> determine h
how early data from the ow 0-RTT data from the
client is interpreted. Other applications using QUIC could have different client is interpreted. Other applications using QUIC could have different
requirements for determining whether to accept or reject early data.</t> requirements for determining whether to accept or reject 0-RTT data.</t>
</section> </section>
</section> </section>
<section anchor="helloretryrequest" numbered="true" toc="default"> <section anchor="helloretryrequest" numbered="true" toc="default">
<name>HelloRetryRequest</name> <name>HelloRetryRequest</name>
<t>The HelloRetryRequest message (see Section 4.1.4 of <xref target="TLS 13" format="default"/>) can be used to <t>The HelloRetryRequest message (see <xref section="4.1.4" sectionForma t="of" target="TLS13" format="default"/>) can be used to
request that a client provide new information, such as a key share, or to request that a client provide new information, such as a key share, or to
validate some characteristic of the client. From the perspective of QUIC, validate some characteristic of the client. From the perspective of QUIC,
HelloRetryRequest is not differentiated from other cryptographic handshake HelloRetryRequest is not differentiated from other cryptographic handshake
messages that are carried in Initial packets. Although it is in principle messages that are carried in Initial packets. Although it is in principle
possible to use this feature for address verification, QUIC implementations possible to use this feature for address verification, QUIC implementations
SHOULD instead use the Retry feature; see Section 8.1 of <xref target="QUIC-TRAN SPORT" format="default"/>.</t> <bcp14>SHOULD</bcp14> instead use the Retry feature; see <xref section="8.1" sec tionFormat="of" target="QUIC-TRANSPORT" format="default"/>.</t>
</section> </section>
<section anchor="tls-errors" numbered="true" toc="default"> <section anchor="tls-errors" numbered="true" toc="default">
<name>TLS Errors</name> <name>TLS Errors</name>
<t>If TLS experiences an error, it generates an appropriate alert as def ined in <t>If TLS experiences an error, it generates an appropriate alert as def ined in
Section 6 of <xref target="TLS13" format="default"/>.</t> <xref section="6" sectionFormat="of" target="TLS13" format="default"/>.</t>
<t>A TLS alert is converted into a QUIC connection error. The AlertDescr iption <t>A TLS alert is converted into a QUIC connection error. The AlertDescr iption
value is value is
added to 0x100 to produce a QUIC error code from the range reserved for added to 0x0100 to produce a QUIC error code from the range reserved for
CRYPTO_ERROR. The resulting value is sent in a QUIC CONNECTION_CLOSE frame of CRYPTO_ERROR; see <xref section="20.1" sectionFormat="of" target="QUIC-TRANSPORT
type 0x1c.</t> " format="default"/>. The resulting value is
sent in a QUIC CONNECTION_CLOSE frame of type 0x1c.</t>
<t>QUIC is only able to convey an alert level of "fatal". In TLS 1.3, th e only <t>QUIC is only able to convey an alert level of "fatal". In TLS 1.3, th e only
existing uses for the "warning" level are to signal connection close; see existing uses for the "warning" level are to signal connection close; see
Section 6.1 of <xref target="TLS13" format="default"/>. As QUIC provides alterna tive mechanisms for <xref section="6.1" sectionFormat="of" target="TLS13" format="default"/>. As QUI C provides alternative mechanisms for
connection termination and the TLS connection is only closed if an error is connection termination and the TLS connection is only closed if an error is
encountered, a QUIC endpoint MUST treat any alert from TLS as if it were at the encountered, a QUIC endpoint <bcp14>MUST</bcp14> treat any alert from TLS as if it were at the
"fatal" level.</t> "fatal" level.</t>
<t>QUIC permits the use of a generic code in place of a specific error c ode; see <t>QUIC permits the use of a generic code in place of a specific error c ode; see
Section 11 of <xref target="QUIC-TRANSPORT" format="default"/>. For TLS alerts, <xref section="11" sectionFormat="of" target="QUIC-TRANSPORT" format="default"/>
this includes replacing any . For TLS alerts, this includes replacing any
alert with a generic alert, such as handshake_failure (0x128 in QUIC). alert with a generic alert, such as handshake_failure (0x0128 in QUIC).
Endpoints MAY use a generic error code to avoid possibly exposing confidential Endpoints <bcp14>MAY</bcp14> use a generic error code to avoid possibly exposing
confidential
information.</t> information.</t>
</section> </section>
<section anchor="discarding-unused-keys" numbered="true" toc="default"> <section anchor="discarding-unused-keys" numbered="true" toc="default">
<name>Discarding Unused Keys</name> <name>Discarding Unused Keys</name>
<t>After QUIC has completed a move to a new encryption level, packet pro tection <t>After QUIC has completed a move to a new encryption level, packet pro tection
keys for previous encryption levels can be discarded. This occurs several times keys for previous encryption levels can be discarded. This occurs several times
during the handshake, as well as when keys are updated; see <xref target="key-up date" format="default"/>.</t> during the handshake, as well as when keys are updated; see <xref target="key-up date" format="default"/>.</t>
<t>Packet protection keys are not discarded immediately when new keys ar e <t>Packet protection keys are not discarded immediately when new keys ar e
available. If packets from a lower encryption level contain CRYPTO frames, available. If packets from a lower encryption level contain CRYPTO frames,
frames that retransmit that data MUST be sent at the same encryption level. frames that retransmit that data <bcp14>MUST</bcp14> be sent at the same encrypt ion level.
Similarly, an endpoint generates acknowledgments for packets at the same Similarly, an endpoint generates acknowledgments for packets at the same
encryption level as the packet being acknowledged. Thus, it is possible that encryption level as the packet being acknowledged. Thus, it is possible that
keys for a lower encryption level are needed for a short time after keys for a keys for a lower encryption level are needed for a short time after keys for a
newer encryption level are available.</t> newer encryption level are available.</t>
<t>An endpoint cannot discard keys for a given encryption level unless i t has <t>An endpoint cannot discard keys for a given encryption level unless i t has
received all the cryptographic handshake messages from its peer at that received all the cryptographic handshake messages from its peer at that
encryption level and its peer has done the same. Different methods for encryption level and its peer has done the same. Different methods for
determining this are provided for Initial keys (<xref target="discard-initial" f ormat="default"/>) and determining this are provided for Initial keys (<xref target="discard-initial" f ormat="default"/>) and
Handshake keys (<xref target="discard-handshake" format="default"/>). These met hods do not prevent packets Handshake keys (<xref target="discard-handshake" format="default"/>). These met hods do not prevent packets
from being received or sent at that encryption level because a peer might not from being received or sent at that encryption level because a peer might not
have received all the acknowledgments necessary.</t> have received all the acknowledgments necessary.</t>
<t>Though an endpoint might retain older keys, new data MUST be sent at <t>Though an endpoint might retain older keys, new data <bcp14>MUST</bcp
the highest 14> be sent at the highest
currently-available encryption level. Only ACK frames and retransmissions of currently available encryption level. Only ACK frames and retransmissions of
data in CRYPTO frames are sent at a previous encryption level. These packets data in CRYPTO frames are sent at a previous encryption level. These packets
MAY also include PADDING frames.</t> <bcp14>MAY</bcp14> also include PADDING frames.</t>
<section anchor="discard-initial" numbered="true" toc="default"> <section anchor="discard-initial" numbered="true" toc="default">
<name>Discarding Initial Keys</name> <name>Discarding Initial Keys</name>
<t>Packets protected with Initial secrets (<xref target="initial-secre ts" format="default"/>) are not <t>Packets protected with Initial secrets (<xref target="initial-secre ts" format="default"/>) are not
authenticated, meaning that an attacker could spoof packets with the intent to authenticated, meaning that an attacker could spoof packets with the intent to
disrupt a connection. To limit these attacks, Initial packet protection keys disrupt a connection. To limit these attacks, Initial packet protection keys
are discarded more aggressively than other keys.</t> are discarded more aggressively than other keys.</t>
<t>The successful use of Handshake packets indicates that no more Init ial packets <t>The successful use of Handshake packets indicates that no more Init ial packets
need to be exchanged, as these keys can only be produced after receiving all need to be exchanged, as these keys can only be produced after receiving all
CRYPTO frames from Initial packets. Thus, a client MUST discard Initial keys CRYPTO frames from Initial packets. Thus, a client <bcp14>MUST</bcp14> discard
when it first sends a Handshake packet and a server MUST discard Initial keys Initial keys
when it first successfully processes a Handshake packet. Endpoints MUST NOT when it first sends a Handshake packet and a server <bcp14>MUST</bcp14> discard
Initial keys
when it first successfully processes a Handshake packet. Endpoints <bcp14>MUST
NOT</bcp14>
send Initial packets after this point.</t> send Initial packets after this point.</t>
<t>This results in abandoning loss recovery state for the Initial encr yption level <t>This results in abandoning loss recovery state for the Initial encr yption level
and ignoring any outstanding Initial packets.</t> and ignoring any outstanding Initial packets.</t>
</section> </section>
<section anchor="discard-handshake" numbered="true" toc="default"> <section anchor="discard-handshake" numbered="true" toc="default">
<name>Discarding Handshake Keys</name> <name>Discarding Handshake Keys</name>
<t>An endpoint MUST discard its handshake keys when the TLS handshake is confirmed <t>An endpoint <bcp14>MUST</bcp14> discard its Handshake keys when the TLS handshake is confirmed
(<xref target="handshake-confirmed" format="default"/>).</t> (<xref target="handshake-confirmed" format="default"/>).</t>
</section> </section>
<section anchor="discarding-0-rtt-keys" numbered="true" toc="default"> <section anchor="discarding-0-rtt-keys" numbered="true" toc="default">
<name>Discarding 0-RTT Keys</name> <name>Discarding 0-RTT Keys</name>
<t>0-RTT and 1-RTT packets share the same packet number space, and cli ents do not <t>0-RTT and 1-RTT packets share the same packet number space, and cli ents do not
send 0-RTT packets after sending a 1-RTT packet (<xref target="using-early-data" format="default"/>).</t> send 0-RTT packets after sending a 1-RTT packet (<xref target="using-early-data" format="default"/>).</t>
<t>Therefore, a client SHOULD discard 0-RTT keys as soon as it install <t>Therefore, a client <bcp14>SHOULD</bcp14> discard 0-RTT keys as soo
s 1-RTT n as it installs 1-RTT
keys, since they have no use after that moment.</t> keys as they have no use after that moment.</t>
<t>Additionally, a server MAY discard 0-RTT keys as soon as it receive <t>Additionally, a server <bcp14>MAY</bcp14> discard 0-RTT keys as soo
s a 1-RTT n as it receives a 1-RTT
packet. However, due to packet reordering, a 0-RTT packet could arrive after packet. However, due to packet reordering, a 0-RTT packet could arrive after
a 1-RTT packet. Servers MAY temporarily retain 0-RTT keys to allow decrypting a 1-RTT packet. Servers <bcp14>MAY</bcp14> temporarily retain 0-RTT keys to all ow decrypting
reordered packets without requiring their contents to be retransmitted with reordered packets without requiring their contents to be retransmitted with
1-RTT keys. After receiving a 1-RTT packet, servers MUST discard 0-RTT keys 1-RTT keys. After receiving a 1-RTT packet, servers <bcp14>MUST</bcp14> discard
within a short time; the RECOMMENDED time period is three times the Probe 0-RTT keys
Timeout (PTO, see <xref target="QUIC-RECOVERY" format="default"/>). A server MA within a short time; the <bcp14>RECOMMENDED</bcp14> time period is three times t
Y discard 0-RTT keys earlier he Probe
Timeout (PTO, see <xref target="QUIC-RECOVERY" format="default"/>). A server <b
cp14>MAY</bcp14> discard 0-RTT keys earlier
if it determines that it has received all 0-RTT packets, which can be done by if it determines that it has received all 0-RTT packets, which can be done by
keeping track of missing packet numbers.</t> keeping track of missing packet numbers.</t>
</section> </section>
</section> </section>
</section> </section>
<section anchor="packet-protection" numbered="true" toc="default"> <section anchor="packet-protection" numbered="true" toc="default">
<name>Packet Protection</name> <name>Packet Protection</name>
<t>As with TLS over TCP, QUIC protects packets with keys derived from the TLS <t>As with TLS over TCP, QUIC protects packets with keys derived from the TLS
handshake, using the AEAD algorithm <xref target="AEAD" format="default"/> negot iated by TLS.</t> handshake, using the AEAD algorithm <xref target="AEAD" format="default"/> negot iated by TLS.</t>
<t>QUIC packets have varying protections depending on their type:</t> <t>QUIC packets have varying protections depending on their type:</t>
skipping to change at line 801 skipping to change at line 781
0-RTT packets, and 1-RTT packets. The same packet protection process is applied 0-RTT packets, and 1-RTT packets. The same packet protection process is applied
to Initial packets. However, as it is trivial to determine the keys used for to Initial packets. However, as it is trivial to determine the keys used for
Initial packets, these packets are not considered to have confidentiality or Initial packets, these packets are not considered to have confidentiality or
integrity protection. Retry packets use a fixed key and so similarly lack integrity protection. Retry packets use a fixed key and so similarly lack
confidentiality and integrity protection.</t> confidentiality and integrity protection.</t>
<section anchor="protection-keys" numbered="true" toc="default"> <section anchor="protection-keys" numbered="true" toc="default">
<name>Packet Protection Keys</name> <name>Packet Protection Keys</name>
<t>QUIC derives packet protection keys in the same way that TLS derives record <t>QUIC derives packet protection keys in the same way that TLS derives record
protection keys.</t> protection keys.</t>
<t>Each encryption level has separate secret values for protection of pa ckets sent <t>Each encryption level has separate secret values for protection of pa ckets sent
in each direction. These traffic secrets are derived by TLS (see Section 7.1 of in each direction. These traffic secrets are derived by TLS (see <xref section="
<xref target="TLS13" format="default"/>) and are used by QUIC for all encryption 7.1" sectionFormat="of" target="TLS13" format="default"/>) and are used by QUIC
levels except the Initial for all encryption levels except the Initial
encryption level. The secrets for the Initial encryption level are computed encryption level. The secrets for the Initial encryption level are computed
based on the client's initial Destination Connection ID, as described in based on the client's initial Destination Connection ID, as described in
<xref target="initial-secrets" format="default"/>.</t> <xref target="initial-secrets" format="default"/>.</t>
<t>The keys used for packet protection are computed from the TLS secrets using the <t>The keys used for packet protection are computed from the TLS secrets using the
KDF provided by TLS. In TLS 1.3, the HKDF-Expand-Label function described in KDF provided by TLS. In TLS 1.3, the HKDF-Expand-Label function described in
Section 7.1 of <xref target="TLS13" format="default"/> is used, using the hash f unction from the negotiated <xref section="7.1" sectionFormat="of" target="TLS13" format="default"/> is used with the hash function from the negotiated
cipher suite. All uses of HKDF-Expand-Label in QUIC use a zero-length Context.< /t> cipher suite. All uses of HKDF-Expand-Label in QUIC use a zero-length Context.< /t>
<t>Note that labels, which are described using strings, are encoded <t>Note that labels, which are described using strings, are encoded
as bytes using ASCII <xref target="ASCII" format="default"/> without quotes or a ny trailing NUL as bytes using ASCII <xref target="ASCII" format="default"/> without quotes or a ny trailing NUL
byte.</t> byte.</t>
<t>Other versions of TLS MUST provide a similar function in order to be <t>Other versions of TLS <bcp14>MUST</bcp14> provide a similar function in order to be
used with QUIC.</t> used with QUIC.</t>
<t>The current encryption level secret and the label "quic key" are inpu t to the <t>The current encryption level secret and the label "quic key" are inpu t to the
KDF to produce the AEAD key; the label "quic iv" is used to derive the KDF to produce the AEAD key; the label "quic iv" is used to derive the
Initialization Vector (IV); see <xref target="aead" format="default"/>. The hea der protection key uses the Initialization Vector (IV); see <xref target="aead" format="default"/>. The hea der protection key uses the
"quic hp" label; see <xref target="header-protect" format="default"/>. Using th ese labels provides key "quic hp" label; see <xref target="header-protect" format="default"/>. Using th ese labels provides key
separation between QUIC and TLS; see <xref target="key-diversity" format="defaul t"/>.</t> separation between QUIC and TLS; see <xref target="key-diversity" format="defaul t"/>.</t>
<t>Both "quic key" and "quic hp" are used to produce keys, so the Length provided <t>Both "quic key" and "quic hp" are used to produce keys, so the Length provided
to HKDF-Expand-Label along with these labels is determined by the size of keys to HKDF-Expand-Label along with these labels is determined by the size of keys
in the AEAD or header protection algorithm. The Length provided with "quic iv" in the AEAD or header protection algorithm. The Length provided with "quic iv"
is the minimum length of the AEAD nonce, or 8 bytes if that is larger; see is the minimum length of the AEAD nonce or 8 bytes if that is larger; see
<xref target="AEAD" format="default"/>.</t> <xref target="AEAD" format="default"/>.</t>
<t>The KDF used for initial secrets is always the HKDF-Expand-Label func tion from <t>The KDF used for initial secrets is always the HKDF-Expand-Label func tion from
TLS 1.3; see <xref target="initial-secrets" format="default"/>.</t> TLS 1.3; see <xref target="initial-secrets" format="default"/>.</t>
</section> </section>
<section anchor="initial-secrets" numbered="true" toc="default"> <section anchor="initial-secrets" numbered="true" toc="default">
<name>Initial Secrets</name> <name>Initial Secrets</name>
<t>Initial packets apply the packet protection process, but use a secret derived <t>Initial packets apply the packet protection process, but use a secret derived
from the Destination Connection ID field from the client's first Initial from the Destination Connection ID field from the client's first Initial
packet.</t> packet.</t>
<t>This secret is determined by using HKDF-Extract (see Section 2.2 of <t>This secret is determined by using HKDF-Extract (see <xref section="2
<xref target="HKDF" format="default"/>) with a salt of 0x38762cf7f55934b34d179ae .2" sectionFormat="of" target="HKDF" format="default"/>)
6a4c80cadccbb7f0a with a salt of 0x38762cf7f55934b34d179ae6a4c80cadccbb7f0a and the input keying
and a IKM of the Destination Connection ID field. This produces an intermediate material (IKM) of the Destination Connection ID field. This produces an
pseudorandom key (PRK) that is used to derive two separate secrets for sending intermediate pseudorandom key (PRK) that is used to derive two separate secrets
and receiving.</t> for sending and receiving.</t>
<t>The secret used by clients to construct Initial packets uses the PRK and the <t>The secret used by clients to construct Initial packets uses the PRK and the
label "client in" as input to the HKDF-Expand-Label function from TLS label "client in" as input to the HKDF-Expand-Label function from TLS
<xref target="TLS13" format="default"/> to produce a 32-byte secret. Packets co nstructed by the server use <xref target="TLS13" format="default"/> to produce a 32-byte secret. Packets co nstructed by the server use
the same process with the label "server in". The hash function for HKDF when the same process with the label "server in". The hash function for HKDF when
deriving initial secrets and keys is SHA-256 deriving initial secrets and keys is SHA-256
<xref target="SHA" format="default"/>.</t> <xref target="SHA" format="default"/>.</t>
<t>This process in pseudocode is:</t> <t>This process in pseudocode is:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
initial_salt = 0x38762cf7f55934b34d179ae6a4c80cadccbb7f0a initial_salt = 0x38762cf7f55934b34d179ae6a4c80cadccbb7f0a
initial_secret = HKDF-Extract(initial_salt, initial_secret = HKDF-Extract(initial_salt,
client_dst_connection_id) client_dst_connection_id)
client_initial_secret = HKDF-Expand-Label(initial_secret, client_initial_secret = HKDF-Expand-Label(initial_secret,
"client in", "", "client in", "",
Hash.length) Hash.length)
server_initial_secret = HKDF-Expand-Label(initial_secret, server_initial_secret = HKDF-Expand-Label(initial_secret,
"server in", "", "server in", "",
Hash.length) Hash.length)
]]></artwork> ]]></artwork>
<t>The connection ID used with HKDF-Expand-Label is the Destination Conn ection ID <t>The connection ID used with HKDF-Expand-Label is the Destination Conn ection ID
in the Initial packet sent by the client. This will be a randomly-selected in the Initial packet sent by the client. This will be a randomly selected
value unless the client creates the Initial packet after receiving a Retry value unless the client creates the Initial packet after receiving a Retry
packet, where the Destination Connection ID is selected by the server.</t> packet, where the Destination Connection ID is selected by the server.</t>
<t>Future versions of QUIC SHOULD generate a new salt value, thus ensuri ng that <t>Future versions of QUIC <bcp14>SHOULD</bcp14> generate a new salt val ue, thus ensuring that
the keys are different for each version of QUIC. This prevents a middlebox that the keys are different for each version of QUIC. This prevents a middlebox that
recognizes only one version of QUIC from seeing or modifying the contents of recognizes only one version of QUIC from seeing or modifying the contents of
packets from future versions.</t> packets from future versions.</t>
<t>The HKDF-Expand-Label function defined in TLS 1.3 MUST be used for In itial <t>The HKDF-Expand-Label function defined in TLS 1.3 <bcp14>MUST</bcp14> be used for Initial
packets even where the TLS versions offered do not include TLS 1.3.</t> packets even where the TLS versions offered do not include TLS 1.3.</t>
<t>The secrets used for constructing subsequent Initial packets change w hen a <t>The secrets used for constructing subsequent Initial packets change w hen a
server sends a Retry packet, to use the connection ID value selected by the server sends a Retry packet to use the connection ID value selected by the
server. The secrets do not change when a client changes the Destination server. The secrets do not change when a client changes the Destination
Connection ID it uses in response to an Initial packet from the server.</t> Connection ID it uses in response to an Initial packet from the server.</t>
<dl> <aside>
<dt> <t>Note: The Destination Connection ID field could be any length up to
Note: </dt> 20 bytes,
<dd> including zero length if the server sends a Retry packet with a zero-length
<t>The Destination Connection ID field could be any length up to 20 Source Connection ID field. After a Retry, the Initial keys provide the client
bytes, no assurance that the server received its packet, so the client has to rely on
including zero length if the server sends a Retry packet with a zero-length the exchange that included the Retry packet to validate the server address;
Source Connection ID field. After a Retry, the Initial keys provide the client see <xref section="8.1" sectionFormat="of" target="QUIC-TRANSPORT" format="def
no assurance that the server received its packet, so the client has to rely on ault"/>.</t>
the exchange that included the Retry packet to validate the server address; </aside>
see Section 8.1 of <xref target="QUIC-TRANSPORT" format="default"/>.</t>
</dd>
</dl>
<t><xref target="test-vectors" format="default"/> contains sample Initia l packets.</t> <t><xref target="test-vectors" format="default"/> contains sample Initia l packets.</t>
</section> </section>
<section anchor="aead" numbered="true" toc="default"> <section anchor="aead" numbered="true" toc="default">
<name>AEAD Usage</name> <name>AEAD Usage</name>
<t>The Authenticated Encryption with Associated Data (AEAD; see <xref ta <t>The Authenticated Encryption with Associated Data (AEAD) function (se
rget="AEAD" format="default"/>) function e
used for QUIC packet protection is the AEAD that is negotiated for use with the <xref target="AEAD" format="default"/>) used for QUIC packet protection is the A
TLS connection. For example, if TLS is using the TLS_AES_128_GCM_SHA256 cipher EAD that is negotiated for
suite, the AEAD_AES_128_GCM function is used.</t> use with the TLS connection. For example, if TLS is using the
TLS_AES_128_GCM_SHA256 cipher suite, the AEAD_AES_128_GCM function is used.</t>
<t>QUIC can use any of the cipher suites defined in <xref target="TLS13" format="default"/> with the exception <t>QUIC can use any of the cipher suites defined in <xref target="TLS13" format="default"/> with the exception
of TLS_AES_128_CCM_8_SHA256. A cipher suite MUST NOT be negotiated unless a of TLS_AES_128_CCM_8_SHA256. A cipher suite <bcp14>MUST NOT</bcp14> be negotiat ed unless a
header protection scheme is defined for the cipher suite. This document defines header protection scheme is defined for the cipher suite. This document defines
a header protection scheme for all cipher suites defined in <xref target="TLS13" format="default"/> aside a header protection scheme for all cipher suites defined in <xref target="TLS13" format="default"/> aside
from TLS_AES_128_CCM_8_SHA256. These cipher suites have a 16-byte from TLS_AES_128_CCM_8_SHA256. These cipher suites have a 16-byte
authentication tag and produce an output 16 bytes larger than their input.</t> authentication tag and produce an output 16 bytes larger than their input.</t>
<dl> <t>An endpoint <bcp14>MUST NOT</bcp14> reject a ClientHello that offers
<dt> a cipher suite that it
Note: </dt> does not support, or it would be impossible to deploy a new cipher suite. This
<dd> also applies to TLS_AES_128_CCM_8_SHA256.</t>
<t>An endpoint MUST NOT reject a ClientHello that offers a cipher su
ite that it
does not support, or it would be impossible to deploy a new cipher suite.
