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<rfc category="std" docName="draft-ietf-dtn-bpsec-27" ipr="trust200902"
obsoletes="" submissionType="IETF" updates="" xml:lang="en">
<front>
<title>Bundle Protocol Security Specification</title>
<author fullname="Edward J. Birrane, III" initials="E.J." <rfc xmlns:xi="http://www.w3.org/2001/XInclude" docName="draft-ietf-dtn-bpsec-27
surname="Birrane"> " number="9172" ipr="trust200902" obsoletes="" submissionType="IETF" category="s
<organization abbrev="JHU/APL">The Johns Hopkins University Applied td"
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<front>
<title>Bundle Protocol Security (BPSec)</title>
<seriesInfo name="RFC" value="9172"/>
<author fullname="Edward J. Birrane, III" initials="E" surname="Birrane, III
">
<organization abbrev="JHU/APL">The Johns Hopkins University Applied
Physics Laboratory</organization> Physics Laboratory</organization>
<address> <address>
<postal> <postal>
<street>11100 Johns Hopkins Rd.</street> <street>11100 Johns Hopkins Rd.</street>
<city>Laurel</city> <city>Laurel</city>
<region>MD</region> <region>MD</region>
<code>20723</code> <code>20723</code>
<country>US</country> <country>United States of America</country>
</postal> </postal>
<phone>+1 443 778 7423</phone> <phone>+1 443 778 7423</phone>
<email>Edward.Birrane@jhuapl.edu</email> <email>Edward.Birrane@jhuapl.edu</email>
</address> </address>
</author> </author>
<author fullname="Kenneth McKeever" initials="K" surname="McKeever">
<author fullname="Kenneth McKeever" initials="K.R." <organization abbrev="JHU/APL">The Johns Hopkins University Applied
surname="McKeever">
<organization abbrev="JHU/APL">The Johns Hopkins University Applied
Physics Laboratory</organization> Physics Laboratory</organization>
<address> <address>
<postal> <postal>
<street>11100 Johns Hopkins Rd.</street> <street>11100 Johns Hopkins Rd.</street>
<city>Laurel</city> <city>Laurel</city>
<region>MD</region> <region>MD</region>
<code>20723</code> <code>20723</code>
<country>US</country> <country>United States of America</country>
</postal> </postal>
<phone>+1 443 778 2237</phone> <phone>+1 443 778 2237</phone>
<email>Ken.McKeever@jhuapl.edu</email> <email>Ken.McKeever@jhuapl.edu</email>
</address> </address>
</author> </author>
<date month="January" year="2022"/>
<date month="February" day="15" year="2021"/>
<!-- Meta-data -->
<area>General</area> <area>General</area>
<workgroup>Delay-Tolerant Networking</workgroup>
<workgroup>Delay-Tolerant Networking</workgroup> <keyword>security</keyword>
<keyword>bundle</keyword>
<keyword>security</keyword> <keyword>integrity</keyword>
<keyword>bundle</keyword> <keyword>confidentiality</keyword>
<keyword>integrity</keyword> <abstract>
<keyword>confidentiality</keyword> <t>
<abstract>
<t>
This document defines a security protocol providing data This document defines a security protocol providing data
integrity and confidentiality services for the Bundle Protocol. integrity and confidentiality services for the Bundle Protocol (BP).
</t> </t>
</abstract>
</abstract> </front>
</front> <middle>
<section anchor="intro" toc="default" numbered="true">
<middle> <name>Introduction</name>
<t>
<section anchor="intro" title="Introduction" toc="default">
<t>
This document defines security features for the Bundle Protocol This document defines security features for the Bundle Protocol
(BP) <xref target="I-D.ietf-dtn-bpbis"/> and is intended for use (BP) <xref target="RFC9171" format="default"/> and is intended for use
in Delay Tolerant Networks (DTNs) to provide security in Delay-Tolerant Networking (DTN) to provide security
services between a security source and a security acceptor. When the services between a security source and a security acceptor. When the
security source is the bundle source and when the security acceptor is security source is the bundle source and the security acceptor is
the bundle destination, the security service provides end-to-end the bundle destination, the security service provides end-to-end
protection. protection.