This also applies to TLS_AES_128_CCM_8_SHA256.</t>
</dd>
</dl>
<t>When constructing packets, the AEAD function is applied prior to appl ying <t>When constructing packets, the AEAD function is applied prior to appl ying
header protection; see <xref target="header-protect" format="default"/>. The unp rotected packet header is part header protection; see <xref target="header-protect" format="default"/>. The unp rotected packet header is part
of the associated data (A). When processing packets, an endpoint first of the associated data (A). When processing packets, an endpoint first
removes the header protection.</t> removes the header protection.</t>
<t>The key and IV for the packet are computed as described in <xref targ et="protection-keys" format="default"/>. <t>The key and IV for the packet are computed as described in <xref targ et="protection-keys" format="default"/>.
The nonce, N, is formed by combining the packet protection IV with the packet The nonce, N, is formed by combining the packet protection IV with the packet
number. The 62 bits of the reconstructed QUIC packet number in network byte number. The 62 bits of the reconstructed QUIC packet number in network byte
order are left-padded with zeros to the size of the IV. The exclusive OR of the order are left-padded with zeros to the size of the IV. The exclusive OR of the
padded packet number and the IV forms the AEAD nonce.</t> padded packet number and the IV forms the AEAD nonce.</t>
<t>The associated data, A, for the AEAD is the contents of the QUIC head er, <t>The associated data, A, for the AEAD is the contents of the QUIC head er,
starting from the first byte of either the short or long header, up to and starting from the first byte of either the short or long header, up to and
including the unprotected packet number.</t> including the unprotected packet number.</t>
<t>The input plaintext, P, for the AEAD is the payload of the QUIC packe t, as <t>The input plaintext, P, for the AEAD is the payload of the QUIC packe t, as
described in <xref target="QUIC-TRANSPORT" format="default"/>.</t> described in <xref target="QUIC-TRANSPORT" format="default"/>.</t>
<t>The output ciphertext, C, of the AEAD is transmitted in place of P.</ t> <t>The output ciphertext, C, of the AEAD is transmitted in place of P.</ t>
<t>Some AEAD functions have limits for how many packets can be encrypted under the <t>Some AEAD functions have limits for how many packets can be encrypted under the
same key and IV; see <xref target="aead-limits" format="default"/>. This might be lower than the packet same key and IV; see <xref target="aead-limits" format="default"/>. This might be lower than the packet
number limit. An endpoint MUST initiate a key update (<xref target="key-update" format="default"/>) prior to number limit. An endpoint <bcp14>MUST</bcp14> initiate a key update (<xref targ et="key-update" format="default"/>) prior to
exceeding any limit set for the AEAD that is in use.</t> exceeding any limit set for the AEAD that is in use.</t>
</section> </section>
<section anchor="header-protect" numbered="true" toc="default"> <section anchor="header-protect" numbered="true" toc="default">
<name>Header Protection</name> <name>Header Protection</name>
<t>Parts of QUIC packet headers, in particular the Packet Number field, are <t>Parts of QUIC packet headers, in particular the Packet Number field, are
protected using a key that is derived separately from the packet protection key protected using a key that is derived separately from the packet protection key
and IV. The key derived using the "quic hp" label is used to provide and IV. The key derived using the "quic hp" label is used to provide
confidentiality protection for those fields that are not exposed to on-path confidentiality protection for those fields that are not exposed to on-path
elements.</t> elements.</t>
<t>This protection applies to the least-significant bits of the first by <t>This protection applies to the least significant bits of the first by
te, plus te, plus
the Packet Number field. The four least-significant bits of the first byte are the Packet Number field. The four least significant bits of the first byte are
protected for packets with long headers; the five least significant bits of the protected for packets with long headers; the five least significant bits of the
first byte are protected for packets with short headers. For both header forms, first byte are protected for packets with short headers. For both header forms,
this covers the reserved bits and the Packet Number Length field; the Key Phase this covers the reserved bits and the Packet Number Length field; the Key Phase
bit is also protected for packets with a short header.</t> bit is also protected for packets with a short header.</t>
<t>The same header protection key is used for the duration of the connec tion, with <t>The same header protection key is used for the duration of the connec tion, with
the value not changing after a key update (see <xref target="key-update" format= "default"/>). This allows the value not changing after a key update (see <xref target="key-update" format= "default"/>). This allows
header protection to be used to protect the key phase.</t> header protection to be used to protect the key phase.</t>
<t>This process does not apply to Retry or Version Negotiation packets, which do <t>This process does not apply to Retry or Version Negotiation packets, which do
not contain a protected payload or any of the fields that are protected by this not contain a protected payload or any of the fields that are protected by this
process.</t> process.</t>
skipping to change at line 957 skipping to change at line 926
<t>Header protection is applied after packet protection is applied (se e <xref target="aead" format="default"/>). <t>Header protection is applied after packet protection is applied (se e <xref target="aead" format="default"/>).
The ciphertext of the packet is sampled and used as input to an encryption The ciphertext of the packet is sampled and used as input to an encryption
algorithm. The algorithm used depends on the negotiated AEAD.</t> algorithm. The algorithm used depends on the negotiated AEAD.</t>
<t>The output of this algorithm is a 5-byte mask that is applied to th e protected <t>The output of this algorithm is a 5-byte mask that is applied to th e protected
header fields using exclusive OR. The least significant bits of the first byte header fields using exclusive OR. The least significant bits of the first byte
of the packet are masked by the least significant bits of the first mask byte, of the packet are masked by the least significant bits of the first mask byte,
and the packet number is masked with the remaining bytes. Any unused bytes of and the packet number is masked with the remaining bytes. Any unused bytes of
mask that might result from a shorter packet number encoding are unused.</t> mask that might result from a shorter packet number encoding are unused.</t>
<t><xref target="pseudo-hp" format="default"/> shows a sample algorith m for applying header protection. Removing <t><xref target="pseudo-hp" format="default"/> shows a sample algorith m for applying header protection. Removing
header protection only differs in the order in which the packet number length header protection only differs in the order in which the packet number length
(pn_length) is determined (here "^" is used to represent exclusive or).</t> (pn_length) is determined (here "^" is used to represent exclusive OR).</t>
<figure anchor="pseudo-hp"> <figure anchor="pseudo-hp">
<name>Header Protection Pseudocode</name> <name>Header Protection Pseudocode</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
mask = header_protection(hp_key, sample) mask = header_protection(hp_key, sample)
pn_length = (packet[0] & 0x03) + 1 pn_length = (packet[0] & 0x03) + 1
if (packet[0] & 0x80) == 0x80: if (packet[0] & 0x80) == 0x80:
# Long header: 4 bits masked # Long header: 4 bits masked
packet[0] ^= mask[0] & 0x0f packet[0] ^= mask[0] & 0x0f
else: else:
# Short header: 5 bits masked # Short header: 5 bits masked
packet[0] ^= mask[0] & 0x1f packet[0] ^= mask[0] & 0x1f
# pn_offset is the start of the Packet Number field. # pn_offset is the start of the Packet Number field.
packet[pn_offset:pn_offset+pn_length] ^= mask[1:1+pn_length] packet[pn_offset:pn_offset+pn_length] ^= mask[1:1+pn_length]
]]></artwork> ]]></sourcecode>
</figure> </figure>
<t>Specific header protection functions are defined based on the selec ted cipher <t>Specific header protection functions are defined based on the selec ted cipher
suite; see <xref target="hp-aes" format="default"/> and <xref target="hp-chacha" format="default"/>.</t> suite; see <xref target="hp-aes" format="default"/> and <xref target="hp-chacha" format="default"/>.</t>
<t><xref target="fig-sample" format="default"/> shows an example long header packet (Initial) and a short header <t><xref target="fig-sample" format="default"/> shows an example long header packet (Initial) and a short header
packet (1-RTT). <xref target="fig-sample" format="default"/> shows the fields in each header that are covered packet (1-RTT). <xref target="fig-sample" format="default"/> shows the fields in each header that are covered
by header protection and the portion of the protected packet payload that is by header protection and the portion of the protected packet payload that is
sampled.</t> sampled.</t>
<figure anchor="fig-sample"> <figure anchor="fig-sample">
<name>Header Protection and Ciphertext Sample</name> <name>Header Protection and Ciphertext Sample</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
skipping to change at line 1020 skipping to change at line 989
Packet Number Length (2), # Protected Packet Number Length (2), # Protected
Destination Connection ID (0..160), Destination Connection ID (0..160),
Packet Number (8..32), # Protected Packet Number (8..32), # Protected
Protected Payload (0..24), # Skipped Part Protected Payload (0..24), # Skipped Part
Protected Payload (128), # Sampled Part Protected Payload (128), # Sampled Part
Protected Payload (..), # Remainder Protected Payload (..), # Remainder
} }
]]></artwork> ]]></artwork>
</figure> </figure>
<t>Before a TLS cipher suite can be used with QUIC, a header protectio n algorithm <t>Before a TLS cipher suite can be used with QUIC, a header protectio n algorithm
MUST be specified for the AEAD used with that cipher suite. This document <bcp14>MUST</bcp14> be specified for the AEAD used with that cipher suite. This document
defines algorithms for AEAD_AES_128_GCM, AEAD_AES_128_CCM, AEAD_AES_256_GCM (all defines algorithms for AEAD_AES_128_GCM, AEAD_AES_128_CCM, AEAD_AES_256_GCM (all
these AES AEADs are defined in <xref target="AEAD" format="default"/>), and AEAD _CHACHA20_POLY1305 these AES AEADs are defined in <xref target="AEAD" format="default"/>), and AEAD _CHACHA20_POLY1305
(defined in <xref target="CHACHA" format="default"/>). Prior to TLS selecting a cipher suite, AES (defined in <xref target="CHACHA" format="default"/>). Prior to TLS selecting a cipher suite, AES
header protection is used (<xref target="hp-aes" format="default"/>), matching t he AEAD_AES_128_GCM packet header protection is used (<xref target="hp-aes" format="default"/>), matching t he AEAD_AES_128_GCM packet
protection.</t> protection.</t>
</section> </section>
<section anchor="hp-sample" numbered="true" toc="default"> <section anchor="hp-sample" numbered="true" toc="default">
<name>Header Protection Sample</name> <name>Header Protection Sample</name>
<t>The header protection algorithm uses both the header protection key and a sample <t>The header protection algorithm uses both the header protection key and a sample
of the ciphertext from the packet Payload field.</t> of the ciphertext from the packet Payload field.</t>
<t>The same number of bytes are always sampled, but an allowance needs to be made <t>The same number of bytes are always sampled, but an allowance needs to be made
for the endpoint removing protection, which will not know the length of the for the removal of protection by a receiving endpoint, which will not know the
Packet Number field. The sample of ciphertext is taken starting from an offset length of the Packet Number field. The sample of ciphertext is taken starting
of 4 bytes after the start of the Packet Number field. That is, in sampling from an offset of 4 bytes after the start of the Packet Number field. That is,
packet ciphertext for header protection, the Packet Number field is assumed to in sampling packet ciphertext for header protection, the Packet Number field is
be 4 bytes long (its maximum possible encoded length).</t> assumed to be 4 bytes long (its maximum possible encoded length).</t>
<t>An endpoint MUST discard packets that are not long enough to contai <t>An endpoint <bcp14>MUST</bcp14> discard packets that are not long e
n a complete nough to contain a complete
sample.</t> sample.</t>
<t>To ensure that sufficient data is available for sampling, packets a re padded so <t>To ensure that sufficient data is available for sampling, packets a re padded so
that the combined lengths of the encoded packet number and protected payload is that the combined lengths of the encoded packet number and protected payload is
at least 4 bytes longer than the sample required for header protection. The at least 4 bytes longer than the sample required for header protection. The
cipher suites defined in <xref target="TLS13" format="default"/> - other than TL cipher suites defined in <xref target="TLS13" format="default"/> -- other than T
S_AES_128_CCM_8_SHA256, for LS_AES_128_CCM_8_SHA256, for
which a header protection scheme is not defined in this document - have 16-byte which a header protection scheme is not defined in this document -- have 16-byte
expansions and 16-byte header protection samples. This results in needing at expansions and 16-byte header protection samples. This results in needing at
least 3 bytes of frames in the unprotected payload if the packet number is least 3 bytes of frames in the unprotected payload if the packet number is
encoded on a single byte, or 2 bytes of frames for a 2-byte packet number encoded on a single byte, or 2 bytes of frames for a 2-byte packet number
encoding.</t> encoding.</t>
<t>The sampled ciphertext can be determined by the following pseudocod e:</t> <t>The sampled ciphertext can be determined by the following pseudocod e:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
# pn_offset is the start of the Packet Number field. # pn_offset is the start of the Packet Number field.
sample_offset = pn_offset + 4 sample_offset = pn_offset + 4
sample = packet[sample_offset..sample_offset+sample_length] sample = packet[sample_offset..sample_offset+sample_length]
]]></artwork> ]]></sourcecode>
<t>where the packet number offset of a short header packet can be calc <t>Where the packet number offset of a short header packet can be calc
ulated as:</t> ulated as:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
pn_offset = 1 + len(connection_id) pn_offset = 1 + len(connection_id)
]]></artwork> ]]></sourcecode>
<t>and the packet number offset of a long header packet can be calcula <t>And the packet number offset of a long header packet can be calcula
ted as:</t> ted as:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
pn_offset = 7 + len(destination_connection_id) + pn_offset = 7 + len(destination_connection_id) +
len(source_connection_id) + len(source_connection_id) +
len(payload_length) len(payload_length)
if packet_type == Initial: if packet_type == Initial:
pn_offset += len(token_length) + pn_offset += len(token_length) +
len(token) len(token)
]]></artwork> ]]></sourcecode>
<t>For example, for a packet with a short header, an 8-byte connection ID, and <t>For example, for a packet with a short header, an 8-byte connection ID, and
protected with AEAD_AES_128_GCM, the sample takes bytes 13 to 28 inclusive protected with AEAD_AES_128_GCM, the sample takes bytes 13 to 28 inclusive
(using zero-based indexing).</t> (using zero-based indexing).</t>
<t>Multiple QUIC packets might be included in the same UDP datagram. E ach packet <t>Multiple QUIC packets might be included in the same UDP datagram. E ach packet
is handled separately.</t> is handled separately.</t>
</section> </section>
<section anchor="hp-aes" numbered="true" toc="default"> <section anchor="hp-aes" numbered="true" toc="default">
<name>AES-Based Header Protection</name> <name>AES-Based Header Protection</name>
<t>This section defines the packet protection algorithm for AEAD_AES_1 28_GCM, <t>This section defines the packet protection algorithm for AEAD_AES_1 28_GCM,
AEAD_AES_128_CCM, and AEAD_AES_256_GCM. AEAD_AES_128_GCM and AEAD_AES_128_CCM AEAD_AES_128_CCM, and AEAD_AES_256_GCM. AEAD_AES_128_GCM and AEAD_AES_128_CCM
use 128-bit AES in electronic code-book (ECB) mode. AEAD_AES_256_GCM uses use 128-bit AES in Electronic Codebook (ECB) mode. AEAD_AES_256_GCM uses
256-bit AES in ECB mode. AES is defined in <xref target="AES" format="default"/ >.</t> 256-bit AES in ECB mode. AES is defined in <xref target="AES" format="default"/ >.</t>
<t>This algorithm samples 16 bytes from the packet ciphertext. This va lue is used <t>This algorithm samples 16 bytes from the packet ciphertext. This va lue is used
as the input to AES-ECB. In pseudocode, the header protection function is as the input to AES-ECB. In pseudocode, the header protection function is
defined as:</t> defined as:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
header_protection(hp_key, sample): header_protection(hp_key, sample):
mask = AES-ECB(hp_key, sample) mask = AES-ECB(hp_key, sample)
]]></artwork> ]]></sourcecode>
</section> </section>
<section anchor="hp-chacha" numbered="true" toc="default"> <section anchor="hp-chacha" numbered="true" toc="default">
<name>ChaCha20-Based Header Protection</name> <name>ChaCha20-Based Header Protection</name>
<t>When AEAD_CHACHA20_POLY1305 is in use, header protection uses the r aw ChaCha20 <t>When AEAD_CHACHA20_POLY1305 is in use, header protection uses the r aw ChaCha20
function as defined in Section 2.4 of <xref target="CHACHA" format="default"/>. This uses a 256-bit key and function as defined in <xref section="2.4" sectionFormat="of" target="CHACHA" fo rmat="default"/>. This uses a 256-bit key and
16 bytes sampled from the packet protection output.</t> 16 bytes sampled from the packet protection output.</t>
<t>The first 4 bytes of the sampled ciphertext are the block counter. A ChaCha20 <t>The first 4 bytes of the sampled ciphertext are the block counter. A ChaCha20
implementation could take a 32-bit integer in place of a byte sequence, in implementation could take a 32-bit integer in place of a byte sequence, in
which case the byte sequence is interpreted as a little-endian value.</t> which case, the byte sequence is interpreted as a little-endian value.</t>
<t>The remaining 12 bytes are used as the nonce. A ChaCha20 implementa tion might <t>The remaining 12 bytes are used as the nonce. A ChaCha20 implementa tion might
take an array of three 32-bit integers in place of a byte sequence, in which take an array of three 32-bit integers in place of a byte sequence, in which
case the nonce bytes are interpreted as a sequence of 32-bit little-endian case, the nonce bytes are interpreted as a sequence of 32-bit little-endian
integers.</t> integers.</t>
<t>The encryption mask is produced by invoking ChaCha20 to protect 5 z ero bytes. In <t>The encryption mask is produced by invoking ChaCha20 to protect 5 z ero bytes. In
pseudocode, the header protection function is defined as:</t> pseudocode, the header protection function is defined as:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
header_protection(hp_key, sample): header_protection(hp_key, sample):
counter = sample[0..3] counter = sample[0..3]
nonce = sample[4..15] nonce = sample[4..15]
mask = ChaCha20(hp_key, counter, nonce, {0,0,0,0,0}) mask = ChaCha20(hp_key, counter, nonce, {0,0,0,0,0})
]]></artwork> ]]></sourcecode>
</section> </section>
</section> </section>
<section anchor="receiving-protected-packets" numbered="true" toc="default "> <section anchor="receiving-protected-packets" numbered="true" toc="default ">
<name>Receiving Protected Packets</name> <name>Receiving Protected Packets</name>
<t>Once an endpoint successfully receives a packet with a given packet n umber, it <t>Once an endpoint successfully receives a packet with a given packet n umber, it
MUST discard all packets in the same packet number space with higher packet <bcp14>MUST</bcp14> discard all packets in the same packet number space with hig her packet
numbers if they cannot be successfully unprotected with either the same key, or numbers if they cannot be successfully unprotected with either the same key, or
- if there is a key update - a subsequent packet protection key; see -- if there is a key update -- a subsequent packet protection key; see
<xref target="key-update" format="default"/>. Similarly, a packet that appears <xref target="key-update" format="default"/>. Similarly, a packet that appears
to trigger a key update, but to trigger a key update but
cannot be unprotected successfully MUST be discarded.</t> cannot be unprotected successfully <bcp14>MUST</bcp14> be discarded.</t>
<t>Failure to unprotect a packet does not necessarily indicate the exist ence of a <t>Failure to unprotect a packet does not necessarily indicate the exist ence of a
protocol error in a peer or an attack. The truncated packet number encoding protocol error in a peer or an attack. The truncated packet number encoding
used in QUIC can cause packet numbers to be decoded incorrectly if they are used in QUIC can cause packet numbers to be decoded incorrectly if they are
delayed significantly.</t> delayed significantly.</t>
</section> </section>
<section anchor="using-early-data" numbered="true" toc="default"> <section anchor="using-early-data" numbered="true" toc="default">
<name>Use of 0-RTT Keys</name> <name>Use of 0-RTT Keys</name>
<t>If 0-RTT keys are available (see <xref target="enable-0rtt" format="d efault"/>), the lack of replay protection <t>If 0-RTT keys are available (see <xref target="enable-0rtt" format="d efault"/>), the lack of replay protection
means that restrictions on their use are necessary to avoid replay attacks on means that restrictions on their use are necessary to avoid replay attacks on
the protocol.</t> the protocol.</t>
<t>Of the frames defined in <xref target="QUIC-TRANSPORT" format="defaul t"/>, the STREAM, RESET_STREAM, <t>Of the frames defined in <xref target="QUIC-TRANSPORT" format="defaul t"/>, the STREAM, RESET_STREAM,
STOP_SENDING, and CONNECTION_CLOSE frames are potentially unsafe for use with STOP_SENDING, and CONNECTION_CLOSE frames are potentially unsafe for use with
0-RTT as they carry application data. Application data that is received in 0-RTT as they carry application data. Application data that is received in
0-RTT could cause an application at the server to process the data multiple 0-RTT could cause an application at the server to process the data multiple
times rather than just once. Additional actions taken by a server as a result times rather than just once. Additional actions taken by a server as a result
of processing replayed application data could have unwanted consequences. A of processing replayed application data could have unwanted consequences. A
client therefore MUST NOT use 0-RTT for application data unless specifically client therefore <bcp14>MUST NOT</bcp14> use 0-RTT for application data unless s pecifically
requested by the application that is in use.</t> requested by the application that is in use.</t>
<t>An application protocol that uses QUIC MUST include a profile that de fines <t>An application protocol that uses QUIC <bcp14>MUST</bcp14> include a profile that defines
acceptable use of 0-RTT; otherwise, 0-RTT can only be used to carry QUIC frames acceptable use of 0-RTT; otherwise, 0-RTT can only be used to carry QUIC frames
that do not carry application data. For example, a profile for HTTP is that do not carry application data. For example, a profile for HTTP is
described in <xref target="HTTP-REPLAY" format="default"/> and used for HTTP/3; described in <xref target="HTTP-REPLAY" format="default"/> and used for HTTP/3;
see Section 10.9 of see
<xref target="QUIC-HTTP" format="default"/>.</t> <xref section="10.9" sectionFormat="of" target="QUIC-HTTP" format="default"/>.</
t>
<t>Though replaying packets might result in additional connection attemp ts, the <t>Though replaying packets might result in additional connection attemp ts, the
effect of processing replayed frames that do not carry application data is effect of processing replayed frames that do not carry application data is
limited to changing the state of the affected connection. A TLS handshake limited to changing the state of the affected connection. A TLS handshake
cannot be successfully completed using replayed packets.</t> cannot be successfully completed using replayed packets.</t>
<t>A client MAY wish to apply additional restrictions on what data it se nds prior <t>A client <bcp14>MAY</bcp14> wish to apply additional restrictions on what data it sends prior
to the completion of the TLS handshake.</t> to the completion of the TLS handshake.</t>
<t>A client otherwise treats 0-RTT keys as equivalent to 1-RTT keys, exc ept that <t>A client otherwise treats 0-RTT keys as equivalent to 1-RTT keys, exc ept that
it cannot send certain frames with 0-RTT keys; see Section 12.5 of it cannot send certain frames with 0-RTT keys; see
<xref target="QUIC-TRANSPORT" format="default"/>.</t> <xref section="12.5" sectionFormat="of" target="QUIC-TRANSPORT" format="default"
/>.</t>
<t>A client that receives an indication that its 0-RTT data has been acc epted by a <t>A client that receives an indication that its 0-RTT data has been acc epted by a
server can send 0-RTT data until it receives all of the server's handshake server can send 0-RTT data until it receives all of the server's handshake
messages. A client SHOULD stop sending 0-RTT data if it receives an indication messages. A client <bcp14>SHOULD</bcp14> stop sending 0-RTT data if it receives an indication
that 0-RTT data has been rejected.</t> that 0-RTT data has been rejected.</t>
<t>A server MUST NOT use 0-RTT keys to protect packets; it uses 1-RTT ke <t>A server <bcp14>MUST NOT</bcp14> use 0-RTT keys to protect packets; i
ys to t uses 1-RTT keys to
protect acknowledgments of 0-RTT packets. A client MUST NOT attempt to protect acknowledgments of 0-RTT packets. A client <bcp14>MUST NOT</bcp14> atte
decrypt 0-RTT packets it receives and instead MUST discard them.</t> mpt to
<t>Once a client has installed 1-RTT keys, it MUST NOT send any more 0-R decrypt 0-RTT packets it receives and instead <bcp14>MUST</bcp14> discard them.<
TT /t>
<t>Once a client has installed 1-RTT keys, it <bcp14>MUST NOT</bcp14> se
nd any more 0-RTT
packets.</t> packets.</t>
<dl> <aside>
<dt> <t>Note: 0-RTT data can be acknowledged by the server as it receives i
Note: </dt> t, but any
<dd> packets containing acknowledgments of 0-RTT data cannot have packet protection
<t>0-RTT data can be acknowledged by the server as it receives it, b removed by the client until the TLS handshake is complete. The 1-RTT keys
ut any necessary to remove packet protection cannot be derived until the client
packets containing acknowledgments of 0-RTT data cannot have packet protection receives all server handshake messages.</t>
removed by the client until the TLS handshake is complete. The 1-RTT keys </aside>
necessary to remove packet protection cannot be derived until the client
receives all server handshake messages.</t>
</dd>
</dl>
</section> </section>
<section anchor="pre-hs-protected" numbered="true" toc="default"> <section anchor="pre-hs-protected" numbered="true" toc="default">
<name>Receiving Out-of-Order Protected Packets</name> <name>Receiving Out-of-Order Protected Packets</name>
<t>Due to reordering and loss, protected packets might be received by an endpoint <t>Due to reordering and loss, protected packets might be received by an endpoint
before the final TLS handshake messages are received. A client will be unable before the final TLS handshake messages are received. A client will be unable
to decrypt 1-RTT packets from the server, whereas a server will be able to to decrypt 1-RTT packets from the server, whereas a server will be able to
decrypt 1-RTT packets from the client. Endpoints in either role MUST NOT decrypt 1-RTT packets from the client. Endpoints in either role <bcp14>MUST NOT </bcp14>
decrypt 1-RTT packets from their peer prior to completing the handshake.</t> decrypt 1-RTT packets from their peer prior to completing the handshake.</t>
<t>Even though 1-RTT keys are available to a server after receiving the first <t>Even though 1-RTT keys are available to a server after receiving the first
handshake messages from a client, it is missing assurances on the client state:< /t> handshake messages from a client, it is missing assurances on the client state:< /t>
<ul spacing="normal"> <ul spacing="normal">
<li>The client is not authenticated, unless the server has chosen to u se a <li>The client is not authenticated, unless the server has chosen to u se a
pre-shared key and validated the client's pre-shared key binder; see Section pre-shared key and validated the client's pre-shared key binder; see <xref secti
4.2.11 of <xref target="TLS13" format="default"/>.</li> on="4.2.11" sectionFormat="of" target="TLS13" format="default"/>.</li>
<li>The client has not demonstrated liveness, unless the server has va lidated the <li>The client has not demonstrated liveness, unless the server has va lidated the
client's address with a Retry packet or other means; see Section 8.1 of client's address with a Retry packet or other means; see
<xref target="QUIC-TRANSPORT" format="default"/>.</li> <xref section="8.1" sectionFormat="of" target="QUIC-TRANSPORT" format="default"/
>.</li>
<li>Any received 0-RTT data that the server responds to might be due t o a replay <li>Any received 0-RTT data that the server responds to might be due t o a replay
attack.</li> attack.</li>
</ul> </ul>
<t>Therefore, the server's use of 1-RTT keys before the handshake is com plete is <t>Therefore, the server's use of 1-RTT keys before the handshake is com plete is
limited to sending data. A server MUST NOT process incoming 1-RTT protected limited to sending data. A server <bcp14>MUST NOT</bcp14> process incoming 1-RT T protected
packets before the TLS handshake is complete. Because sending acknowledgments packets before the TLS handshake is complete. Because sending acknowledgments
indicates that all frames in a packet have been processed, a server cannot send indicates that all frames in a packet have been processed, a server cannot send
acknowledgments for 1-RTT packets until the TLS handshake is complete. Received acknowledgments for 1-RTT packets until the TLS handshake is complete. Received
packets protected with 1-RTT keys MAY be stored and later decrypted and used packets protected with 1-RTT keys <bcp14>MAY</bcp14> be stored and later decrypt ed and used
once the handshake is complete.</t> once the handshake is complete.</t>
<dl> <aside>
<dt> <t>Note: TLS implementations might provide all 1-RTT secrets prior to
Note: </dt> handshake
<dd> completion. Even where QUIC implementations have 1-RTT read keys, those keys
<t>TLS implementations might provide all 1-RTT secrets prior to hand are not to be used prior to completing the handshake.</t>
shake </aside>
completion. Even where QUIC implementations have 1-RTT read keys, those keys
are not to be used prior to completing the handshake.</t>
</dd>
</dl>
<t>The requirement for the server to wait for the client Finished messag e creates <t>The requirement for the server to wait for the client Finished messag e creates
a dependency on that message being delivered. A client can avoid the a dependency on that message being delivered. A client can avoid the
potential for head-of-line blocking that this implies by sending its 1-RTT potential for head-of-line blocking that this implies by sending its 1-RTT
packets coalesced with a Handshake packet containing a copy of the CRYPTO frame packets coalesced with a Handshake packet containing a copy of the CRYPTO frame
that carries the Finished message, until one of the Handshake packets is that carries the Finished message, until one of the Handshake packets is
acknowledged. This enables immediate server processing for those packets.</t> acknowledged. This enables immediate server processing for those packets.</t>
<t>A server could receive packets protected with 0-RTT keys prior to rec eiving a <t>A server could receive packets protected with 0-RTT keys prior to rec eiving a
TLS ClientHello. The server MAY retain these packets for later decryption in TLS ClientHello. The server <bcp14>MAY</bcp14> retain these packets for later d ecryption in
anticipation of receiving a ClientHello.</t> anticipation of receiving a ClientHello.</t>
<t>A client generally receives 1-RTT keys at the same time as the handsh ake <t>A client generally receives 1-RTT keys at the same time as the handsh ake
completes. Even if it has 1-RTT secrets, a client MUST NOT process completes. Even if it has 1-RTT secrets, a client <bcp14>MUST NOT</bcp14> proce ss
incoming 1-RTT protected packets before the TLS handshake is complete.</t> incoming 1-RTT protected packets before the TLS handshake is complete.</t>
</section> </section>
<section anchor="retry-integrity" numbered="true" toc="default"> <section anchor="retry-integrity" numbered="true" toc="default">
<name>Retry Packet Integrity</name> <name>Retry Packet Integrity</name>
<t>Retry packets (see the Retry Packet section of <xref target="QUIC-TRA <t>Retry packets (see <xref section="17.2.5" sectionFormat="of" target="
NSPORT" format="default"/>) carry a QUIC-TRANSPORT" format="default"/>) carry a Retry Integrity
Retry Integrity Tag that provides two properties: it allows discarding Tag that provides two properties: it allows the discarding of packets that have
packets that have accidentally been corrupted by the network; only an accidentally been corrupted by the network, and only an entity that observes an
entity that observes an Initial packet can send a valid Retry packet.</t> Initial packet can send a valid Retry packet.</t>
<t>The Retry Integrity Tag is a 128-bit field that is computed as the ou tput of <t>The Retry Integrity Tag is a 128-bit field that is computed as the ou tput of
AEAD_AES_128_GCM (<xref target="AEAD" format="default"/>) used with the followin g inputs:</t> AEAD_AES_128_GCM <xref target="AEAD" format="default"/> used with the following inputs:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>The secret key, K, is 128 bits equal to 0xbe0c690b9f66575a1d766b54 e368c84e.</li> <li>The secret key, K, is 128 bits equal to 0xbe0c690b9f66575a1d766b54 e368c84e.</li>
<li>The nonce, N, is 96 bits equal to 0x461599d35d632bf2239825bb.</li> <li>The nonce, N, is 96 bits equal to 0x461599d35d632bf2239825bb.</li>
<li>The plaintext, P, is empty.</li> <li>The plaintext, P, is empty.</li>
<li>The associated data, A, is the contents of the Retry Pseudo-Packet , as <li>The associated data, A, is the contents of the Retry Pseudo-Packet , as
illustrated in <xref target="retry-pseudo" format="default"/>:</li> illustrated in <xref target="retry-pseudo" format="default"/>:</li>
</ul> </ul>
<t>The secret key and the nonce are values derived by calling HKDF-Expan d-Label <t>The secret key and the nonce are values derived by calling HKDF-Expan d-Label
using 0xd9c9943e6101fd200021506bcc02814c73030f25c79d71ce876eca876e6fca8e as the using 0xd9c9943e6101fd200021506bcc02814c73030f25c79d71ce876eca876e6fca8e as the
secret, with labels being "quic key" and "quic iv" (<xref target="protection-key s" format="default"/>).</t> secret, with labels being "quic key" and "quic iv" (<xref target="protection-key s" format="default"/>).</t>
skipping to change at line 1257 skipping to change at line 1217
Version (32), Version (32),
DCID Len (8), DCID Len (8),
Destination Connection ID (0..160), Destination Connection ID (0..160),
SCID Len (8), SCID Len (8),
Source Connection ID (0..160), Source Connection ID (0..160),
Retry Token (..), Retry Token (..),
} }
]]></artwork> ]]></artwork>
</figure> </figure>
<t>The Retry Pseudo-Packet is not sent over the wire. It is computed by taking <t>The Retry Pseudo-Packet is not sent over the wire. It is computed by taking
the transmitted Retry packet, removing the Retry Integrity Tag and prepending the transmitted Retry packet, removing the Retry Integrity Tag, and prepending
the two following fields:</t> the two following fields:</t>
<dl> <dl>
<dt> <dt>ODCID Length:</dt>
ODCID Length: </dt>
<dd> <dd>
<t>The ODCID Length field contains the length in bytes of the Origin al <t>The ODCID Length field contains the length in bytes of the Origin al
Destination Connection ID field that follows it, encoded as an 8-bit unsigned Destination Connection ID field that follows it, encoded as an 8-bit unsigned
integer.</t> integer.</t>
</dd> </dd>
<dt> <dt>Original Destination Connection ID:</dt>
Original Destination Connection ID: </dt>
<dd> <dd>
<t>The Original Destination Connection ID contains the value of the Destination <t>The Original Destination Connection ID contains the value of the Destination
Connection ID from the Initial packet that this Retry is in response to. The Connection ID from the Initial packet that this Retry is in response to. The
length of this field is given in ODCID Length. The presence of this field length of this field is given in ODCID Length. The presence of this field
ensures that a valid Retry packet can only be sent by an entity that ensures that a valid Retry packet can only be sent by an entity that
observes the Initial packet.</t> observes the Initial packet.</t>
</dd> </dd>
</dl> </dl>
</section> </section>
</section> </section>
<section anchor="key-update" numbered="true" toc="default"> <section anchor="key-update" numbered="true" toc="default">
<name>Key Update</name> <name>Key Update</name>
<t>Once the handshake is confirmed (see <xref target="handshake-confirmed" format="default"/>), an endpoint MAY <t>Once the handshake is confirmed (see <xref target="handshake-confirmed" format="default"/>), an endpoint <bcp14>MAY</bcp14>
initiate a key update.</t> initiate a key update.</t>
<t>The Key Phase bit indicates which packet protection keys are used to pr otect the <t>The Key Phase bit indicates which packet protection keys are used to pr otect the
packet. The Key Phase bit is initially set to 0 for the first set of 1-RTT packet. The Key Phase bit is initially set to 0 for the first set of 1-RTT
packets and toggled to signal each subsequent key update.</t> packets and toggled to signal each subsequent key update.</t>
<t>The Key Phase bit allows a recipient to detect a change in keying mater ial <t>The Key Phase bit allows a recipient to detect a change in keying mater ial
without needing to receive the first packet that triggered the change. An without needing to receive the first packet that triggered the change. An
endpoint that notices a changed Key Phase bit updates keys and decrypts the endpoint that notices a changed Key Phase bit updates keys and decrypts the
packet that contains the changed value.</t> packet that contains the changed value.</t>
<t>Initiating a key update results in both endpoints updating keys. This differs <t>Initiating a key update results in both endpoints updating keys. This differs
from TLS where endpoints can update keys independently.</t> from TLS where endpoints can update keys independently.</t>
<t>This mechanism replaces the key update mechanism of TLS, which relies o n <t>This mechanism replaces the key update mechanism of TLS, which relies o n
KeyUpdate messages sent using 1-RTT encryption keys. Endpoints MUST NOT send a KeyUpdate messages sent using 1-RTT encryption keys. Endpoints <bcp14>MUST NOT<
TLS KeyUpdate message. Endpoints MUST treat the receipt of a TLS KeyUpdate /bcp14> send a
message as a connection error of type 0x10a, equivalent to a TLS KeyUpdate message. Endpoints <bcp14>MUST</bcp14> treat the receipt of a TLS
KeyUpdate
message as a connection error of type 0x010a, equivalent to a
fatal TLS alert of unexpected_message; see <xref target="tls-errors" format="def ault"/>.</t> fatal TLS alert of unexpected_message; see <xref target="tls-errors" format="def ault"/>.</t>
<t><xref target="ex-key-update" format="default"/> shows a key update proc ess, where the initial set of keys used <t><xref target="ex-key-update" format="default"/> shows a key update proc ess, where the initial set of keys used
(identified with @M) are replaced by updated keys (identified with @N). The (identified with @M) are replaced by updated keys (identified with @N). The
value of the Key Phase bit is indicated in brackets [].</t> value of the Key Phase bit is indicated in brackets [].</t>
<figure anchor="ex-key-update"> <figure anchor="ex-key-update">
<name>Key Update</name> <name>Key Update</name>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
Initiating Peer Responding Peer Initiating Peer Responding Peer
@M [0] QUIC Packets @M [0] QUIC Packets
skipping to change at line 1329 skipping to change at line 1287
containing ACK for @N packets containing ACK for @N packets
--------> -------->
Key Update Permitted ... Key Update Permitted ...
]]></artwork> ]]></artwork>
</figure> </figure>
<section anchor="key-update-initiate" numbered="true" toc="default"> <section anchor="key-update-initiate" numbered="true" toc="default">
<name>Initiating a Key Update</name> <name>Initiating a Key Update</name>
<t>Endpoints maintain separate read and write secrets for packet protect ion. An <t>Endpoints maintain separate read and write secrets for packet protect ion. An
endpoint initiates a key update by updating its packet protection write secret endpoint initiates a key update by updating its packet protection write secret
and using that to protect new packets. The endpoint creates a new write secret and using that to protect new packets. The endpoint creates a new write secret
from the existing write secret as performed in Section 7.2 of <xref target="TLS1 3" format="default"/>. This from the existing write secret as performed in <xref section="7.2" sectionFormat ="of" target="TLS13" format="default"/>. This
uses the KDF function provided by TLS with a label of "quic ku". The uses the KDF function provided by TLS with a label of "quic ku". The
corresponding key and IV are created from that secret as defined in corresponding key and IV are created from that secret as defined in
<xref target="protection-keys" format="default"/>. The header protection key is not updated.</t> <xref target="protection-keys" format="default"/>. The header protection key is not updated.</t>
<t>For example, to update write keys with TLS 1.3, HKDF-Expand-Label is used as:</t> <t>For example, to update write keys with TLS 1.3, HKDF-Expand-Label is used as:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
secret_<n+1> = HKDF-Expand-Label(secret_<n>, "quic ku", secret_<n+1> = HKDF-Expand-Label(secret_<n>, "quic ku",
"", Hash.length) "", Hash.length)
]]></artwork> ]]></sourcecode>
<t>The endpoint toggles the value of the Key Phase bit and uses the upda ted key and <t>The endpoint toggles the value of the Key Phase bit and uses the upda ted key and
IV to protect all subsequent packets.</t> IV to protect all subsequent packets.</t>
<t>An endpoint MUST NOT initiate a key update prior to having confirmed <t>An endpoint <bcp14>MUST NOT</bcp14> initiate a key update prior to ha
the ving confirmed the
handshake (<xref target="handshake-confirmed" format="default"/>). An endpoint handshake (<xref target="handshake-confirmed" format="default"/>). An endpoint
MUST NOT initiate a subsequent <bcp14>MUST NOT</bcp14> initiate a subsequent
key update unless it has received an acknowledgment for a packet that was sent key update unless it has received an acknowledgment for a packet that was sent
protected with keys from the current key phase. This ensures that keys are protected with keys from the current key phase. This ensures that keys are
available to both peers before another key update can be initiated. This can be available to both peers before another key update can be initiated. This can be
implemented by tracking the lowest packet number sent with each key phase, and implemented by tracking the lowest packet number sent with each key phase and
the highest acknowledged packet number in the 1-RTT space: once the latter is the highest acknowledged packet number in the 1-RTT space: once the latter is
higher than or equal to the former, another key update can be initiated.</t> higher than or equal to the former, another key update can be initiated.</t>
<dl> <aside>
<dt> <t>Note: Keys of packets other than the 1-RTT packets are never update
Note: </dt> d; their keys
<dd> are derived solely from the TLS handshake state.</t>
<t>Keys of packets other than the 1-RTT packets are never updated; t </aside>
heir keys are
derived solely from the TLS handshake state.</t>
</dd>
</dl>
<t>The endpoint that initiates a key update also updates the keys that i t uses for <t>The endpoint that initiates a key update also updates the keys that i t uses for
receiving packets. These keys will be needed to process packets the peer sends receiving packets. These keys will be needed to process packets the peer sends
after updating.</t> after updating.</t>
<t>An endpoint MUST retain old keys until it has successfully unprotecte <t>An endpoint <bcp14>MUST</bcp14> retain old keys until it has successf
d a packet ully unprotected a packet
sent using the new keys. An endpoint SHOULD retain old keys for some time sent using the new keys. An endpoint <bcp14>SHOULD</bcp14> retain old keys for
some time
after unprotecting a packet sent using the new keys. Discarding old keys too after unprotecting a packet sent using the new keys. Discarding old keys too
early can cause delayed packets to be discarded. Discarding packets will be early can cause delayed packets to be discarded. Discarding packets will be
interpreted as packet loss by the peer and could adversely affect performance.</ t> interpreted as packet loss by the peer and could adversely affect performance.</ t>
</section> </section>
<section anchor="responding-to-a-key-update" numbered="true" toc="default" > <section anchor="responding-to-a-key-update" numbered="true" toc="default" >
<name>Responding to a Key Update</name> <name>Responding to a Key Update</name>
<t>A peer is permitted to initiate a key update after receiving an ackno wledgment <t>A peer is permitted to initiate a key update after receiving an ackno wledgment
of a packet in the current key phase. An endpoint detects a key update when of a packet in the current key phase. An endpoint detects a key update when
processing a packet with a key phase that differs from the value used to protect processing a packet with a key phase that differs from the value used to protect
the last packet it sent. To process this packet, the endpoint uses the next the last packet it sent. To process this packet, the endpoint uses the next
packet protection key and IV. See <xref target="receive-key-generation" format= "default"/> for considerations packet protection key and IV. See <xref target="receive-key-generation" format= "default"/> for considerations
about generating these keys.</t> about generating these keys.</t>
<t>If a packet is successfully processed using the next key and IV, then the peer <t>If a packet is successfully processed using the next key and IV, then the peer
has initiated a key update. The endpoint MUST update its send keys to the has initiated a key update. The endpoint <bcp14>MUST</bcp14> update its send ke ys to the
corresponding key phase in response, as described in <xref target="key-update-in itiate" format="default"/>. corresponding key phase in response, as described in <xref target="key-update-in itiate" format="default"/>.