</t> </t>
<t>
<t> The Bundle Protocol specification <xref target="RFC9171" format="default"/
The Bundle Protocol specification <xref target="I-D.ietf-dtn-bpbis"/> >
defines DTN as referring to "a networking architecture providing defines DTN as referring to "a network architecture providing
communications in and/or through highly stressed environments" communications in and/or through highly stressed environments"
where "BP may be viewed as sitting at the application layer of some where "BP may be viewed as sitting at the application layer of some
number of constituent networks, forming a store-carry-forward number of constituent networks, forming a store-carry-forward
overlay network". The term "stressed" environment refers to multiple overlay network". The phrase "stressed environment" refers to multiple
challenging conditions including intermittent connectivity, large challenging conditions including intermittent connectivity, large
and/or variable delays, asymmetric data rates, and high bit error and/or variable delays, asymmetric data rates, and high bit error
rates. rates.
</t> </t>
<t>
<t> It should be presumed that the BP will be deployed in an untrusted
It should be presumed that the BP will be deployed such that the network c network, which poses the usual security challenges
annot related to confidentiality and integrity. However, the stressed nature of the
be trusted, posing the usual security challenges related to BP
confidentiality and integrity. However, the stressed nature of the BP
operating environment imposes unique conditions where usual transport operating environment imposes unique conditions where usual transport
security mechanisms may not be sufficient. For example, the security mechanisms may not be sufficient. For example, the
store-carry-forward nature of the network may require protecting store-carry-forward nature of the network may require protecting
data at rest, preventing unauthorized consumption of critical data at rest, preventing unauthorized consumption of critical
resources such as storage space, and operating without regular resources such as storage space, and operating without regular
contact with a centralized security oracle (such as a certificate contact with a centralized security oracle (such as a certificate
authority). authority).
</t> </t>
<t>
An end-to-end security service is needed that operates in all of the
environments where the BP operates.
</t>
<section anchor="sup_sec_svc" title="Supported Security Services">
<t> <t>
An end-to-end security service that operates in all of the
environments where the BP operates is needed.
</t>
<section anchor="sup_sec_svc" numbered="true" toc="default">
<name>Supported Security Services</name>
<t>
BPSec provides integrity and confidentiality BPSec provides integrity and confidentiality
services for BP bundles, as defined in this section. services for BP bundles, as defined in this section.
</t> </t>
<t> <t>
Integrity services ensure that changes to target data Integrity services ensure that changes to target data
within a bundle can be discovered. Data changes within a bundle can be discovered. Data changes
may be caused by processing errors, environmental conditions, may be caused by processing errors, environmental conditions,
or intentional manipulation. In the context of BPSec, integrity or intentional manipulation. In the context of BPSec, integrity
services apply to plain text in the bundle. services apply to plaintext in the bundle.
</t> </t>
<t>
<t>
Confidentiality services ensure that target data is unintelligible Confidentiality services ensure that target data is unintelligible
to nodes in the DTN, except for authorized nodes possessing to nodes in DTN, except for authorized nodes possessing
special information. This generally means producing cipher text from special information. Generally, this means producing ciphertext from
plain text and generating authentication information for that plaintext and generating authentication information for that
cipher text. Confidentiality, in this context, applies ciphertext. In this context, confidentiality applies
to the contents of target data and does not extend to hiding to the contents of target data and does not extend to hiding
the fact that confidentiality exists in the bundle. the fact that confidentiality exists in the bundle.
</t> </t>
<t>
<t>
NOTE: Hop-by-hop authentication is NOT a supported security service NOTE: Hop-by-hop authentication is NOT a supported security service
in this specification, for two reasons. in this specification, for two reasons:
<list style="numbers"> </t>
<t> <ol spacing="normal" type="1"><li>
The term "hop-by-hop" is ambiguous in a BP overlay, as nodes The term "hop-by-hop" is ambiguous in a BP overlay, as nodes
that are adjacent in the overlay may not be adjacent in that are adjacent in the overlay may not be adjacent in
physical connectivity. This condition is difficult or physical connectivity. This condition is difficult or
impossible to detect and therefore hop-by-hop authentication is impossible to detect; therefore, hop-by-hop authentication is
difficult or impossible to enforce. difficult or impossible to enforce.
</t> </li>
<t> <li>
Hop-by-hop authentication cannot be deployed in a network if adja cent Hop-by-hop authentication cannot be deployed in a network if adja cent
nodes in the network have incompatible security capabilities. nodes in the network have incompatible security capabilities.
</t> </li>
</list> </ol>
</t> </section>
</section> <section numbered="true" toc="default">
<name>Specification Scope</name>
<section title="Specification Scope"> <t>
<t>
This document defines the security services provided by the BPSec. This document defines the security services provided by the BPSec.