Sending keys MUST be updated before sending an acknowledgment for the packet Sending keys <bcp14>MUST</bcp14> be updated before sending an acknowledgment for the packet
that was received with updated keys. By acknowledging the packet that triggered that was received with updated keys. By acknowledging the packet that triggered
the key update in a packet protected with the updated keys, the endpoint signals the key update in a packet protected with the updated keys, the endpoint signals
that the key update is complete.</t> that the key update is complete.</t>
<t>An endpoint can defer sending the packet or acknowledgment according to its <t>An endpoint can defer sending the packet or acknowledgment according to its
normal packet sending behaviour; it is not necessary to immediately generate a normal packet sending behavior; it is not necessary to immediately generate a
packet in response to a key update. The next packet sent by the endpoint will packet in response to a key update. The next packet sent by the endpoint will
use the updated keys. The next packet that contains an acknowledgment will use the updated keys. The next packet that contains an acknowledgment will
cause the key update to be completed. If an endpoint detects a second update cause the key update to be completed. If an endpoint detects a second update
before it has sent any packets with updated keys containing an before it has sent any packets with updated keys containing an
acknowledgment for the packet that initiated the key update, it indicates that acknowledgment for the packet that initiated the key update, it indicates that
its peer has updated keys twice without awaiting confirmation. An endpoint MAY its peer has updated keys twice without awaiting confirmation. An endpoint <bcp 14>MAY</bcp14>
treat such consecutive key updates as a connection error of type treat such consecutive key updates as a connection error of type
KEY_UPDATE_ERROR.</t> KEY_UPDATE_ERROR.</t>
<t>An endpoint that receives an acknowledgment that is carried in a pack et <t>An endpoint that receives an acknowledgment that is carried in a pack et
protected with old keys where any acknowledged packet was protected with newer protected with old keys where any acknowledged packet was protected with newer
keys MAY treat that as a connection error of type KEY_UPDATE_ERROR. This keys <bcp14>MAY</bcp14> treat that as a connection error of type KEY_UPDATE_ERRO R. This
indicates that a peer has received and acknowledged a packet that initiates a indicates that a peer has received and acknowledged a packet that initiates a
key update, but has not updated keys in response.</t> key update, but has not updated keys in response.</t>
</section> </section>
<section anchor="receive-key-generation" numbered="true" toc="default"> <section anchor="receive-key-generation" numbered="true" toc="default">
<name>Timing of Receive Key Generation</name> <name>Timing of Receive Key Generation</name>
<t>Endpoints responding to an apparent key update MUST NOT generate a ti ming <t>Endpoints responding to an apparent key update <bcp14>MUST NOT</bcp14 > generate a timing
side-channel signal that might indicate that the Key Phase bit was invalid (see side-channel signal that might indicate that the Key Phase bit was invalid (see
<xref target="header-protect-analysis" format="default"/>). Endpoints can use d <xref target="hp-side-channel" format="default"/>). Endpoints can use randomize
ummy packet protection keys in d packet protection keys in
place of discarded keys when key updates are not yet permitted. Using dummy place of discarded keys when key updates are not yet permitted. Using
keys will generate no variation in the timing signal produced by attempting to randomized keys ensures that attempting to remove packet protection does not
remove packet protection, and results in all packets with an invalid Key Phase result in timing variations, and results in packets with an invalid Key Phase
bit being rejected.</t> bit being rejected.</t>
<t>The process of creating new packet protection keys for receiving pack ets could <t>The process of creating new packet protection keys for receiving pack ets could
reveal that a key update has occurred. An endpoint MAY generate new keys as reveal that a key update has occurred. An endpoint <bcp14>MAY</bcp14> generate n ew keys as
part of packet processing, but this creates a timing signal that could be used part of packet processing, but this creates a timing signal that could be used
by an attacker to learn when key updates happen and thus leak the value of the by an attacker to learn when key updates happen and thus leak the value of the
Key Phase bit.</t> Key Phase bit.</t>
<t>Endpoints are generally expected to have current and next receive pac ket <t>Endpoints are generally expected to have current and next receive pac ket
protection keys available. For a short period after a key update completes, up protection keys available. For a short period after a key update completes, up
to the PTO, endpoints MAY defer generation of the next set of to the PTO, endpoints <bcp14>MAY</bcp14> defer generation of the next set of
receive packet protection keys. This allows endpoints receive packet protection keys. This allows endpoints
to retain only two sets of receive keys; see <xref target="old-keys-recv" format ="default"/>.</t> to retain only two sets of receive keys; see <xref target="old-keys-recv" format ="default"/>.</t>
<t>Once generated, the next set of packet protection keys SHOULD be reta ined, even <t>Once generated, the next set of packet protection keys <bcp14>SHOULD< /bcp14> be retained, even
if the packet that was received was subsequently discarded. Packets containing if the packet that was received was subsequently discarded. Packets containing
apparent key updates are easy to forge and - while the process of key update apparent key updates are easy to forge, and while the process of key update does
does not require significant effort - triggering this process could be used by not require significant effort, triggering this process could be used by an
an attacker for DoS.</t> attacker for DoS.</t>
<t>For this reason, endpoints MUST be able to retain two sets of packet <t>For this reason, endpoints <bcp14>MUST</bcp14> be able to retain two
protection sets of packet protection
keys for receiving packets: the current and the next. Retaining the previous keys for receiving packets: the current and the next. Retaining the previous
keys in addition to these might improve performance, but this is not essential.< /t> keys in addition to these might improve performance, but this is not essential.< /t>
</section> </section>
<section anchor="old-keys-send" numbered="true" toc="default"> <section anchor="old-keys-send" numbered="true" toc="default">
<name>Sending with Updated Keys</name> <name>Sending with Updated Keys</name>
<t>An endpoint never sends packets that are protected with old keys. On ly the <t>An endpoint never sends packets that are protected with old keys. On ly the
current keys are used. Keys used for protecting packets can be discarded current keys are used. Keys used for protecting packets can be discarded
immediately after switching to newer keys.</t> immediately after switching to newer keys.</t>
<t>Packets with higher packet numbers MUST be protected with either the same or <t>Packets with higher packet numbers <bcp14>MUST</bcp14> be protected w ith either the same or
newer packet protection keys than packets with lower packet numbers. An newer packet protection keys than packets with lower packet numbers. An
endpoint that successfully removes protection with old keys when newer keys were endpoint that successfully removes protection with old keys when newer keys were
used for packets with lower packet numbers MUST treat this as a connection error used for packets with lower packet numbers <bcp14>MUST</bcp14> treat this as a c onnection error
of type KEY_UPDATE_ERROR.</t> of type KEY_UPDATE_ERROR.</t>
</section> </section>
<section anchor="old-keys-recv" numbered="true" toc="default"> <section anchor="old-keys-recv" numbered="true" toc="default">
<name>Receiving with Different Keys</name> <name>Receiving with Different Keys</name>
<t>For receiving packets during a key update, packets protected with old er keys <t>For receiving packets during a key update, packets protected with old er keys
might arrive if they were delayed by the network. Retaining old packet might arrive if they were delayed by the network. Retaining old packet
protection keys allows these packets to be successfully processed.</t> protection keys allows these packets to be successfully processed.</t>
<t>As packets protected with keys from the next key phase use the same K ey Phase <t>As packets protected with keys from the next key phase use the same K ey Phase
value as those protected with keys from the previous key phase, it is necessary value as those protected with keys from the previous key phase, it is necessary
to distinguish between the two, if packets protected with old keys are to be to distinguish between the two if packets protected with old keys are to be
processed. This can be done using packet numbers. A recovered packet number processed. This can be done using packet numbers. A recovered packet number
that is lower than any packet number from the current key phase uses the that is lower than any packet number from the current key phase uses the
previous packet protection keys; a recovered packet number that is higher than previous packet protection keys; a recovered packet number that is higher than
any packet number from the current key phase requires the use of the next packet any packet number from the current key phase requires the use of the next packet
protection keys.</t> protection keys.</t>
<t>Some care is necessary to ensure that any process for selecting betwe en <t>Some care is necessary to ensure that any process for selecting betwe en
previous, current, and next packet protection keys does not expose a timing side previous, current, and next packet protection keys does not expose a timing side
channel that might reveal which keys were used to remove packet protection. See channel that might reveal which keys were used to remove packet protection. See
<xref target="hp-side-channel" format="default"/> for more information.</t> <xref target="hp-side-channel" format="default"/> for more information.</t>
<t>Alternatively, endpoints can retain only two sets of packet protectio n keys, <t>Alternatively, endpoints can retain only two sets of packet protectio n keys,
swapping previous for next after enough time has passed to allow for reordering swapping previous for next after enough time has passed to allow for reordering
in the network. In this case, the Key Phase bit alone can be used to select in the network. In this case, the Key Phase bit alone can be used to select
keys.</t> keys.</t>
<t>An endpoint MAY allow a period of approximately the Probe Timeout (PT O; see <t>An endpoint <bcp14>MAY</bcp14> allow a period of approximately the Pr obe Timeout (PTO; see
<xref target="QUIC-RECOVERY" format="default"/>) after promoting the next set of receive keys to be current <xref target="QUIC-RECOVERY" format="default"/>) after promoting the next set of receive keys to be current
before it creates the subsequent set of packet protection keys. These updated before it creates the subsequent set of packet protection keys. These updated
keys MAY replace the previous keys at that time. With the caveat that PTO is a keys <bcp14>MAY</bcp14> replace the previous keys at that time. With the caveat
subjective measure - that is, a peer could have a different view of the RTT - that PTO is a
subjective measure -- that is, a peer could have a different view of the RTT --
this time is expected to be long enough that any reordered packets would be this time is expected to be long enough that any reordered packets would be
declared lost by a peer even if they were acknowledged and short enough to declared lost by a peer even if they were acknowledged and short enough to allow
allow a peer to initiate further key updates.</t> a peer to initiate further key updates.</t>
<t>Endpoints need to allow for the possibility that a peer might not be able to <t>Endpoints need to allow for the possibility that a peer might not be able to
decrypt packets that initiate a key update during the period when the peer decrypt packets that initiate a key update during the period when the peer
retains old keys. Endpoints SHOULD wait three times the PTO before initiating a retains old keys. Endpoints <bcp14>SHOULD</bcp14> wait three times the PTO befo re initiating a
key update after receiving an acknowledgment that confirms that the previous key key update after receiving an acknowledgment that confirms that the previous key
update was received. Failing to allow sufficient time could lead to packets update was received. Failing to allow sufficient time could lead to packets
being discarded.</t> being discarded.</t>
<t>An endpoint SHOULD retain old read keys for no more than three times the PTO <t>An endpoint <bcp14>SHOULD</bcp14> retain old read keys for no more th an three times the PTO
after having received a packet protected using the new keys. After this period, after having received a packet protected using the new keys. After this period,
old read keys and their corresponding secrets SHOULD be discarded.</t> old read keys and their corresponding secrets <bcp14>SHOULD</bcp14> be discarded .</t>
</section> </section>
<section anchor="aead-limits" numbered="true" toc="default"> <section anchor="aead-limits" numbered="true" toc="default">
<name>Limits on AEAD Usage</name> <name>Limits on AEAD Usage</name>
<t>This document sets usage limits for AEAD algorithms to ensure that ov eruse does <t>This document sets usage limits for AEAD algorithms to ensure that ov eruse does
not give an adversary a disproportionate advantage in attacking the not give an adversary a disproportionate advantage in attacking the
confidentiality and integrity of communications when using QUIC.</t> confidentiality and integrity of communications when using QUIC.</t>
<t>The usage limits defined in TLS 1.3 exist for protection against atta cks <t>The usage limits defined in TLS 1.3 exist for protection against atta cks
on confidentiality and apply to successful applications of AEAD protection. The on confidentiality and apply to successful applications of AEAD protection. The
integrity protections in authenticated encryption also depend on limiting the integrity protections in authenticated encryption also depend on limiting the
number of attempts to forge packets. TLS achieves this by closing connections number of attempts to forge packets. TLS achieves this by closing connections
after any record fails an authentication check. In comparison, QUIC ignores any after any record fails an authentication check. In comparison, QUIC ignores any
packet that cannot be authenticated, allowing multiple forgery attempts.</t> packet that cannot be authenticated, allowing multiple forgery attempts.</t>
<t>QUIC accounts for AEAD confidentiality and integrity limits separatel y. The <t>QUIC accounts for AEAD confidentiality and integrity limits separatel y. The
confidentiality limit applies to the number of packets encrypted with a given confidentiality limit applies to the number of packets encrypted with a given
key. The integrity limit applies to the number of packets decrypted within a key. The integrity limit applies to the number of packets decrypted within a
given connection. Details on enforcing these limits for each AEAD algorithm given connection. Details on enforcing these limits for each AEAD algorithm
follow below.</t> follow below.</t>
<t>Endpoints MUST count the number of encrypted packets for each set of keys. If <t>Endpoints <bcp14>MUST</bcp14> count the number of encrypted packets f or each set of keys. If
the total number of encrypted packets with the same key exceeds the the total number of encrypted packets with the same key exceeds the
confidentiality limit for the selected AEAD, the endpoint MUST stop using those confidentiality limit for the selected AEAD, the endpoint <bcp14>MUST</bcp14> st
keys. Endpoints MUST initiate a key update before sending more protected packets op using those
keys. Endpoints <bcp14>MUST</bcp14> initiate a key update before sending more pr
otected packets
than the confidentiality limit for the selected AEAD permits. If a key update than the confidentiality limit for the selected AEAD permits. If a key update
is not possible or integrity limits are reached, the endpoint MUST stop using is not possible or integrity limits are reached, the endpoint <bcp14>MUST</bcp14 > stop using
the connection and only send stateless resets in response to receiving packets. the connection and only send stateless resets in response to receiving packets.
It is RECOMMENDED that endpoints immediately close the connection with a It is <bcp14>RECOMMENDED</bcp14> that endpoints immediately close the connection with a
connection error of type AEAD_LIMIT_REACHED before reaching a state where key connection error of type AEAD_LIMIT_REACHED before reaching a state where key
updates are not possible.</t> updates are not possible.</t>
<t>For AEAD_AES_128_GCM and AEAD_AES_256_GCM, the confidentiality limit <t>For AEAD_AES_128_GCM and AEAD_AES_256_GCM, the confidentiality limit
is 2^23 is
encrypted packets; see <xref target="gcm-bounds" format="default"/>. For AEAD_CH 2<sup>23</sup> encrypted packets; see <xref target="gcm-bounds" format="default"
ACHA20_POLY1305, the />. For
confidentiality limit is greater than the number of possible packets (2^62) and AEAD_CHACHA20_POLY1305, the confidentiality limit is greater than the number of
so can be disregarded. For AEAD_AES_128_CCM, the confidentiality limit is 2^21.5 possible packets (2<sup>62</sup>) and so can be disregarded. For
encrypted packets; see <xref target="ccm-bounds" format="default"/>. Applying a AEAD_AES_128_CCM, the confidentiality limit is 2<sup>21.5</sup> encrypted
limit reduces the probability packets; see <xref target="ccm-bounds" format="default"/>. Applying a limit redu
that an attacker can distinguish the AEAD in use from a random permutation; see ces the probability that an
attacker can distinguish the AEAD in use from a random permutation; see
<xref target="AEBounds" format="default"/>, <xref target="ROBUST" format="defaul t"/>, and <xref target="GCM-MU" format="default"/>.</t> <xref target="AEBounds" format="default"/>, <xref target="ROBUST" format="defaul t"/>, and <xref target="GCM-MU" format="default"/>.</t>
<t>In addition to counting packets sent, endpoints MUST count the number of <t>In addition to counting packets sent, endpoints <bcp14>MUST</bcp14> c ount the number of
received packets that fail authentication during the lifetime of a connection. received packets that fail authentication during the lifetime of a connection.
If the total number of received packets that fail authentication within the If the total number of received packets that fail authentication within the
connection, across all keys, exceeds the integrity limit for the selected AEAD, connection, across all keys, exceeds the integrity limit for the selected AEAD,
the endpoint MUST immediately close the connection with a connection error of the endpoint <bcp14>MUST</bcp14> immediately close the connection with a connect ion error of
type AEAD_LIMIT_REACHED and not process any more packets.</t> type AEAD_LIMIT_REACHED and not process any more packets.</t>
<t>For AEAD_AES_128_GCM and AEAD_AES_256_GCM, the integrity limit is 2^5 <t>For AEAD_AES_128_GCM and AEAD_AES_256_GCM, the integrity limit is 2<s
2 invalid up>52</sup>
packets; see <xref target="gcm-bounds" format="default"/>. For AEAD_CHACHA20_POL invalid packets; see <xref target="gcm-bounds" format="default"/>. For AEAD_CHAC
Y1305, the integrity limit is HA20_POLY1305, the integrity
2^36 invalid packets; see <xref target="AEBounds" format="default"/>. For AEAD_A limit is 2<sup>36</sup> invalid packets; see <xref target="AEBounds" format="def
ES_128_CCM, the integrity ault"/>. For AEAD_AES_128_CCM,
limit is 2^21.5 invalid packets; see <xref target="ccm-bounds" format="default"/ the integrity limit is 2<sup>21.5</sup> invalid packets; see
>. Applying this limit reduces <xref target="ccm-bounds" format="default"/>. Applying this limit reduces the pr
the probability that an attacker can successfully forge a packet; see obability that an attacker can
<xref target="AEBounds" format="default"/>, <xref target="ROBUST" format="defaul successfully forge a packet; see <xref target="AEBounds" format="default"/>, <xr
t"/>, and <xref target="GCM-MU" format="default"/>.</t> ef target="ROBUST" format="default"/>, and <xref target="GCM-MU" format="default
<t>Endpoints that limit the size of packets MAY use higher confidentiali "/>.</t>
ty and <t>Endpoints that limit the size of packets <bcp14>MAY</bcp14> use highe
r confidentiality and
integrity limits; see <xref target="aead-analysis" format="default"/> for detail s.</t> integrity limits; see <xref target="aead-analysis" format="default"/> for detail s.</t>
<t>Future analyses and specifications MAY relax confidentiality or integ rity limits <t>Future analyses and specifications <bcp14>MAY</bcp14> relax confident iality or integrity limits
for an AEAD.</t> for an AEAD.</t>
<t>Any TLS cipher suite that is specified for use with QUIC MUST define limits on <t>Any TLS cipher suite that is specified for use with QUIC <bcp14>MUST< /bcp14> define limits on
the use of the associated AEAD function that preserves margins for the use of the associated AEAD function that preserves margins for
confidentiality and integrity. That is, limits MUST be specified for the number confidentiality and integrity. That is, limits <bcp14>MUST</bcp14> be specified for the number
of packets that can be authenticated and for the number of packets that can fail of packets that can be authenticated and for the number of packets that can fail
authentication. Providing a reference to any analysis upon which values are authentication. Providing a reference to any analysis upon which values are
based - and any assumptions used in that analysis - allows limits to be adapted based -- and any assumptions used in that analysis -- allows limits to be
to varying usage conditions.</t> adapted to varying usage conditions.</t>
</section> </section>
<section anchor="key-update-error" numbered="true" toc="default"> <section anchor="key-update-error" numbered="true" toc="default">
<name>Key Update Error Code</name> <name>Key Update Error Code</name>
<t>The KEY_UPDATE_ERROR error code (0xe) is used to signal errors relate d to key <t>The KEY_UPDATE_ERROR error code (0x0e) is used to signal errors relat ed to key
updates.</t> updates.</t>
</section> </section>
</section> </section>
<section anchor="security-of-initial-messages" numbered="true" toc="default" > <section anchor="security-of-initial-messages" numbered="true" toc="default" >
<name>Security of Initial Messages</name> <name>Security of Initial Messages</name>
<t>Initial packets are not protected with a secret key, so they are subjec t to <t>Initial packets are not protected with a secret key, so they are subjec t to
potential tampering by an attacker. QUIC provides protection against attackers potential tampering by an attacker. QUIC provides protection against attackers
that cannot read packets, but does not attempt to provide additional protection that cannot read packets but does not attempt to provide additional protection
against attacks where the attacker can observe and inject packets. Some forms against attacks where the attacker can observe and inject packets. Some forms
of tampering -- such as modifying the TLS messages themselves -- are detectable, of tampering -- such as modifying the TLS messages themselves -- are detectable,
but some -- such as modifying ACKs -- are not.</t> but some -- such as modifying ACKs -- are not.</t>
<t>For example, an attacker could inject a packet containing an ACK frame <t>For example, an attacker could inject a packet containing an ACK frame
that to
makes it appear that a packet had not been received or to create a false make it appear that a packet had not been received or to create a false
impression of the state of the connection (e.g., by modifying the ACK Delay). impression of the state of the connection (e.g., by modifying the ACK Delay).
Note that such a packet could cause a legitimate packet to be dropped as a Note that such a packet could cause a legitimate packet to be dropped as a
duplicate. Implementations SHOULD use caution in relying on any data that is duplicate. Implementations <bcp14>SHOULD</bcp14> use caution in relying on any data that is
contained in Initial packets that is not otherwise authenticated.</t> contained in Initial packets that is not otherwise authenticated.</t>
<t>It is also possible for the attacker to tamper with data that is carrie d in <t>It is also possible for the attacker to tamper with data that is carrie d in
Handshake packets, but because that tampering requires modifying TLS handshake Handshake packets, but because that sort of tampering requires modifying TLS
messages, that tampering will cause the TLS handshake to fail.</t> handshake messages, any such tampering will cause the TLS handshake to fail.</t>
</section> </section>
<section anchor="quic-specific-adjustments-to-the-tls-handshake" numbered="t rue" toc="default"> <section anchor="quic-specific-adjustments-to-the-tls-handshake" numbered="t rue" toc="default">
<name>QUIC-Specific Adjustments to the TLS Handshake</name> <name>QUIC-Specific Adjustments to the TLS Handshake</name>
<t>Certain aspects of the TLS handshake are different when used with QUIC. </t> <t>Certain aspects of the TLS handshake are different when used with QUIC. </t>
<t>QUIC also requires additional features from TLS. In addition to negoti ation of <t>QUIC also requires additional features from TLS. In addition to negoti ation of
cryptographic parameters, the TLS handshake carries and authenticates values for cryptographic parameters, the TLS handshake carries and authenticates values for
QUIC transport parameters.</t> QUIC transport parameters.</t>
<section anchor="protocol-negotiation" numbered="true" toc="default"> <section anchor="protocol-negotiation" numbered="true" toc="default">
<name>Protocol Negotiation</name> <name>Protocol Negotiation</name>
<t>QUIC requires that the cryptographic handshake provide authenticated protocol <t>QUIC requires that the cryptographic handshake provide authenticated protocol
negotiation. TLS uses Application Layer Protocol Negotiation negotiation. TLS uses Application-Layer Protocol Negotiation
(<xref target="ALPN" format="default"/>) to select an application protocol. Unl <xref target="ALPN" format="default"/> to select an application protocol. Unles
ess another mechanism s another mechanism
is used for agreeing on an application protocol, endpoints MUST use ALPN for is used for agreeing on an application protocol, endpoints <bcp14>MUST</bcp14> u
se ALPN for
this purpose.</t> this purpose.</t>
<t>When using ALPN, endpoints MUST immediately close a connection (see S <t>When using ALPN, endpoints <bcp14>MUST</bcp14> immediately close a co
ection nnection (see <xref section="10.2" sectionFormat="of" target="QUIC-TRANSPORT" fo
10.2 of <xref target="QUIC-TRANSPORT" format="default"/>) with a no_application_ rmat="default"/>) with a no_application_protocol TLS alert (QUIC error
protocol TLS alert (QUIC error code 0x0178; see <xref target="tls-errors" format="default"/>) if an application
code 0x178; see <xref target="tls-errors" format="default"/>) if an application protocol is not negotiated.
protocol is not negotiated. While <xref target="ALPN" format="default"/> only specifies that servers use thi
While <xref target="ALPN" format="default"/> only specifies that servers use thi s alert, QUIC clients <bcp14>MUST</bcp14>
s alert, QUIC clients MUST use error 0x0178 to terminate a connection when ALPN negotiation fails.</t>
use error 0x178 to terminate a connection when ALPN negotiation fails.</t> <t>An application protocol <bcp14>MAY</bcp14> restrict the QUIC versions
<t>An application protocol MAY restrict the QUIC versions that it can op that it can operate over.
erate over. Servers <bcp14>MUST</bcp14> select an application protocol compatible with the Q
Servers MUST select an application protocol compatible with the QUIC version UIC version
that the client has selected. The server MUST treat the inability to select a that the client has selected. The server <bcp14>MUST</bcp14> treat the inabilit
compatible application protocol as a connection error of type 0x178 y to select a
(no_application_protocol). Similarly, a client MUST treat the selection of an compatible application protocol as a connection error of type 0x0178
(no_application_protocol). Similarly, a client <bcp14>MUST</bcp14> treat the se
lection of an
incompatible application protocol by a server as a connection error of type incompatible application protocol by a server as a connection error of type
0x178.</t> 0x0178.</t>
</section> </section>
<section anchor="quic_parameters" numbered="true" toc="default"> <section anchor="quic_parameters" numbered="true" toc="default">
<name>QUIC Transport Parameters Extension</name> <name>QUIC Transport Parameters Extension</name>
<t>QUIC transport parameters are carried in a TLS extension. Different v ersions of <t>QUIC transport parameters are carried in a TLS extension. Different v ersions of
QUIC might define a different method for negotiating transport configuration.</t > QUIC might define a different method for negotiating transport configuration.</t >
<t>Including transport parameters in the TLS handshake provides integrit y <t>Including transport parameters in the TLS handshake provides integrit y
protection for these values.</t> protection for these values.</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="tls-presentation"><![CDATA[
enum { enum {
quic_transport_parameters(0x39), (65535) quic_transport_parameters(0x39), (65535)
} ExtensionType; } ExtensionType;
]]></artwork> ]]></sourcecode>
<t>The extension_data field of the quic_transport_parameters extension c ontains a <t>The extension_data field of the quic_transport_parameters extension c ontains a
value that is defined by the version of QUIC that is in use.</t> value that is defined by the version of QUIC that is in use.</t>
<t>The quic_transport_parameters extension is carried in the ClientHello and the <t>The quic_transport_parameters extension is carried in the ClientHello and the
EncryptedExtensions messages during the handshake. Endpoints MUST send the EncryptedExtensions messages during the handshake. Endpoints <bcp14>MUST</bcp14> send the
quic_transport_parameters extension; endpoints that receive ClientHello or quic_transport_parameters extension; endpoints that receive ClientHello or
EncryptedExtensions messages without the quic_transport_parameters extension EncryptedExtensions messages without the quic_transport_parameters extension
MUST close the connection with an error of type 0x16d (equivalent to a fatal TLS <bcp14>MUST</bcp14> close the connection with an error of type 0x016d (equivalen
missing_extension alert, see <xref target="tls-errors" format="default"/>).</t> t to a fatal
TLS missing_extension alert, see <xref target="tls-errors" format="default"/>).<
/t>
<t>Transport parameters become available prior to the completion of the handshake. <t>Transport parameters become available prior to the completion of the handshake.
A server might use these values earlier than handshake completion. However, the A server might use these values earlier than handshake completion. However, the
value of transport parameters is not authenticated until the handshake value of transport parameters is not authenticated until the handshake
completes, so any use of these parameters cannot depend on their authenticity. completes, so any use of these parameters cannot depend on their authenticity.
Any tampering with transport parameters will cause the handshake to fail.</t> Any tampering with transport parameters will cause the handshake to fail.</t>
<t>Endpoints MUST NOT send this extension in a TLS connection that does not use <t>Endpoints <bcp14>MUST NOT</bcp14> send this extension in a TLS connec tion that does not use
QUIC (such as the use of TLS with TCP defined in <xref target="TLS13" format="de fault"/>). A fatal QUIC (such as the use of TLS with TCP defined in <xref target="TLS13" format="de fault"/>). A fatal
unsupported_extension alert MUST be sent by an implementation that supports this unsupported_extension alert <bcp14>MUST</bcp14> be sent by an implementation tha t supports this
extension if the extension is received when the transport is not QUIC.</t> extension if the extension is received when the transport is not QUIC.</t>
<t>Negotiating the quic_transport_parameters extension causes the EndOfE arlyData to <t>Negotiating the quic_transport_parameters extension causes the EndOfE arlyData to
be removed; see <xref target="remove-eoed" format="default"/>.</t> be removed; see <xref target="remove-eoed" format="default"/>.</t>
</section> </section>
<section anchor="remove-eoed" numbered="true" toc="default"> <section anchor="remove-eoed" numbered="true" toc="default">
<name>Removing the EndOfEarlyData Message</name> <name>Removing the EndOfEarlyData Message</name>
<t>The TLS EndOfEarlyData message is not used with QUIC. QUIC does not rely on <t>The TLS EndOfEarlyData message is not used with QUIC. QUIC does not rely on
this message to mark the end of 0-RTT data or to signal the change to Handshake this message to mark the end of 0-RTT data or to signal the change to Handshake
keys.</t> keys.</t>
<t>Clients MUST NOT send the EndOfEarlyData message. A server MUST trea t receipt <t>Clients <bcp14>MUST NOT</bcp14> send the EndOfEarlyData message. A s erver <bcp14>MUST</bcp14> treat receipt
of a CRYPTO frame in a 0-RTT packet as a connection error of type of a CRYPTO frame in a 0-RTT packet as a connection error of type
PROTOCOL_VIOLATION.</t> PROTOCOL_VIOLATION.</t>
<t>As a result, EndOfEarlyData does not appear in the TLS handshake tran script.</t> <t>As a result, EndOfEarlyData does not appear in the TLS handshake tran script.</t>
</section> </section>
<section anchor="compat-mode" numbered="true" toc="default"> <section anchor="compat-mode" numbered="true" toc="default">
<name>Prohibit TLS Middlebox Compatibility Mode</name> <name>Prohibit TLS Middlebox Compatibility Mode</name>
<t>Appendix D.4 of <xref target="TLS13" format="default"/> describes an alteration to the TLS 1.3 handshake as <t>Appendix D.4 of <xref target="TLS13" format="default"/> describes an alteration to the TLS 1.3 handshake as
a workaround for bugs in some middleboxes. The TLS 1.3 middlebox compatibility a workaround for bugs in some middleboxes. The TLS 1.3 middlebox compatibility
mode involves setting the legacy_session_id field to a 32-byte value in the mode involves setting the legacy_session_id field to a 32-byte value in the
ClientHello and ServerHello, then sending a change_cipher_spec record. Both ClientHello and ServerHello, then sending a change_cipher_spec record. Both
field and record carry no semantic content and are ignored.</t> field and record carry no semantic content and are ignored.</t>
<t>This mode has no use in QUIC as it only applies to middleboxes that i nterfere <t>This mode has no use in QUIC as it only applies to middleboxes that i nterfere
with TLS over TCP. QUIC also provides no means to carry a change_cipher_spec with TLS over TCP. QUIC also provides no means to carry a change_cipher_spec
record. A client MUST NOT request the use of the TLS 1.3 compatibility mode. A record. A client <bcp14>MUST NOT</bcp14> request the use of the TLS 1.3 compatib
server SHOULD treat the receipt of a TLS ClientHello with a non-empty ility mode. A
server <bcp14>SHOULD</bcp14> treat the receipt of a TLS ClientHello with a non-e
mpty
legacy_session_id field as a connection error of type PROTOCOL_VIOLATION.</t> legacy_session_id field as a connection error of type PROTOCOL_VIOLATION.</t>
</section> </section>
</section> </section>
<section anchor="security-considerations" numbered="true" toc="default"> <section anchor="security-considerations" numbered="true" toc="default">
<name>Security Considerations</name> <name>Security Considerations</name>
<t>All of the security considerations that apply to TLS also apply to the use of <t>All of the security considerations that apply to TLS also apply to the use of
TLS in QUIC. Reading all of <xref target="TLS13" format="default"/> and its appe ndices is the best way to TLS in QUIC. Reading all of <xref target="TLS13" format="default"/> and its appe ndices is the best way to
gain an understanding of the security properties of QUIC.</t> gain an understanding of the security properties of QUIC.</t>
<t>This section summarizes some of the more important security aspects spe cific to <t>This section summarizes some of the more important security aspects spe cific to
the TLS integration, though there are many security-relevant details in the the TLS integration, though there are many security-relevant details in the
remainder of the document.</t> remainder of the document.</t>
<section anchor="session-linkability" numbered="true" toc="default"> <section anchor="session-linkability" numbered="true" toc="default">
<name>Session Linkability</name> <name>Session Linkability</name>
<t>Use of TLS session tickets allows servers and possibly other entities to <t>Use of TLS session tickets allows servers and possibly other entities to
correlate connections made by the same client; see <xref target="resumption" for mat="default"/> for details.</t> correlate connections made by the same client; see <xref target="resumption" for mat="default"/> for details.</t>
</section> </section>
<section anchor="replay" numbered="true" toc="default"> <section anchor="replay" numbered="true" toc="default">
<name>Replay Attacks with 0-RTT</name> <name>Replay Attacks with 0-RTT</name>
<t>As described in Section 8 of <xref target="TLS13" format="default"/>, use of TLS early data comes with an <t>As described in <xref section="8" sectionFormat="of" target="TLS13" f ormat="default"/>, use of TLS early data comes with an
exposure to replay attack. The use of 0-RTT in QUIC is similarly vulnerable to exposure to replay attack. The use of 0-RTT in QUIC is similarly vulnerable to
replay attack.</t> replay attack.</t>
<t>Endpoints MUST implement and use the replay protections described in <xref target="TLS13" format="default"/>, <t>Endpoints <bcp14>MUST</bcp14> implement and use the replay protection s described in <xref target="TLS13" format="default"/>,
however it is recognized that these protections are imperfect. Therefore, however it is recognized that these protections are imperfect. Therefore,
additional consideration of the risk of replay is needed.</t> additional consideration of the risk of replay is needed.</t>
<t>QUIC is not vulnerable to replay attack, except via the application p rotocol <t>QUIC is not vulnerable to replay attack, except via the application p rotocol
information it might carry. The management of QUIC protocol state based on the information it might carry. The management of QUIC protocol state based on the
frame types defined in <xref target="QUIC-TRANSPORT" format="default"/> is not v ulnerable to replay. frame types defined in <xref target="QUIC-TRANSPORT" format="default"/> is not v ulnerable to replay.
Processing of QUIC frames is idempotent and cannot result in invalid connection Processing of QUIC frames is idempotent and cannot result in invalid connection
states if frames are replayed, reordered or lost. QUIC connections do not states if frames are replayed, reordered, or lost. QUIC connections do not
produce effects that last beyond the lifetime of the connection, except for produce effects that last beyond the lifetime of the connection, except for
those produced by the application protocol that QUIC serves.</t> those produced by the application protocol that QUIC serves.</t>
<dl> <t>TLS session tickets and address validation tokens are used to carry Q
<dt> UIC
Note: </dt> configuration information between connections, specifically, to enable a server
<dd> to efficiently recover state that is used in connection establishment and
<t>TLS session tickets and address validation tokens are used to car address validation. These <bcp14>MUST NOT</bcp14> be used to communicate applic
ry QUIC ation semantics
configuration information between connections. Specifically, to enable a between endpoints; clients <bcp14>MUST</bcp14> treat them as opaque values. The
server to efficiently recover state that is used in connection establishment potential for
and address validation. These MUST NOT be used to communicate application reuse of these tokens means that they require stronger protections against
semantics between endpoints; clients MUST treat them as opaque values. The replay.</t>
potential for reuse of these tokens means that they require stronger
protections against replay.</t>
</dd>
</dl>
<t>A server that accepts 0-RTT on a connection incurs a higher cost than accepting <t>A server that accepts 0-RTT on a connection incurs a higher cost than accepting
a connection without 0-RTT. This includes higher processing and computation a connection without 0-RTT. This includes higher processing and computation
costs. Servers need to consider the probability of replay and all associated costs. Servers need to consider the probability of replay and all associated
costs when accepting 0-RTT.</t> costs when accepting 0-RTT.</t>
<t>Ultimately, the responsibility for managing the risks of replay attac ks with <t>Ultimately, the responsibility for managing the risks of replay attac ks with
0-RTT lies with an application protocol. An application protocol that uses QUIC 0-RTT lies with an application protocol. An application protocol that uses QUIC
MUST describe how the protocol uses 0-RTT and the measures that are employed to <bcp14>MUST</bcp14> describe how the protocol uses 0-RTT and the measures that a re employed to
protect against replay attack. An analysis of replay risk needs to consider protect against replay attack. An analysis of replay risk needs to consider
all QUIC protocol features that carry application semantics.</t> all QUIC protocol features that carry application semantics.</t>
<t>Disabling 0-RTT entirely is the most effective defense against replay attack.</t> <t>Disabling 0-RTT entirely is the most effective defense against replay attack.</t>
<t>QUIC extensions MUST describe how replay attacks affect their operati <t>QUIC extensions <bcp14>MUST</bcp14> either describe how replay attack
on, or s affect their operation
prohibit their use in 0-RTT. Application protocols MUST either prohibit the use or prohibit the use of the extension in 0-RTT. Application protocols <bcp14>MUS
of extensions that carry application semantics in 0-RTT or provide replay T</bcp14>
mitigation strategies.</t> either prohibit the use of extensions that carry application semantics in 0-RTT
or provide replay mitigation strategies.</t>
</section> </section>
<section anchor="reflection" numbered="true" toc="default"> <section anchor="reflection" numbered="true" toc="default">
<name>Packet Reflection Attack Mitigation</name> <name>Packet Reflection Attack Mitigation</name>
<t>A small ClientHello that results in a large block of handshake messag es from a <t>A small ClientHello that results in a large block of handshake messag es from a
server can be used in packet reflection attacks to amplify the traffic generated server can be used in packet reflection attacks to amplify the traffic generated
by an attacker.</t> by an attacker.</t>
<t>QUIC includes three defenses against this attack. First, the packet c <t>QUIC includes three defenses against this attack. First, the packet c
ontaining a ontaining
ClientHello MUST be padded to a minimum size. Second, if responding to an a ClientHello <bcp14>MUST</bcp14> be padded to a minimum size. Second, if respon
unverified source address, the server is forbidden to send more than three times ding to an
as many bytes as the number of bytes it has received (see Section 8.1 of unverified source address, the server is forbidden to send more than three
<xref target="QUIC-TRANSPORT" format="default"/>). Finally, because acknowledgme times as many bytes as the number of bytes it has received (see <xref section="8
nts of Handshake packets are .1" sectionFormat="of" target="QUIC-TRANSPORT" format="default"/>). Finally, bec
authenticated, a blind attacker cannot forge them. Put together, these defenses ause acknowledgments of Handshake packets are
authenticated, a blind attacker cannot forge them. Put together, these defenses
limit the level of amplification.</t> limit the level of amplification.</t>
</section> </section>
<section anchor="header-protect-analysis" numbered="true" toc="default"> <section anchor="header-protect-analysis" numbered="true" toc="default">
<name>Header Protection Analysis</name> <name>Header Protection Analysis</name>
<t><xref target="NAN" format="default"/> analyzes authenticated encrypti on <t><xref target="NAN" format="default"/> analyzes authenticated encrypti on
algorithms that provide nonce privacy, referred to as "Hide Nonce" (HN) algorithms that provide nonce privacy, referred to as "Hide Nonce" (HN)
transforms. The general header protection construction in this document is transforms. The general header protection construction in this document is
one of those algorithms (HN1). Header protection is applied after the packet one of those algorithms (HN1). Header protection is applied after the packet
protection AEAD, sampling a set of bytes (<tt>sample</tt>) from the AEAD output and protection AEAD, sampling a set of bytes (<tt>sample</tt>) from the AEAD output and
encrypting the header field using a pseudorandom function (PRF) as follows:</t> encrypting the header field using a pseudorandom function (PRF) as follows:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <sourcecode type="pseudocode"><![CDATA[
protected_field = field XOR PRF(hp_key, sample) protected_field = field XOR PRF(hp_key, sample)
]]></artwork> ]]></sourcecode>
<t>The header protection variants in this document use a pseudorandom pe rmutation <t>The header protection variants in this document use a pseudorandom pe rmutation
(PRP) in place of a generic PRF. However, since all PRPs are also PRFs <xref tar get="IMC" format="default"/>, (PRP) in place of a generic PRF. However, since all PRPs are also PRFs <xref tar get="IMC" format="default"/>,
these variants do not deviate from the HN1 construction.</t> these variants do not deviate from the HN1 construction.</t>
<t>As <tt>hp_key</tt> is distinct from the packet protection key, it fol lows that header <t>As <tt>hp_key</tt> is distinct from the packet protection key, it fol lows that header
protection achieves AE2 security as defined in <xref target="NAN" format="defaul t"/> and therefore guarantees protection achieves AE2 security as defined in <xref target="NAN" format="defaul t"/> and therefore guarantees
privacy of <tt>field</tt>, the protected packet header. Future header protection privacy of <tt>field</tt>, the protected packet header. Future header protection
variants based on this construction MUST use a PRF to ensure equivalent variants based on this construction <bcp14>MUST</bcp14> use a PRF to ensure equi valent
security guarantees.</t> security guarantees.</t>
<t>Use of the same key and ciphertext sample more than once risks compro mising <t>Use of the same key and ciphertext sample more than once risks compro mising
header protection. Protecting two different headers with the same key and header protection. Protecting two different headers with the same key and
ciphertext sample reveals the exclusive OR of the protected fields. Assuming ciphertext sample reveals the exclusive OR of the protected fields. Assuming
that the AEAD acts as a PRF, if L bits are sampled, the odds of two ciphertext that the AEAD acts as a PRF, if L bits are sampled, the odds of two ciphertext
samples being identical approach 2^(-L/2), that is, the birthday bound. For the samples being identical approach 2<sup>-L/2</sup>, that is, the birthday bound.
algorithms described in this document, that probability is one in 2^64.</t> For the algorithms described in this document, that probability is one in
2<sup>64</sup>.</t>
<t>To prevent an attacker from modifying packet headers, the header is t ransitively <t>To prevent an attacker from modifying packet headers, the header is t ransitively
authenticated using packet protection; the entire packet header is part of the authenticated using packet protection; the entire packet header is part of the
authenticated additional data. Protected fields that are falsified or modified authenticated additional data. Protected fields that are falsified or modified
can only be detected once the packet protection is removed.</t> can only be detected once the packet protection is removed.</t>
</section> </section>
<section anchor="hp-side-channel" numbered="true" toc="default"> <section anchor="hp-side-channel" numbered="true" toc="default">
<name>Header Protection Timing Side-Channels</name> <name>Header Protection Timing Side Channels</name>
<t>An attacker could guess values for packet numbers or Key Phase and ha ve an <t>An attacker could guess values for packet numbers or Key Phase and ha ve an
endpoint confirm guesses through timing side channels. Similarly, guesses for endpoint confirm guesses through timing side channels. Similarly, guesses for
the packet number length can be tried and exposed. If the recipient of a the packet number length can be tried and exposed. If the recipient of a packet
packet discards packets with duplicate packet numbers without attempting to discards packets with duplicate packet numbers without attempting to remove
remove packet protection they could reveal through timing side-channels that the packet protection, they could reveal through timing side channels that the
packet number matches a received packet. For authentication to be free from packet number matches a received packet. For authentication to be free from
side-channels, the entire process of header protection removal, packet number side channels, the entire process of header protection removal, packet number
recovery, and packet protection removal MUST be applied together without timing recovery, and packet protection removal <bcp14>MUST</bcp14> be applied together
and other side-channels.</t> without timing
and other side channels.</t>
<t>For the sending of packets, construction and protection of packet pay loads and <t>For the sending of packets, construction and protection of packet pay loads and
packet numbers MUST be free from side-channels that would reveal the packet packet numbers <bcp14>MUST</bcp14> be free from side channels that would reveal the packet
number or its encoded size.</t> number or its encoded size.</t>
<t>During a key update, the time taken to generate new keys could reveal through <t>During a key update, the time taken to generate new keys could reveal through
timing side-channels that a key update has occurred. Alternatively, where an timing side channels that a key update has occurred. Alternatively, where an
attacker injects packets this side-channel could reveal the value of the Key attacker injects packets, this side channel could reveal the value of the Key
Phase on injected packets. After receiving a key update, an endpoint SHOULD Phase on injected packets. After receiving a key update, an endpoint <bcp14>SHO
ULD</bcp14>
generate and save the next set of receive packet protection keys, as described generate and save the next set of receive packet protection keys, as described
in <xref target="receive-key-generation" format="default"/>. By generating new keys before a key update is in <xref target="receive-key-generation" format="default"/>. By generating new keys before a key update is
received, receipt of packets will not create timing signals that leak the value received, receipt of packets will not create timing signals that leak the value
of the Key Phase.</t> of the Key Phase.</t>
<t>This depends on not doing this key generation during packet processin g and it <t>This depends on not doing this key generation during packet processin g, and it
can require that endpoints maintain three sets of packet protection keys for can require that endpoints maintain three sets of packet protection keys for
receiving: for the previous key phase, for the current key phase, and for the receiving: for the previous key phase, for the current key phase, and for the
next key phase. Endpoints can instead choose to defer generation of the next next key phase. Endpoints can instead choose to defer generation of the next
receive packet protection keys until they discard old keys so that only two sets receive packet protection keys until they discard old keys so that only two sets
of receive keys need to be retained at any point in time.</t> of receive keys need to be retained at any point in time.</t>
</section> </section>
<section anchor="key-diversity" numbered="true" toc="default"> <section anchor="key-diversity" numbered="true" toc="default">
<name>Key Diversity</name> <name>Key Diversity</name>
<t>In using TLS, the central key schedule of TLS is used. As a result o f the TLS <t>In using TLS, the central key schedule of TLS is used. As a result o f the TLS
handshake messages being integrated into the calculation of secrets, the handshake messages being integrated into the calculation of secrets, the
inclusion of the QUIC transport parameters extension ensures that handshake and inclusion of the QUIC transport parameters extension ensures that the handshake
1-RTT keys are not the same as those that might be produced by a server running and 1-RTT keys are not the same as those that might be produced by a server
TLS over TCP. To avoid the possibility of cross-protocol key synchronization, running TLS over TCP. To avoid the possibility of cross-protocol key
additional measures are provided to improve key separation.</t> synchronization, additional measures are provided to improve key separation.</t>
<t>The QUIC packet protection keys and IVs are derived using a different label than <t>The QUIC packet protection keys and IVs are derived using a different label than
the equivalent keys in TLS.</t> the equivalent keys in TLS.</t>
<t>To preserve this separation, a new version of QUIC SHOULD define new labels for <t>To preserve this separation, a new version of QUIC <bcp14>SHOULD</bcp 14> define new labels for
key derivation for packet protection key and IV, plus the header protection key derivation for packet protection key and IV, plus the header protection
keys. This version of QUIC uses the string "quic". Other versions can use a keys. This version of QUIC uses the string "quic". Other versions can use a
version-specific label in place of that string.</t> version-specific label in place of that string.</t>
<t>The initial secrets use a key that is specific to the negotiated QUIC version. <t>The initial secrets use a key that is specific to the negotiated QUIC version.
New QUIC versions SHOULD define a new salt value used in calculating initial New QUIC versions <bcp14>SHOULD</bcp14> define a new salt value used in calculat ing initial
secrets.</t> secrets.</t>
</section> </section>
<section anchor="randomness" numbered="true" toc="default"> <section anchor="randomness" numbered="true" toc="default">
<name>Randomness</name> <name>Randomness</name>
<t>QUIC depends on endpoints being able to generate secure random number s, both <t>QUIC depends on endpoints being able to generate secure random number s, both
directly for protocol values such as the connection ID, and transitively via directly for protocol values such as the connection ID, and transitively via
TLS. See <xref target="RFC4086" format="default"/> for guidance on secure random number generation.</t> TLS. See <xref target="RFC4086" format="default"/> for guidance on secure random number generation.</t>
</section> </section>
</section> </section>
<section anchor="iana-considerations" numbered="true" toc="default"> <section anchor="iana-considerations" numbered="true" toc="default">
<name>IANA Considerations</name> <name>IANA Considerations</name>
<t>IANA has registered a codepoint of 57 (or 0x39) for the <t>IANA has registered a codepoint of 57 (or 0x39) for the
quic_transport_parameters extension (defined in <xref target="quic_parameters" f quic_transport_parameters extension (defined in <xref target="quic_parameters" f
ormat="default"/>) in the TLS ormat="default"/>) in the "TLS
ExtensionType Values Registry <xref target="TLS-REGISTRIES" format="default"/>.< ExtensionType Values" registry <xref target="TLS-REGISTRIES" format="default"/>.
/t> </t>
<t>The Recommended column for this extension is marked Yes. The TLS 1.3 Co lumn <t>The Recommended column for this extension is marked Yes. The TLS 1.3 Co lumn
includes CH and EE.</t> includes CH (ClientHello) and EE (EncryptedExtensions).</t>
<table anchor="iana-tls-ext" align="center">
<name>TLS ExtensionType Values Registry Entry</name>
<thead>
<tr>
<th align="right">Value</th>
<th align="left">Extension Name</th>
<th align="left">TLS 1.3</th>
<th align="left">Recommended</th>
<th align="left">Reference</th>
</tr>
</thead>
<tbody>
<tr>
<td align="right">57</td>
<td align="left">quic_transport_parameters</td>
<td align="left">CH, EE</td>
<td align="left">Y</td>
<td align="left">This document</td>
</tr>
</tbody>
</table>
</section> </section>
</middle> </middle>
<back> <back>
<references> <references>
<name>References</name> <name>References</name>
<references> <references>
<name>Normative References</name> <name>Normative References</name>
<reference anchor="QUIC-TRANSPORT"> <reference anchor="QUIC-TRANSPORT" target="https://www.rfc-editor.org/in fo/rfc9000">
<front> <front>
<title>QUIC: A UDP-Based Multiplexed and Secure Transport</title> <title>QUIC: A UDP-Based Multiplexed and Secure Transport</title>
<author initials="J." surname="Iyengar" fullname="Jana Iyengar" role ="editor"> <author initials="J." surname="Iyengar" fullname="Jana Iyengar" role ="editor">
<organization>Fastly</organization> <organization>Fastly</organization>
</author> </author>
<author initials="M." surname="Thomson" fullname="Martin Thomson" ro le="editor"> <author initials="M." surname="Thomson" fullname="Martin Thomson" ro le="editor">
<organization>Mozilla</organization> <organization>Mozilla</organization>
</author> </author>
<date year="2021" month="January" day="15"/> <date year="2021" month="May"/>
</front> </front>
<seriesInfo name="Internet-Draft" value="draft-ietf-quic-transport-34" <seriesInfo name="RFC" value="9000"/>
/> <seriesInfo name="DOI" value="10.17487/RFC9000"/>
</reference> </reference>
<reference anchor="QUIC-RECOVERY"> <reference anchor="QUIC-RECOVERY" target="https://www.rfc-editor.org/inf o/rfc9002">
<front> <front>
<title>QUIC Loss Detection and Congestion Control</title> <title>QUIC Loss Detection and Congestion Control</title>
<author initials="J." surname="Iyengar" fullname="Jana Iyengar" role ="editor"> <author initials="J." surname="Iyengar" fullname="Jana Iyengar" role ="editor">
<organization>Fastly</organization> <organization>Fastly</organization>
</author> </author>
<author initials="I." surname="Swett" fullname="Ian Swett" role="edi tor"> <author initials="I." surname="Swett" fullname="Ian Swett" role="edi tor">
<organization>Google</organization> <organization>Google</organization>
</author> </author>
<date year="2021" month="January" day="15"/> <date year="2021" month="May"/>
</front> </front>
<seriesInfo name="Internet-Draft" value="draft-ietf-quic-recovery-34"/ <seriesInfo name="RFC" value="9002"/>
> <seriesInfo name="DOI" value="10.17487/RFC9002"/>
</reference>
<reference anchor="HKDF" target="https://www.rfc-editor.org/info/rfc5869
">
<front>
<title>HMAC-based Extract-and-Expand Key Derivation Function (HKDF)<
/title>
<author fullname="H. Krawczyk" initials="H." surname="Krawczyk">
<organization/>
</author>
<author fullname="P. Eronen" initials="P." surname="Eronen">
<organization/>
</author>
<date month="May" year="2010"/>
<abstract>
<t>This document specifies a simple Hashed Message Authentication
Code (HMAC)-based key derivation function (HKDF), which can be used as a buildin
g block in various protocols and applications. The key derivation function (KDF
) is intended to support a wide range of applications and requirements, and is c
onservative in its use of cryptographic hash functions. This document is not an
Internet Standards Track specification; it is published for informational pur
poses.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5869"/>
<seriesInfo name="DOI" value="10.17487/RFC5869"/>
</reference> </reference>
<reference anchor="TLS13" target="https://www.rfc-editor.org/info/rfc844 6"> <reference anchor="TLS13" target="https://www.rfc-editor.org/info/rfc844 6">
<front> <front>
<title>The Transport Layer Security (TLS) Protocol Version 1.3</titl e> <title>The Transport Layer Security (TLS) Protocol Version 1.3</titl e>
<author initials="E." surname="Rescorla" fullname="E. Rescorla"> <author fullname="E. Rescorla" initials="E." surname="Rescorla">
<organization/> <organization/>
</author> </author>
<date year="2018" month="August"/> <date month="August" year="2018"/>
<abstract> <abstract>
<t>This document specifies version 1.3 of the Transport Layer Secu rity (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.</t> <t>This document specifies version 1.3 of the Transport Layer Secu rity (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.</t>
<t>This document updates RFCs 5705 and 6066, and obsoletes RFCs 50 77, 5246, and 6961. This document also specifies new requirements for TLS 1.2 i mplementations.</t> <t>This document updates RFCs 5705 and 6066, and obsoletes RFCs 50 77, 5246, and 6961. This document also specifies new requirements for TLS 1.2 i mplementations.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="8446"/> <seriesInfo name="RFC" value="8446"/>
<seriesInfo name="DOI" value="10.17487/RFC8446"/> <seriesInfo name="DOI" value="10.17487/RFC8446"/>
</reference> </reference>
<reference anchor="RFC2119" target="https://www.rfc-editor.org/info/rfc2 119"> <reference anchor="RFC2119" target="https://www.rfc-editor.org/info/rfc2 119">
<front> <front>
<title>Key words for use in RFCs to Indicate Requirement Levels</tit le> <title>Key words for use in RFCs to Indicate Requirement Levels</tit le>
<author initials="S." surname="Bradner" fullname="S. Bradner"> <author fullname="S. Bradner" initials="S." surname="Bradner">
<organization/> <organization/>
</author> </author>
<date year="1997" month="March"/> <date month="March" year="1997"/>
<abstract> <abstract>
<t>In many standards track documents several words are used to sig nify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF document s. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t> <t>In many standards track documents several words are used to sig nify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF document s. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="BCP" value="14"/> <seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="2119"/> <seriesInfo name="RFC" value="2119"/>
<seriesInfo name="DOI" value="10.17487/RFC2119"/> <seriesInfo name="DOI" value="10.17487/RFC2119"/>
</reference> </reference>
<reference anchor="RFC8174" target="https://www.rfc-editor.org/info/rfc8 174"> <reference anchor="RFC8174" target="https://www.rfc-editor.org/info/rfc8 174">
<front> <front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</ti tle> <title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</ti tle>
<author initials="B." surname="Leiba" fullname="B. Leiba"> <author fullname="B. Leiba" initials="B." surname="Leiba">
<organization/> <organization/>
</author> </author>
<date year="2017" month="May"/> <date month="May" year="2017"/>
<abstract> <abstract>
<t>RFC 2119 specifies common key words that may be used in protoco l specifications. This document aims to reduce the ambiguity by clarifying tha t only UPPERCASE usage of the key words have the defined special meanings.</t> <t>RFC 2119 specifies common key words that may be used in protoco l specifications. This document aims to reduce the ambiguity by clarifying tha t only UPPERCASE usage of the key words have the defined special meanings.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="BCP" value="14"/> <seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="8174"/> <seriesInfo name="RFC" value="8174"/>
<seriesInfo name="DOI" value="10.17487/RFC8174"/> <seriesInfo name="DOI" value="10.17487/RFC8174"/>
</reference> </reference>
<reference anchor="AEAD" target="https://www.rfc-editor.org/info/rfc5116 "> <reference anchor="AEAD" target="https://www.rfc-editor.org/info/rfc5116 ">
<front> <front>
<title>An Interface and Algorithms for Authenticated Encryption</tit le> <title>An Interface and Algorithms for Authenticated Encryption</tit le>
<author initials="D." surname="McGrew" fullname="D. McGrew"> <author fullname="D. McGrew" initials="D." surname="McGrew">
<organization/> <organization/>
</author> </author>
<date year="2008" month="January"/> <date month="January" year="2008"/>
<abstract> <abstract>
<t>This document defines algorithms for Authenticated Encryption w ith Associated Data (AEAD), and defines a uniform interface and a registry for s uch algorithms. The interface and registry can be used as an application-indepe ndent set of cryptoalgorithm suites. This approach provides advantages in effic iency and security, and promotes the reuse of crypto implementations. [STANDARD S-TRACK]</t> <t>This document defines algorithms for Authenticated Encryption w ith Associated Data (AEAD), and defines a uniform interface and a registry for s uch algorithms. The interface and registry can be used as an application-indepe ndent set of cryptoalgorithm suites. This approach provides advantages in effic iency and security, and promotes the reuse of crypto implementations. [STANDARD S-TRACK]</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="5116"/> <seriesInfo name="RFC" value="5116"/>
<seriesInfo name="DOI" value="10.17487/RFC5116"/> <seriesInfo name="DOI" value="10.17487/RFC5116"/>
</reference> </reference>
<reference anchor="HKDF" target="https://www.rfc-editor.org/info/rfc5869
">
<front>
<title>HMAC-based Extract-and-Expand Key Derivation Function (HKDF)<
/title>
<author initials="H." surname="Krawczyk" fullname="H. Krawczyk">
<organization/>
</author>
<author initials="P." surname="Eronen" fullname="P. Eronen">
<organization/>
</author>
<date year="2010" month="May"/>
<abstract>
<t>This document specifies a simple Hashed Message Authentication
Code (HMAC)-based key derivation function (HKDF), which can be used as a buildin
g block in various protocols and applications. The key derivation function (KDF
) is intended to support a wide range of applications and requirements, and is c
onservative in its use of cryptographic hash functions. This document is not an
Internet Standards Track specification; it is published for informational pur
poses.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5869"/>
<seriesInfo name="DOI" value="10.17487/RFC5869"/>
</reference>
<reference anchor="SHA"> <reference anchor="SHA">
<front> <front>
<title>Secure Hash Standard</title> <title>Secure Hash Standard</title>
<author initials="Q." surname="Dang" fullname="Quynh H. Dang"> <author fullname="Quynh H. Dang" initials="Q." surname="Dang">
<organization/> <organization/>
</author> </author>
<date year="2015" month="July"/> <date month="July" year="2015"/>
</front> </front>
<seriesInfo name="National Institute of Standards and Technology" valu e="report"/> <seriesInfo name="National Institute of Standards and Technology" valu e="report"/>
<seriesInfo name="DOI" value="10.6028/nist.fips.180-4"/> <seriesInfo name="DOI" value="10.6028/nist.fips.180-4"/>
</reference> </reference>
<reference anchor="CHACHA" target="https://www.rfc-editor.org/info/rfc84 39"> <reference anchor="CHACHA" target="https://www.rfc-editor.org/info/rfc84 39">
<front> <front>
<title>ChaCha20 and Poly1305 for IETF Protocols</title> <title>ChaCha20 and Poly1305 for IETF Protocols</title>
<author initials="Y." surname="Nir" fullname="Y. Nir"> <author fullname="Y. Nir" initials="Y." surname="Nir">
<organization/> <organization/>
</author> </author>
<author initials="A." surname="Langley" fullname="A. Langley"> <author fullname="A. Langley" initials="A." surname="Langley">
<organization/> <organization/>
</author> </author>
<date year="2018" month="June"/> <date month="June" year="2018"/>
<abstract> <abstract>
<t>This document defines the ChaCha20 stream cipher as well as the use of the Poly1305 authenticator, both as stand-alone algorithms and as a "com bined mode", or Authenticated Encryption with Associated Data (AEAD) algorithm.< /t> <t>This document defines the ChaCha20 stream cipher as well as the use of the Poly1305 authenticator, both as stand-alone algorithms and as a "com bined mode", or Authenticated Encryption with Associated Data (AEAD) algorithm.< /t>
<t>RFC 7539, the predecessor of this document, was meant to serve as a stable reference and an implementation guide. It was a product of the Cryp to Forum Research Group (CFRG). This document merges the errata filed against R FC 7539 and adds a little text to the Security Considerations section.</t> <t>RFC 7539, the predecessor of this document, was meant to serve as a stable reference and an implementation guide. It was a product of the Cryp to Forum Research Group (CFRG). This document merges the errata filed against R FC 7539 and adds a little text to the Security Considerations section.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="8439"/> <seriesInfo name="RFC" value="8439"/>
<seriesInfo name="DOI" value="10.17487/RFC8439"/> <seriesInfo name="DOI" value="10.17487/RFC8439"/>
</reference> </reference>
<reference anchor="AES"> <reference anchor="AES">
<front> <front>
<title>Advanced encryption standard (AES)</title> <title>Advanced encryption standard (AES)</title>
<author> <author>
<organization/> <organization/>
</author> </author>
<date year="2001" month="November"/> <date month="November" year="2001"/>
</front> </front>
<seriesInfo name="National Institute of Standards and Technology" valu e="report"/> <seriesInfo name="National Institute of Standards and Technology" valu e="report"/>
<seriesInfo name="DOI" value="10.6028/nist.fips.197"/> <seriesInfo name="DOI" value="10.6028/nist.fips.197"/>
</reference> </reference>
<reference anchor="ALPN" target="https://www.rfc-editor.org/info/rfc7301 "> <reference anchor="ALPN" target="https://www.rfc-editor.org/info/rfc7301 ">
<front> <front>
<title>Transport Layer Security (TLS) Application-Layer Protocol Neg otiation Extension</title> <title>Transport Layer Security (TLS) Application-Layer Protocol Neg otiation Extension</title>
<author initials="S." surname="Friedl" fullname="S. Friedl"> <author fullname="S. Friedl" initials="S." surname="Friedl">
<organization/> <organization/>
</author> </author>
<author initials="A." surname="Popov" fullname="A. Popov"> <author fullname="A. Popov" initials="A." surname="Popov">
<organization/> <organization/>
</author> </author>
<author initials="A." surname="Langley" fullname="A. Langley"> <author fullname="A. Langley" initials="A." surname="Langley">
<organization/> <organization/>
</author> </author>
<author initials="E." surname="Stephan" fullname="E. Stephan"> <author fullname="E. Stephan" initials="E." surname="Stephan">
<organization/> <organization/>
</author> </author>
<date year="2014" month="July"/> <date month="July" year="2014"/>
<abstract> <abstract>
<t>This document describes a Transport Layer Security (TLS) extens ion for application-layer protocol negotiation within the TLS handshake. For ins tances in which multiple application protocols are supported on the same TCP or UDP port, this extension allows the application layer to negotiate which protoco l will be used within the TLS connection.</t> <t>This document describes a Transport Layer Security (TLS) extens ion for application-layer protocol negotiation within the TLS handshake. For ins tances in which multiple application protocols are supported on the same TCP or UDP port, this extension allows the application layer to negotiate which protoco l will be used within the TLS connection.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="7301"/> <seriesInfo name="RFC" value="7301"/>
<seriesInfo name="DOI" value="10.17487/RFC7301"/> <seriesInfo name="DOI" value="10.17487/RFC7301"/>
</reference> </reference>
<reference anchor="RFC4086" target="https://www.rfc-editor.org/info/rfc4 086"> <reference anchor="RFC4086" target="https://www.rfc-editor.org/info/rfc4 086">
<front> <front>
<title>Randomness Requirements for Security</title> <title>Randomness Requirements for Security</title>
<author initials="D." surname="Eastlake 3rd" fullname="D. Eastlake 3 rd"> <author fullname="D. Eastlake 3rd" initials="D." surname="Eastlake 3 rd">
<organization/> <organization/>
</author> </author>
<author initials="J." surname="Schiller" fullname="J. Schiller"> <author fullname="J. Schiller" initials="J." surname="Schiller">
<organization/> <organization/>
</author> </author>
<author initials="S." surname="Crocker" fullname="S. Crocker"> <author fullname="S. Crocker" initials="S." surname="Crocker">
<organization/> <organization/>
</author> </author>
<date year="2005" month="June"/> <date month="June" year="2005"/>
<abstract> <abstract>
<t>Security systems are built on strong cryptographic algorithms t hat foil pattern analysis attempts. However, the security of these systems is d ependent on generating secret quantities for passwords, cryptographic keys, and similar quantities. The use of pseudo-random processes to generate secret quant ities can result in pseudo-security. A sophisticated attacker may find it easier to reproduce the environment that produced the secret quantities and to search the resulting small set of possibilities than to locate the quantities in the wh ole of the potential number space.</t> <t>Security systems are built on strong cryptographic algorithms t hat foil pattern analysis attempts. However, the security of these systems is d ependent on generating secret quantities for passwords, cryptographic keys, and similar quantities. The use of pseudo-random processes to generate secret quant ities can result in pseudo-security. A sophisticated attacker may find it easier to reproduce the environment that produced the secret quantities and to search the resulting small set of possibilities than to locate the quantities in the wh ole of the potential number space.</t>
<t>Choosing random quantities to foil a resourceful and motivated adversary is surprisingly difficult. This document points out many pitfalls in using poor entropy sources or traditional pseudo-random number generation techni ques for generating such quantities. It recommends the use of truly random hard ware techniques and shows that the existing hardware on many systems can be used for this purpose. It provides suggestions to ameliorate the problem when a hard ware solution is not available, and it gives examples of how large such quantiti es need to be for some applications. This document specifies an Internet Best C urrent Practices for the Internet Community, and requests discussion and suggest ions for improvements.</t> <t>Choosing random quantities to foil a resourceful and motivated adversary is surprisingly difficult. This document points out many pitfalls in using poor entropy sources or traditional pseudo-random number generation techni ques for generating such quantities. It recommends the use of truly random hard ware techniques and shows that the existing hardware on many systems can be used for this purpose. It provides suggestions to ameliorate the problem when a hard ware solution is not available, and it gives examples of how large such quantiti es need to be for some applications. This document specifies an Internet Best C urrent Practices for the Internet Community, and requests discussion and suggest ions for improvements.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="BCP" value="106"/> <seriesInfo name="BCP" value="106"/>
<seriesInfo name="RFC" value="4086"/> <seriesInfo name="RFC" value="4086"/>
<seriesInfo name="DOI" value="10.17487/RFC4086"/> <seriesInfo name="DOI" value="10.17487/RFC4086"/>
</reference> </reference>
<reference anchor="TLS-REGISTRIES" target="https://www.rfc-editor.org/in fo/rfc8447"> <reference anchor="TLS-REGISTRIES" target="https://www.rfc-editor.org/in fo/rfc8447">
<front> <front>
<title>IANA Registry Updates for TLS and DTLS</title> <title>IANA Registry Updates for TLS and DTLS</title>
<author initials="J." surname="Salowey" fullname="J. Salowey"> <author fullname="J. Salowey" initials="J." surname="Salowey">
<organization/> <organization/>
</author> </author>
<author initials="S." surname="Turner" fullname="S. Turner"> <author fullname="S. Turner" initials="S." surname="Turner">
<organization/> <organization/>
</author> </author>
<date year="2018" month="August"/> <date month="August" year="2018"/>
<abstract> <abstract>
<t>This document describes a number of changes to TLS and DTLS IAN A registries that range from adding notes to the registry all the way to changin g the registration policy. These changes were mostly motivated by WG review of the TLS- and DTLS-related registries undertaken as part of the TLS 1.3 developme nt process.</t> <t>This document describes a number of changes to TLS and DTLS IAN A registries that range from adding notes to the registry all the way to changin g the registration policy. These changes were mostly motivated by WG review of the TLS- and DTLS-related registries undertaken as part of the TLS 1.3 developme nt process.</t>
<t>This document updates the following RFCs: 3749, 5077, 4680, 524 6, 5705, 5878, 6520, and 7301.</t> <t>This document updates the following RFCs: 3749, 5077, 4680, 524 6, 5705, 5878, 6520, and 7301.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="8447"/> <seriesInfo name="RFC" value="8447"/>
<seriesInfo name="DOI" value="10.17487/RFC8447"/> <seriesInfo name="DOI" value="10.17487/RFC8447"/>
</reference> </reference>
</references> </references>
<references> <references>
<name>Informative References</name> <name>Informative References</name>
<reference anchor="AEBounds" target="http://www.isg.rhul.ac.uk/~kp/TLS-A Ebounds.pdf"> <reference anchor="AEBounds" target="https://www.isg.rhul.ac.uk/~kp/TLS- AEbounds.pdf">
<front> <front>
<title>Limits on Authenticated Encryption Use in TLS</title> <title>Limits on Authenticated Encryption Use in TLS</title>
<author initials="A." surname="Luykx"> <author initials="A." surname="Luykx">
<organization/> <organization/>
</author> </author>
<author initials="K." surname="Paterson"> <author initials="K." surname="Paterson">
<organization/> <organization/>
</author> </author>
<date year="2016" month="March" day="08"/> <date year="2017" month="August" day="28"/>
</front> </front>
</reference> </reference>
<reference anchor="IMC"> <reference anchor="IMC">
<front> <front>
<title>Introduction to Modern Cryptography, Second Edition</title> <title>Introduction to Modern Cryptography, Second Edition</title>
<author initials="J." surname="Katz"> <author initials="J." surname="Katz">
<organization/> <organization/>
</author> </author>
<author initials="Y." surname="Lindell"> <author initials="Y." surname="Lindell">
<organization/> <organization/>
skipping to change at line 2042 skipping to change at line 2013
<date year="2014" month="November" day="06"/> <date year="2014" month="November" day="06"/>
</front> </front>
<seriesInfo name="ISBN" value="978-1466570269"/> <seriesInfo name="ISBN" value="978-1466570269"/>
</reference> </reference>
<reference anchor="QUIC-HTTP"> <reference anchor="QUIC-HTTP">
<front> <front>
<title>Hypertext Transfer Protocol Version 3 (HTTP/3)</title> <title>Hypertext Transfer Protocol Version 3 (HTTP/3)</title>
<author initials="M." surname="Bishop" fullname="Mike Bishop" role=" editor"> <author initials="M." surname="Bishop" fullname="Mike Bishop" role=" editor">
<organization>Akamai Technologies</organization> <organization>Akamai Technologies</organization>
</author> </author>
<date year="2021" month="January" day="15"/> <date year="2021" month="February" day="2"/>
</front> </front>
<seriesInfo name="Internet-Draft" value="draft-ietf-quic-http-33"/> <seriesInfo name="Internet-Draft" value="draft-ietf-quic-http"/>
</reference> </reference>
<reference anchor="ROBUST" target="https://eprint.iacr.org/2020/718"> <reference anchor="ROBUST" target="https://eprint.iacr.org/2020/718">
<front> <front>
<title>Robust Channels: Handling Unreliable Networks in the Record L ayers of QUIC and DTLS 1.3</title> <title>Robust Channels: Handling Unreliable Networks in the Record L ayers of QUIC and DTLS 1.3</title>
<author initials="M." surname="Fischlin"> <author initials="M." surname="Fischlin">
<organization/> <organization/>
</author> </author>
<author initials="F." surname="Günther"> <author initials="F." surname="Günther">
<organization/> <organization/>
</author> </author>
<author initials="C." surname="Janson"> <author initials="C." surname="Janson">
<organization/> <organization/>
</author> </author>
<date year="2020" month="May" day="16"/> <date year="2020" month="May" day="16"/>
</front> </front>
</reference> </reference>
<reference anchor="CCM-ANALYSIS">
<front>
<title>On the Security of CTR + CBC-MAC</title>
<author initials="J." surname="Jonsson" fullname="Jakob Jonsson">
<organization/>
</author>
<date year="2003"/>
</front>
<seriesInfo name="DOI" value="10.1007/3-540-36492-7_7"/>
<refcontent>Selected Areas in Cryptography</refcontent>
<refcontent>SAC 2002</refcontent>
<refcontent>Lecture Notes in Computer Science, vol 2595</refcontent>
<refcontent>pp. 76-93</refcontent>
</reference>
<reference anchor="NAN">
<front>
<title>Nonces Are Noticed: AEAD Revisited</title>
<author initials="M." surname="Bellare" fullname="Mihir Bellare">
<organization/>
</author>
<author initials="R." surname="Ng" fullname="Ruth Ng">
<organization/>
</author>
<author initials="B." surname="Tackmann" fullname="Björn Tackmann">
<organization/>
</author>
<date year="2019"/>
</front>
<seriesInfo name="DOI" value="10.1007/978-3-030-26948-7_9"/>
<refcontent>Advances in Cryptology - CRYPTO 2019</refcontent>
<refcontent>Lecture Notes in Computer Science, vol 11692</refcontent>
<refcontent>pp. 235-265</refcontent>
</reference>
<reference anchor="GCM-MU">
<front>
<title>The Multi-user Security of GCM, Revisited: Tight Bounds for N
once Randomization</title>
<author initials="V." surname="Hoang" fullname="Viet Tung Hoang">
<organization/>
</author>
<author initials="S." surname="Tessaro" fullname="Stefano Tessaro">
<organization/>
</author>
<author initials="A." surname="Thiruvengadam" fullname="Aishwarya Th
iruvengadam">
<organization/>
</author>
<date year="2018"/>
</front>
<seriesInfo name="DOI" value="10.1145/3243734.3243816"/>
<refcontent>CCS '18: Proceedings of the 2018 ACM SIGSAC Conference on
Computer and Communications Security</refcontent>
<refcontent>pp. 1429-1440</refcontent>
</reference>
<reference anchor="RFC5280" target="https://www.rfc-editor.org/info/rfc5 280"> <reference anchor="RFC5280" target="https://www.rfc-editor.org/info/rfc5 280">
<front> <front>
<title>Internet X.509 Public Key Infrastructure Certificate and Cert ificate Revocation List (CRL) Profile</title> <title>Internet X.509 Public Key Infrastructure Certificate and Cert ificate Revocation List (CRL) Profile</title>
<author initials="D." surname="Cooper" fullname="D. Cooper"> <author fullname="D. Cooper" initials="D." surname="Cooper">
<organization/> <organization/>
</author> </author>
<author initials="S." surname="Santesson" fullname="S. Santesson"> <author fullname="S. Santesson" initials="S." surname="Santesson">
<organization/> <organization/>
</author> </author>
<author initials="S." surname="Farrell" fullname="S. Farrell"> <author fullname="S. Farrell" initials="S." surname="Farrell">
<organization/> <organization/>
</author> </author>
<author initials="S." surname="Boeyen" fullname="S. Boeyen"> <author fullname="S. Boeyen" initials="S." surname="Boeyen">
<organization/> <organization/>
</author> </author>
<author initials="R." surname="Housley" fullname="R. Housley"> <author fullname="R. Housley" initials="R." surname="Housley">
<organization/> <organization/>
</author> </author>
<author initials="W." surname="Polk" fullname="W. Polk"> <author fullname="W. Polk" initials="W." surname="Polk">
<organization/> <organization/>
</author> </author>
<date year="2008" month="May"/> <date month="May" year="2008"/>
<abstract> <abstract>
<t>This memo profiles the X.509 v3 certificate and X.509 v2 certif icate revocation list (CRL) for use in the Internet. An overview of this approa ch and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and seman tics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate ext ensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certificatio n path validation is described. An ASN.1 module and examples are provided in th e appendices. [STANDARDS-TRACK]</t> <t>This memo profiles the X.509 v3 certificate and X.509 v2 certif icate revocation list (CRL) for use in the Internet. An overview of this approa ch and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and seman tics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate ext ensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certificatio n path validation is described. An ASN.1 module and examples are provided in th e appendices. [STANDARDS-TRACK]</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="5280"/> <seriesInfo name="RFC" value="5280"/>
<seriesInfo name="DOI" value="10.17487/RFC5280"/> <seriesInfo name="DOI" value="10.17487/RFC5280"/>
</reference> </reference>
<reference anchor="RFC2818" target="https://www.rfc-editor.org/info/rfc2 818"> <reference anchor="RFC2818" target="https://www.rfc-editor.org/info/rfc2 818">
<front> <front>
<title>HTTP Over TLS</title> <title>HTTP Over TLS</title>
<author initials="E." surname="Rescorla" fullname="E. Rescorla"> <author fullname="E. Rescorla" initials="E." surname="Rescorla">
<organization/> <organization/>
</author> </author>
<date year="2000" month="May"/> <date month="May" year="2000"/>
<abstract> <abstract>
<t>This memo describes how to use Transport Layer Security (TLS) t o secure Hypertext Transfer Protocol (HTTP) connections over the Internet. This memo provides information for the Internet community.</t> <t>This memo describes how to use Transport Layer Security (TLS) t o secure Hypertext Transfer Protocol (HTTP) connections over the Internet. This memo provides information for the Internet community.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="2818"/> <seriesInfo name="RFC" value="2818"/>
<seriesInfo name="DOI" value="10.17487/RFC2818"/> <seriesInfo name="DOI" value="10.17487/RFC2818"/>
</reference> </reference>
<reference anchor="COMPRESS" target="http://www.ietf.org/internet-drafts /draft-ietf-tls-certificate-compression-10.txt"> <reference anchor="COMPRESS" target="https://www.rfc-editor.org/info/rfc 8879">
<front> <front>
<title>TLS Certificate Compression</title> <title>TLS Certificate Compression</title>
<author initials="A" surname="Ghedini" fullname="Alessandro Ghedini" > <author fullname="A. Ghedini" initials="A." surname="Ghedini">
<organization/> <organization/>
</author> </author>
<author initials="V" surname="Vasiliev" fullname="Victor Vasiliev"> <author fullname="V. Vasiliev" initials="V." surname="Vasiliev">
<organization/> <organization/>
</author> </author>
<date month="January" day="6" year="2020"/> <date month="December" year="2020"/>
<abstract> <abstract>
<t>In TLS handshakes, certificate chains often take up the majorit <t>In TLS handshakes, certificate chains often take up the majorit
y of the bytes transmitted. This document describes how certificate chains can y of the bytes transmitted.</t>
be compressed to reduce the amount of data transmitted and avoid some round trip <t>This document describes how certificate chains can be compresse
s.</t> d to reduce the amount of data transmitted and avoid some round trips.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="Internet-Draft" value="draft-ietf-tls-certificate-co <seriesInfo name="RFC" value="8879"/>
mpression-10"/> <seriesInfo name="DOI" value="10.17487/RFC8879"/>
</reference> </reference>
<reference anchor="HTTP2-TLS13" target="https://www.rfc-editor.org/info/ rfc8740"> <reference anchor="HTTP2-TLS13" target="https://www.rfc-editor.org/info/ rfc8740">
<front> <front>
<title>Using TLS 1.3 with HTTP/2</title> <title>Using TLS 1.3 with HTTP/2</title>
<author initials="D." surname="Benjamin" fullname="D. Benjamin"> <author fullname="D. Benjamin" initials="D." surname="Benjamin">
<organization/> <organization/>
</author> </author>
<date year="2020" month="February"/> <date month="February" year="2020"/>
<abstract> <abstract>
<t>This document updates RFC 7540 by forbidding TLS 1.3 post-hands hake authentication, as an analog to the existing TLS 1.2 renegotiation restrict ion.</t> <t>This document updates RFC 7540 by forbidding TLS 1.3 post-hands hake authentication, as an analog to the existing TLS 1.2 renegotiation restrict ion.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="8740"/> <seriesInfo name="RFC" value="8740"/>
<seriesInfo name="DOI" value="10.17487/RFC8740"/> <seriesInfo name="DOI" value="10.17487/RFC8740"/>
</reference> </reference>
<reference anchor="ASCII" target="https://www.rfc-editor.org/info/rfc20" > <reference anchor="ASCII" target="https://www.rfc-editor.org/info/rfc20" >
<front> <front>
<title>ASCII format for network interchange</title> <title>ASCII format for network interchange</title>
<author initials="V.G." surname="Cerf" fullname="V.G. Cerf"> <author fullname="V.G. Cerf" initials="V.G." surname="Cerf">
<organization/> <organization/>
</author> </author>
<date year="1969" month="October"/> <date month="October" year="1969"/>
</front> </front>
<seriesInfo name="STD" value="80"/> <seriesInfo name="STD" value="80"/>
<seriesInfo name="RFC" value="20"/> <seriesInfo name="RFC" value="20"/>
<seriesInfo name="DOI" value="10.17487/RFC0020"/> <seriesInfo name="DOI" value="10.17487/RFC0020"/>
</reference> </reference>
<reference anchor="HTTP-REPLAY" target="https://www.rfc-editor.org/info/ rfc8470"> <reference anchor="HTTP-REPLAY" target="https://www.rfc-editor.org/info/ rfc8470">
<front> <front>
<title>Using Early Data in HTTP</title> <title>Using Early Data in HTTP</title>
<author initials="M." surname="Thomson" fullname="M. Thomson"> <author fullname="M. Thomson" initials="M." surname="Thomson">
<organization/> <organization/>
</author> </author>
<author initials="M." surname="Nottingham" fullname="M. Nottingham"> <author fullname="M. Nottingham" initials="M." surname="Nottingham">
<organization/> <organization/>
</author> </author>
<author initials="W." surname="Tarreau" fullname="W. Tarreau"> <author fullname="W. Tarreau" initials="W." surname="Tarreau">
<organization/> <organization/>
</author> </author>
<date year="2018" month="September"/> <date month="September" year="2018"/>
<abstract> <abstract>
<t>Using TLS early data creates an exposure to the possibility of a replay attack. This document defines mechanisms that allow clients to communi cate with servers about HTTP requests that are sent in early data. Techniques a re described that use these mechanisms to mitigate the risk of replay.</t> <t>Using TLS early data creates an exposure to the possibility of a replay attack. This document defines mechanisms that allow clients to communi cate with servers about HTTP requests that are sent in early data. Techniques a re described that use these mechanisms to mitigate the risk of replay.</t>
</abstract> </abstract>
</front> </front>
<seriesInfo name="RFC" value="8470"/> <seriesInfo name="RFC" value="8470"/>
<seriesInfo name="DOI" value="10.17487/RFC8470"/> <seriesInfo name="DOI" value="10.17487/RFC8470"/>
</reference> </reference>
<reference anchor="GCM-MU">
<front>
<title>The Multi-user Security of GCM, Revisited: Tight Bounds for N
once Randomization</title>
<author initials="V." surname="Hoang" fullname="Viet Tung Hoang">
<organization/>
</author>
<author initials="S." surname="Tessaro" fullname="Stefano Tessaro">
<organization/>
</author>
<author initials="A." surname="Thiruvengadam" fullname="Aishwarya Th
iruvengadam">
<organization/>
</author>
<date year="2018" month="January"/>
</front>
<seriesInfo name="Proceedings of the 2018 ACM SIGSAC Conference on Com
puter and Communications" value="Security"/>
<seriesInfo name="DOI" value="10.1145/3243734.3243816"/>
</reference>
<reference anchor="NAN">
<front>
<title>Nonces Are Noticed: AEAD Revisited</title>
<author initials="M." surname="Bellare" fullname="Mihir Bellare">
<organization/>
</author>
<author initials="R." surname="Ng" fullname="Ruth Ng">
<organization/>
</author>
<author initials="B." surname="Tackmann" fullname="Björn Tackmann">
<organization/>
</author>
<date year="2019"/>
</front>
<seriesInfo name="Advances in Cryptology - CRYPTO 2019" value="pp. 235
-265"/>
<seriesInfo name="DOI" value="10.1007/978-3-030-26948-7_9"/>
</reference>
<reference anchor="CCM-ANALYSIS">
<front>
<title>On the Security of CTR + CBC-MAC</title>
<author initials="J." surname="Jonsson" fullname="Jakob Jonsson">
<organization/>
</author>
<date year="2003"/>
</front>
<seriesInfo name="Selected Areas in Cryptography" value="pp. 76-93"/>
<seriesInfo name="DOI" value="10.1007/3-540-36492-7_7"/>
</reference>
</references> </references>
</references> </references>
<section anchor="test-vectors" numbered="true" toc="default"> <section anchor="test-vectors" numbered="true" toc="default">
<name>Sample Packet Protection</name> <name>Sample Packet Protection</name>
<t>This section shows examples of packet protection so that implementation s can be <t>This section shows examples of packet protection so that implementation s can be
verified incrementally. Samples of Initial packets from both client and server, verified incrementally. Samples of Initial packets from both client and server
plus a Retry packet are defined. These packets use an 8-byte client-chosen plus a Retry packet are defined. These packets use an 8-byte client-chosen
Destination Connection ID of 0x8394c8f03e515708. Some intermediate values are Destination Connection ID of 0x8394c8f03e515708. Some intermediate values are
included. All values are shown in hexadecimal.</t> included. All values are shown in hexadecimal.</t>
<section anchor="keys" numbered="true" toc="default"> <section anchor="keys" numbered="true" toc="default">
<name>Keys</name> <name>Keys</name>
<t>The labels generated during the execution of the HKDF-Expand-Label fu nction <t>The labels generated during the execution of the HKDF-Expand-Label fu nction
(that is, HkdfLabel.label) and part of the value given to the HKDF-Expand (that is, HkdfLabel.label) and part of the value given to the HKDF-Expand
function in order to produce its output are:</t> function in order to produce its output are:</t>
<dl> <dl>
<dt> <dt>client in:</dt>
client in: </dt>
<dd> <dd>
<t>00200f746c73313320636c69656e7420696e00</t> <t>00200f746c73313320636c69656e7420696e00</t>
</dd> </dd>
<dt> <dt>server in:</dt>
server in: </dt>
<dd> <dd>
<t>00200f746c7331332073657276657220696e00</t> <t>00200f746c7331332073657276657220696e00</t>
</dd> </dd>
<dt> <dt>quic key:</dt>
quic key: </dt>
<dd> <dd>
<t>00100e746c7331332071756963206b657900</t> <t>00100e746c7331332071756963206b657900</t>
</dd> </dd>
<dt> <dt>quic iv:</dt>
quic iv: </dt>
<dd> <dd>
<t>000c0d746c733133207175696320697600</t> <t>000c0d746c733133207175696320697600</t>
</dd> </dd>
<dt> <dt>quic hp:</dt>
quic hp: </dt>
<dd> <dd>
<t>00100d746c733133207175696320687000</t> <t>00100d746c733133207175696320687000</t>
</dd> </dd>
</dl> </dl>
<t>The initial secret is common:</t> <t>The initial secret is common:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
initial_secret = HKDF-Extract(initial_salt, cid) initial_secret = HKDF-Extract(initial_salt, cid)
= 7db5df06e7a69e432496adedb0085192 = 7db5df06e7a69e432496adedb0085192
3595221596ae2ae9fb8115c1e9ed0a44 3595221596ae2ae9fb8115c1e9ed0a44
]]></artwork> ]]></artwork>
skipping to change at line 2314 skipping to change at line 2288
75300901100f088394c8f03e51570806 048000ffff 75300901100f088394c8f03e51570806 048000ffff
]]></artwork> ]]></artwork>
<t>The unprotected header indicates a length of 1182 bytes: the 4-byte p acket <t>The unprotected header indicates a length of 1182 bytes: the 4-byte p acket
number, 1162 bytes of frames, and the 16-byte authentication tag. The header number, 1162 bytes of frames, and the 16-byte authentication tag. The header
includes the connection ID and a packet number of 2:</t> includes the connection ID and a packet number of 2:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
c300000001088394c8f03e5157080000449e00000002 c300000001088394c8f03e5157080000449e00000002
]]></artwork> ]]></artwork>
<t>Protecting the payload produces output that is sampled for header pro tection. <t>Protecting the payload produces output that is sampled for header pro tection.
Because the header uses a 4-byte packet number encoding, the first 16 bytes of Because the header uses a 4-byte packet number encoding, the first 16 bytes of
the protected payload is sampled, then applied to the header:</t> the protected payload is sampled and then applied to the header as follows:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
sample = d1b1c98dd7689fb8ec11d242b123dc9b sample = d1b1c98dd7689fb8ec11d242b123dc9b
mask = AES-ECB(hp, sample)[0..4] mask = AES-ECB(hp, sample)[0..4]
= 437b9aec36 = 437b9aec36
header[0] ^= mask[0] & 0x0f header[0] ^= mask[0] & 0x0f
= c0 = c0
header[18..21] ^= mask[1..4] header[18..21] ^= mask[1..4]
= 7b9aec34 = 7b9aec34
skipping to change at line 2473 skipping to change at line 2447
</section> </section>
</section> </section>
<section anchor="aead-analysis" numbered="true" toc="default"> <section anchor="aead-analysis" numbered="true" toc="default">
<name>AEAD Algorithm Analysis</name> <name>AEAD Algorithm Analysis</name>
<t>This section documents analyses used in deriving AEAD algorithm limits for <t>This section documents analyses used in deriving AEAD algorithm limits for
AEAD_AES_128_GCM, AEAD_AES_128_CCM, and AEAD_AES_256_GCM. The analyses that AEAD_AES_128_GCM, AEAD_AES_128_CCM, and AEAD_AES_256_GCM. The analyses that
follow use symbols for multiplication (*), division (/), and exponentiation (^), follow use symbols for multiplication (*), division (/), and exponentiation (^),
plus parentheses for establishing precedence. The following symbols are also plus parentheses for establishing precedence. The following symbols are also
used:</t> used:</t>
<dl> <dl>
<dt> <dt>t:</dt>
t: </dt>
<dd> <dd>
<t>The size of the authentication tag in bits. For these ciphers, t is 128.</t> <t>The size of the authentication tag in bits. For these ciphers, t is 128.</t>
</dd> </dd>
<dt> <dt>n:</dt>
n: </dt>
<dd> <dd>
<t>The size of the block function in bits. For these ciphers, n is 128 .</t> <t>The size of the block function in bits. For these ciphers, n is 128 .</t>
</dd> </dd>
<dt> <dt>k:</dt>
k: </dt>
<dd> <dd>
<t>The size of the key in bits. This is 128 for AEAD_AES_128_GCM and <t>The size of the key in bits. This is 128 for AEAD_AES_128_GCM and
AEAD_AES_128_CCM; 256 for AEAD_AES_256_GCM.</t> AEAD_AES_128_CCM; 256 for AEAD_AES_256_GCM.</t>
</dd> </dd>
<dt> <dt>l:</dt>
l: </dt>
<dd> <dd>
<t>The number of blocks in each packet (see below).</t> <t>The number of blocks in each packet (see below).</t>
</dd> </dd>
<dt> <dt>q:</dt>
q: </dt>
<dd> <dd>
<t>The number of genuine packets created and protected by endpoints. T his value <t>The number of genuine packets created and protected by endpoints. T his value
is the bound on the number of packets that can be protected before updating is the bound on the number of packets that can be protected before updating
keys.</t> keys.</t>
</dd> </dd>
<dt> <dt>v:</dt>
v: </dt>
<dd> <dd>
<t>The number of forged packets that endpoints will accept. This value is the <t>The number of forged packets that endpoints will accept. This value is the
bound on the number of forged packets that an endpoint can reject before bound on the number of forged packets that an endpoint can reject before
updating keys.</t> updating keys.</t>
</dd> </dd>
<dt> <dt>o:</dt>
o: </dt>
<dd> <dd>
<t>The amount of offline ideal cipher queries made by an adversary.</t > <t>The amount of offline ideal cipher queries made by an adversary.</t >
</dd> </dd>
</dl> </dl>
<t>The analyses that follow rely on a count of the number of block operati ons <t>The analyses that follow rely on a count of the number of block operati ons
involved in producing each message. This analysis is performed for packets of involved in producing each message. This analysis is performed for packets of
size up to 2^11 (l = 2^7) and 2^16 (l = 2^12). A size of 2^11 is expected to be size up to 2<sup>11</sup> (l = 2<sup>7</sup>) and 2<sup>16</sup> (l =
a limit that matches common deployment patterns, whereas the 2^16 is the maximum 2<sup>12</sup>). A size of 2<sup>11</sup> is expected to be a limit that matches
possible size of a QUIC packet. Only endpoints that strictly limit packet size common deployment patterns, whereas the 2<sup>16</sup> is the maximum possible
can use the larger confidentiality and integrity limits that are derived using size of a QUIC packet. Only endpoints that strictly limit packet size can use
the smaller packet size.</t> the larger confidentiality and integrity limits that are derived using the
smaller packet size.</t>
<t>For AEAD_AES_128_GCM and AEAD_AES_256_GCM, the message length (l) is th e length <t>For AEAD_AES_128_GCM and AEAD_AES_256_GCM, the message length (l) is th e length
of the associated data in blocks plus the length of the plaintext in blocks.</t> of the associated data in blocks plus the length of the plaintext in blocks.</t>
<t>For AEAD_AES_128_CCM, the total number of block cipher operations is th <t>For AEAD_AES_128_CCM, the total number of block cipher operations is th
e sum e sum of
of: the length of the associated data in blocks, the length of the ciphertext the following: the length of the associated data in blocks, the length of the
in blocks, the length of the plaintext in blocks, plus 1. In this analysis, ciphertext in blocks, the length of the plaintext in blocks, plus 1. In this
this is simplified to a value of twice the length of the packet in blocks (that analysis, this is simplified to a value of twice the length of the packet in
is, <tt>2l = 2^8</tt> for packets that are limited to 2^11 bytes, or <tt>2l = 2^ blocks (that is, <tt>2l = 2<sup>8</sup></tt> for packets that are limited to
13</tt> 2<sup>11</sup> bytes, or <tt>2l = 2<sup>13</sup></tt> otherwise). This
otherwise). This simplification is based on the packet containing all of the simplification is based on the packet containing all of the associated data and
associated data and ciphertext. This results in a 1 to 3 block overestimation ciphertext. This results in a one to three block overestimation of the number of
of the number of operations per packet.</t> operations per packet.</t>
<section anchor="gcm-bounds" numbered="true" toc="default"> <section anchor="gcm-bounds" numbered="true" toc="default">
<name>Analysis of AEAD_AES_128_GCM and AEAD_AES_256_GCM Usage Limits</na me> <name>Analysis of AEAD_AES_128_GCM and AEAD_AES_256_GCM Usage Limits</na me>
<t><xref target="GCM-MU" format="default"/> specify concrete bounds for <t><xref target="GCM-MU" format="default"/> specifies concrete bounds fo
AEAD_AES_128_GCM and AEAD_AES_256_GCM as r AEAD_AES_128_GCM and AEAD_AES_256_GCM
used in TLS 1.3 and QUIC. This section documents this analysis using several as used in TLS 1.3 and QUIC. This section documents this analysis using several
simplifying assumptions:</t> simplifying assumptions:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>The number of ciphertext blocks an attacker uses in forgery attemp ts is <li>The number of ciphertext blocks an attacker uses in forgery attemp ts is
bounded by v * l, the number of forgery attempts and the size of each packet (in bounded by v * l, which is the number of forgery attempts multiplied by the
blocks).</li> size of each packet (in blocks).</li>
<li>The amount of offline work done by an attacker does not dominate o ther factors <li>The amount of offline work done by an attacker does not dominate o ther factors
in the analysis.</li> in the analysis.</li>
</ul> </ul>
<t>The bounds in <xref target="GCM-MU" format="default"/> are tighter an d more complete than those used in <t>The bounds in <xref target="GCM-MU" format="default"/> are tighter an d more complete than those used in
<xref target="AEBounds" format="default"/>, which allows for larger limits than those described in <xref target="AEBounds" format="default"/>, which allows for larger limits than those described in
<xref target="TLS13" format="default"/>.</t> <xref target="TLS13" format="default"/>.</t>
<section anchor="confidentiality-limit" numbered="true" toc="default"> <section anchor="confidentiality-limit" numbered="true" toc="default">
<name>Confidentiality Limit</name> <name>Confidentiality Limit</name>
<t>For confidentiality, Theorum (4.3) in <xref target="GCM-MU" format= <t>For confidentiality, Theorem (4.3) in <xref target="GCM-MU" format=
"default"/> establishes that - for a "default"/> establishes that, for a single
single user that does not repeat nonces - the dominant term in determining the user that does not repeat nonces, the dominant term in determining the
distinguishing advantage between a real and random AEAD algorithm gained by an distinguishing advantage between a real and random AEAD algorithm gained by an
attacker is:</t> attacker is:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
2 * (q * l)^2 / 2^n 2 * (q * l)^2 / 2^n
]]></artwork> ]]></artwork>
<t>For a target advantage of 2^-57, this results in the relation:</t> <t>For a target advantage of 2<sup>-57</sup>, this results in the rela tion:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
q <= 2^35 / l q <= 2^35 / l
]]></artwork> ]]></artwork>
<t>Thus, endpoints that do not send packets larger than 2^11 bytes can <t>Thus, endpoints that do not send packets larger than 2<sup>11</sup>
not protect bytes cannot
more than 2^28 packets in a single connection without causing an attacker to protect more than 2<sup>28</sup> packets in a single connection without causing
gain an larger advantage than the target of 2^-57. The limit for endpoints that an attacker to gain a more significant advantage than the target of
allow for the packet size to be as large as 2^16 is instead 2^23.</t> 2<sup>-57</sup>. The limit for endpoints that allow for the packet size to be as
large as 2<sup>16</sup> is instead 2<sup>23</sup>.</t>
</section> </section>
<section anchor="integrity-limit" numbered="true" toc="default"> <section anchor="integrity-limit" numbered="true" toc="default">
<name>Integrity Limit</name> <name>Integrity Limit</name>
<t>For integrity, Theorem (4.3) in <xref target="GCM-MU" format="defau lt"/> establishes that an attacker gains <t>For integrity, Theorem (4.3) in <xref target="GCM-MU" format="defau lt"/> establishes that an attacker gains
an advantage in successfully forging a packet of no more than:</t> an advantage in successfully forging a packet of no more than the following:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
(1 / 2^(8 * n)) + ((2 * v) / 2^(2 * n)) (1 / 2^(8 * n)) + ((2 * v) / 2^(2 * n))
+ ((2 * o * v) / 2^(k + n)) + (n * (v + (v * l)) / 2^k) + ((2 * o * v) / 2^(k + n)) + (n * (v + (v * l)) / 2^k)
]]></artwork> ]]></artwork>
<t>The goal is to limit this advantage to 2^-57. For AEAD_AES_128_GCM <t>The goal is to limit this advantage to 2<sup>-57</sup>. For AEAD_A
, the fourth ES_128_GCM,
term in this inequality dominates the rest, so the others can be removed without the fourth term in this inequality dominates the rest, so the others can be
significant effect on the result. This produces the following approximation:</t> removed without significant effect on the result. This produces the following
approximation:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
v <= 2^64 / l v <= 2^64 / l
]]></artwork> ]]></artwork>
<t>Endpoints that do not attempt to remove protection from packets lar <t>Endpoints that do not attempt to remove protection from packets lar
ger than 2^11 ger than
bytes can attempt to remove protection from at most 2^57 packets. Endpoints that 2<sup>11</sup> bytes can attempt to remove protection from at most
do not restrict the size of processed packets can attempt to remove protection 2<sup>57</sup> packets. Endpoints that do not restrict the size of processed
from at most 2^52 packets.</t> packets can attempt to remove protection from at most 2<sup>52</sup> packets.</t
>
<t>For AEAD_AES_256_GCM, the same term dominates, but the larger value of k <t>For AEAD_AES_256_GCM, the same term dominates, but the larger value of k
produces the following approximation:</t> produces the following approximation:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
v <= 2^192 / l v <= 2^192 / l
]]></artwork> ]]></artwork>
<t>This is substantially larger than the limit for AEAD_AES_128_GCM. However, this <t>This is substantially larger than the limit for AEAD_AES_128_GCM. However, this
document recommends that the same limit be applied to both functions as either document recommends that the same limit be applied to both functions as either
limit is acceptably large.</t> limit is acceptably large.</t>
</section> </section>
</section> </section>
skipping to change at line 2603 skipping to change at line 2574
<name>Analysis of AEAD_AES_128_CCM Usage Limits</name> <name>Analysis of AEAD_AES_128_CCM Usage Limits</name>
<t>TLS <xref target="TLS13" format="default"/> and <xref target="AEBound s" format="default"/> do not specify limits on usage <t>TLS <xref target="TLS13" format="default"/> and <xref target="AEBound s" format="default"/> do not specify limits on usage
for AEAD_AES_128_CCM. However, any AEAD that is used with QUIC requires limits for AEAD_AES_128_CCM. However, any AEAD that is used with QUIC requires limits
on use that ensure that both confidentiality and integrity are preserved. This on use that ensure that both confidentiality and integrity are preserved. This
section documents that analysis.</t> section documents that analysis.</t>
<t><xref target="CCM-ANALYSIS" format="default"/> is used as the basis o f this <t><xref target="CCM-ANALYSIS" format="default"/> is used as the basis o f this
analysis. The results of that analysis are used to derive usage limits that are analysis. The results of that analysis are used to derive usage limits that are
based on those chosen in <xref target="TLS13" format="default"/>.</t> based on those chosen in <xref target="TLS13" format="default"/>.</t>
<t>For confidentiality, Theorem 2 in <xref target="CCM-ANALYSIS" format= "default"/> establishes that an attacker <t>For confidentiality, Theorem 2 in <xref target="CCM-ANALYSIS" format= "default"/> establishes that an attacker
gains a distinguishing advantage over an ideal pseudorandom permutation (PRP) of gains a distinguishing advantage over an ideal pseudorandom permutation (PRP) of
no more than:</t> no more than the following:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
(2l * q)^2 / 2^n (2l * q)^2 / 2^n
]]></artwork> ]]></artwork>
<t>The integrity limit in Theorem 1 in <xref target="CCM-ANALYSIS" forma t="default"/> provides an attacker a <t>The integrity limit in Theorem 1 in <xref target="CCM-ANALYSIS" forma t="default"/> provides an attacker a
strictly higher advantage for the same number of messages. As the targets for strictly higher advantage for the same number of messages. As the targets for
the confidentiality advantage and the integrity advantage are the same, only the confidentiality advantage and the integrity advantage are the same, only
Theorem 1 needs to be considered.</t> Theorem 1 needs to be considered.</t>
<t>Theorem 1 establishes that an attacker gains an advantage over an <t>Theorem 1 establishes that an attacker gains an advantage over an
ideal PRP of no more than:</t> ideal PRP of no more than the following:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
v / 2^t + (2l * (v + q))^2 / 2^n v / 2^t + (2l * (v + q))^2 / 2^n
]]></artwork> ]]></artwork>
<t>As <tt>t</tt> and <tt>n</tt> are both 128, the first term is negligib le relative to the <t>As <tt>t</tt> and <tt>n</tt> are both 128, the first term is negligib le relative to the
second, so that term can be removed without a significant effect on the result.< /t> second, so that term can be removed without a significant effect on the result.< /t>
<t>This produces a relation that combines both encryption and decryption attempts <t>This produces a relation that combines both encryption and decryption attempts
with the same limit as that produced by the theorem for confidentiality alone. with the same limit as that produced by the theorem for confidentiality alone.
For a target advantage of 2^-57, this results in:</t> For a target advantage of 2<sup>-57</sup>, this results in the following:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
v + q <= 2^34.5 / l v + q <= 2^34.5 / l
]]></artwork> ]]></artwork>
<t>By setting <tt>q = v</tt>, values for both confidentiality and integr ity limits can be <t>By setting <tt>q = v</tt>, values for both confidentiality and integr ity limits can be
produced. Endpoints that limit packets to 2^11 bytes therefore have both produced. Endpoints that limit packets to 2<sup>11</sup> bytes therefore have
confidentiality and integrity limits of 2^26.5 packets. Endpoints that do not both confidentiality and integrity limits of 2<sup>26.5</sup> packets. Endpoints
restrict packet size have a limit of 2^21.5.</t> that do not restrict packet size have a limit of 2<sup>21.5</sup>.</t>
</section>
</section>
<section anchor="change-log" numbered="true" toc="default">
<name>Change Log</name>
<ul empty="true" spacing="normal">
<li>
<strong>RFC Editor's Note:</strong> Please remove this section prior t
o publication of a
final version of this document.</li>
</ul>
<t>Issue and pull request numbers are listed with a leading octothorp.</t>
<section anchor="since-draft-ietf-quic-tls-32" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-32</name>
<ul spacing="normal">
<li>Added final values for Initial key derivation, Retry authenticatio
n, and TLS
extension type for the QUIC Transport Parameters extension (#4431)
(#4431)</li>
<li>Corrected rules for handling of 0-RTT (#4393, #4394)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-31" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-31</name>
<ul spacing="normal">
<li>Packet protection limits are based on maximum-sized packets; impro
ved
analysis (#3701, #4175)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-30" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-30</name>
<ul spacing="normal">
<li>Add a new error code for AEAD_LIMIT_REACHED code to avoid conflict
(#4087,
#4088)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-29" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-29</name>
<ul spacing="normal">
<li>Updated limits on packet protection (#3788, #3789)</li>
<li>Allow for packet processing to continue while waiting for TLS to p
rovide
keys (#3821, #3874)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-28" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-28</name>
<ul spacing="normal">
<li>Defined limits on the number of packets that can be protected with
a single
key and limits on the number of packets that can fail authentication (#3619,
#3620)</li>
<li>Update Initial salt, Retry keys, and samples (#3711)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-27" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-27</name>
<ul spacing="normal">
<li>Allowed CONNECTION_CLOSE in any packet number space, with restrict
ions on
use of the application-specific variant (#3430, #3435, #3440)</li>
<li>Prohibit the use of the compatibility mode from TLS 1.3 (#3594, #3
595)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-26" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-26</name>
<ul spacing="normal">
<li>No changes</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-25" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-25</name>
<ul spacing="normal">
<li>No changes</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-24" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-24</name>
<ul spacing="normal">
<li>
<t>Rewrite key updates (#3050)
</t>
<ul spacing="normal">
<li>Allow but don't recommend deferring key updates (#2792, #3263)
</li>
<li>More completely define received behavior (#2791)</li>
<li>Define the label used with HKDF-Expand-Label (#3054)</li>
</ul>
</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-23" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-23</name>
<ul spacing="normal">
<li>
<t>Key update text update (#3050):
</t>
<ul spacing="normal">
<li>Recommend constant-time key replacement (#2792)</li>
<li>Provide explicit labels for key update key derivation (#3054)<
/li>
</ul>
</li>
<li>Allow first Initial from a client to span multiple packets (#2928,
#3045)</li>
<li>PING can be sent at any encryption level (#3034, #3035)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-22" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-22</name>
<ul spacing="normal">
<li>Update the salt used for Initial secrets (#2887, #2980)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-21" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-21</name>
<ul spacing="normal">
<li>No changes</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-20" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-20</name>
<ul spacing="normal">
<li>Mandate the use of the QUIC transport parameters extension (#2528,
#2560)</li>
<li>Define handshake completion and confirmation; define clearer rules
when it
encryption keys should be discarded (#2214, #2267, #2673)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-18" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-18</name>
<ul spacing="normal">
<li>Increased the set of permissible frames in 0-RTT (#2344, #2355)</l
i>
<li>Transport parameter extension is mandatory (#2528, #2560)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-17" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-17</name>
<ul spacing="normal">
<li>Endpoints discard initial keys as soon as handshake keys are avail
able (#1951,
#2045)</li>
<li>Use of ALPN or equivalent is mandatory (#2263, #2284)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-14" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-14</name>
<ul spacing="normal">
<li>Update the salt used for Initial secrets (#1970)</li>
<li>Clarify that TLS_AES_128_CCM_8_SHA256 isn't supported (#2019)</li>
<li>
<t>Change header protection
</t>
<ul spacing="normal">
<li>Sample from a fixed offset (#1575, #2030)</li>
<li>Cover part of the first byte, including the key phase (#1322,
#2006)</li>
</ul>
</li>
<li>
<t>TLS provides an AEAD and KDF function (#2046)
</t>
<ul spacing="normal">
<li>Clarify that the TLS KDF is used with TLS (#1997)</li>
<li>Change the labels for calculation of QUIC keys (#1845, #1971,
#1991)</li>
</ul>
</li>
<li>Initial keys are discarded once Handshake keys are available (#195
1, #2045)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-13" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-13</name>
<ul spacing="normal">
<li>Updated to TLS 1.3 final (#1660)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-12" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-12</name>
<ul spacing="normal">
<li>
<t>Changes to integration of the TLS handshake (#829, #1018, #1094,
#1165, #1190,
#1233, #1242, #1252, #1450)
</t>
<ul spacing="normal">
<li>The cryptographic handshake uses CRYPTO frames, not stream 0</
li>
<li>QUIC packet protection is used in place of TLS record protecti
on</li>
<li>Separate QUIC packet number spaces are used for the handshake<
/li>
<li>Changed Retry to be independent of the cryptographic handshake
</li>
<li>Limit the use of HelloRetryRequest to address TLS needs (like
key shares)</li>
</ul>
</li>
<li>Changed codepoint of TLS extension (#1395, #1402)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-11" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-11</name>
<ul spacing="normal">
<li>Encrypted packet numbers.</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-10" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-10</name>
<ul spacing="normal">
<li>No significant changes.</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-09" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-09</name>
<ul spacing="normal">
<li>Cleaned up key schedule and updated the salt used for handshake pa
cket
protection (#1077)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-08" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-08</name>
<ul spacing="normal">
<li>Specify value for max_early_data_size to enable 0-RTT (#942)</li>
<li>Update key derivation function (#1003, #1004)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-07" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-07</name>
<ul spacing="normal">
<li>Handshake errors can be reported with CONNECTION_CLOSE (#608, #891
)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-05" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-05</name>
<t>No significant changes.</t>
</section>
<section anchor="since-draft-ietf-quic-tls-04" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-04</name>
<ul spacing="normal">
<li>Update labels used in HKDF-Expand-Label to match TLS 1.3 (#642)</l
i>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-03" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-03</name>
<t>No significant changes.</t>
</section>
<section anchor="since-draft-ietf-quic-tls-02" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-02</name>
<ul spacing="normal">
<li>Updates to match changes in transport draft</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-01" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-01</name>
<ul spacing="normal">
<li>Use TLS alerts to signal TLS errors (#272, #374)</li>
<li>Require ClientHello to fit in a single packet (#338)</li>
<li>The second client handshake flight is now sent in the clear (#262,
#337)</li>
<li>The QUIC header is included as AEAD Associated Data (#226, #243, #
302)</li>
<li>Add interface necessary for client address validation (#275)</li>
<li>Define peer authentication (#140)</li>
<li>Require at least TLS 1.3 (#138)</li>
<li>Define transport parameters as a TLS extension (#122)</li>
<li>Define handling for protected packets before the handshake complet
es (#39)</li>
<li>Decouple QUIC version and ALPN (#12)</li>
</ul>
</section>
<section anchor="since-draft-ietf-quic-tls-00" numbered="true" toc="defaul
t">
<name>Since draft-ietf-quic-tls-00</name>
<ul spacing="normal">
<li>Changed bit used to signal key phase</li>
<li>Updated key phase markings during the handshake</li>
<li>Added TLS interface requirements section</li>
<li>Moved to use of TLS exporters for key derivation</li>
<li>Moved TLS error code definitions into this document</li>
</ul>
</section>
<section anchor="since-draft-thomson-quic-tls-01" numbered="true" toc="def
ault">
<name>Since draft-thomson-quic-tls-01</name>
<ul spacing="normal">
<li>Adopted as base for draft-ietf-quic-tls</li>
<li>Updated authors/editors list</li>
<li>Added status note</li>
</ul>
</section> </section>
</section> </section>
<section numbered="false" anchor="contributors" toc="default"> <section numbered="false" anchor="contributors" toc="default">
<name>Contributors</name> <name>Contributors</name>
<t>The IETF QUIC Working Group received an enormous amount of support from many <t>The IETF QUIC Working Group received an enormous amount of support from many
people. The following people provided substantive contributions to this people. The following people provided substantive contributions to this
document:</t> document:</t>
<ul spacing="normal"> <ul spacing="compact">
<li>Adam Langley</li>
<li>Alessandro Ghedini</li>
<li>Christian Huitema</li>
<li>Christopher Wood</li>
<li>David Schinazi</li>
<li>Dragana Damjanovic</li>
<li>Eric Rescorla</li>
<li>Felix Guenther</li>
<li>Ian Swett</li>
<li>Jana Iyengar</li>
<li> <li>
<t> <contact asciiFullname="Kazuho Oku" fullname="奥 一穂"/> <t><contact fullname="Adam Langley"/></t>
</t>
</li> </li>
<li>Marten Seemann</li>
<li>Martin Duke</li>
<li>Mike Bishop</li>
<li> <li>
<t> <contact fullname="Mikkel Fahnøe Jørgensen"/> <t><contact fullname="Alessandro Ghedini"/></t>
</t> </li>
<li>
<t><contact fullname="Christian Huitema"/></t>
</li>
<li>
<t><contact fullname="Christopher Wood"/></t>
</li>
<li>
<t><contact fullname="David Schinazi"/></t>
</li>
<li>
<t><contact fullname="Dragana Damjanovic"/></t>
</li>
<li>
<t><contact fullname="Eric Rescorla"/></t>
</li>
<li>
<t><contact fullname="Felix Günther"/></t>
</li>
<li>
<t><contact fullname="Ian Swett"/></t>
</li>
<li>
<t><contact fullname="Jana Iyengar"/></t>
</li>
<li>
<t><contact asciiFullname="Kazuho Oku" fullname="奥 一穂"/></t>
</li>
<li>
<t><contact fullname="Marten Seemann"/></t>
</li>
<li>
<t><contact fullname="Martin Duke"/></t>
</li>
<li>
<t><contact fullname="Mike Bishop"/></t>
</li>
<li>
<t><contact fullname="Mikkel Fahnøe Jørgensen"/></t>
</li>
<li>
<t><contact fullname="Nick Banks"/></t>
</li>
<li>
<t><contact fullname="Nick Harper"/></t>
</li>
<li>
<t><contact fullname="Roberto Peon"/></t>
</li>
<li>
<t><contact fullname="Rui Paulo"/></t>
</li>
<li>
<t><contact fullname="Ryan Hamilton"/></t>
</li>
<li>
<t><contact fullname="Victor Vasiliev"/></t>
</li> </li>
<li>Nick Banks</li>
<li>Nick Harper</li>
<li>Roberto Peon</li>
<li>Rui Paulo</li>
<li>Ryan Hamilton</li>
<li>Victor Vasiliev</li>
</ul> </ul>
</section> </section>
</back> </back>
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