This includes the data specification for representing these This includes the data specification for representing these
services as BP extension blocks, and the rules for adding, services as BP extension blocks and the rules for adding,
removing, and processing these blocks at various points during removing, and processing these blocks at various points during
the bundle's traversal of the DTN. the bundle's traversal of a delay-tolerant network.
</t> </t>
<t>
<t>
BPSec addresses only the security of data traveling over the BPSec addresses only the security of data traveling over the
DTN, not the underlying DTN itself. Furthermore, while the BPSec DTN, not the underlying DTN itself. Furthermore, while the BPSec
protocol can provide security-at-rest in a store-carry-forward protocol can provide security-at-rest in a store-carry-forward
network, it does not address threats which share computing resources network, it does not address threats that share computing resources
with the DTN and/or BPSec software implementations. These threats with the DTN and/or BPSec software implementations. These threats
may be malicious software or compromised libraries which intend may be malicious software or compromised libraries that intend
to intercept data or recover cryptographic material. Here, it is to intercept data or recover cryptographic material. Here, it is
the responsibility of the BPSec implementer to ensure that any the responsibility of the BPSec implementer to ensure that any
cryptographic material, including shared secret or private keys, cryptographic material, including shared secrets or private keys,
is protected against access within both memory and storage devices. is protected against access within both memory and storage devices.
</t> </t>
<t>
<t> Completely trusted networks are extremely uncommon. Among
Completely trusted networks are extremely untrusted networks, different networking conditions and
uncommon. Amongst untrusted networks, different networking conditions a operational considerations require security mechanisms of
nd varying strengths.
operational considerations require varying strengths of security Mandating a single security context, which is a set of assumptions,
mechanism. Mandating a single security context may result in too much s algorithms, configurations, and policies used to implement security
ecurity services, may result in too much security for some networks and too
for some networks and too little security in others. It is expected tha little security in others. Default security contexts are
t separate defined in <xref target="RFC9173" format="default"/> to provide basic securit
documents define different security contexts for use in different netwo y services for
rks. interoperability testing and for operational use on the terrestrial
A set of default security contexts are defined in (<xref target="I-D.ie Internet. It is expected that separate documents will define
tf-dtn-bpsec-default-sc"/>) different security contexts for use in different networks.
and provide basic security services for interoperability </t>
testing and for operational use on the terrestrial Internet. <t>
</t>
<t>
This specification addresses neither the fitness of This specification addresses neither the fitness of
externally-defined cryptographic methods nor the security of externally defined cryptographic methods nor the security of
their implementation. their implementation.
</t> </t>
<t>
<t>
This specification does not address the implementation of This specification does not address the implementation of
security policy and does not provide a security policy for the security policies and does not provide a security policy for the
BPSec. Similar to cipher suites, security policies are based on BPSec. Similar to cipher suites, security policies are based on
the nature and capabilities of individual networks and network the nature and capabilities of individual networks and network
operational concepts. This specification does provide policy operational concepts. This specification does provide policy considerat
considerations when building a security policy. ions that
</t> can be taken into account when building a security policy.
</t>
<t> <t>
With the exception of the Bundle Protocol, this specification With the exception of the Bundle Protocol, this specification
does not address how to combine the BPSec security blocks with does not address how to combine the BPSec security blocks with
other protocols, other BP extension blocks, or other best other protocols, other BP extension blocks, or other best
practices to achieve security in any particular network practices to achieve security in any particular network
implementation. implementation.
</t> </t>
</section>
</section> <section anchor="reldoc" toc="default" numbered="true">
<name>Related Documents</name>
<section anchor="reldoc" title="Related Documents" toc="default"> <t>
<t>
This document is best read and understood within the context of This document is best read and understood within the context of
the following other DTN documents: the following other DTN documents:
</t> </t>
<ul>
<t> <li>"<xref target="RFC4838" format="title"/>" <xref target="RFC4838" fo
"Delay-Tolerant Networking Architecture" <xref target="RFC4838"/> rmat="default"/>
defines the architecture for DTNs and identifies certain security defines the architecture for DTN and identifies certain security
assumptions made by existing Internet protocols that are not valid in assumptions made by existing Internet protocols that are not valid in
a DTN. DTN.
</t> </li>
<li>
<t> "<xref target="RFC9171" format="title"/>" <xref target="RFC9171" format
The Bundle Protocol <xref target="I-D.ietf-dtn-bpbis"/> defines ="default"/> defines
the format and processing of bundles, defines the extension the format and processing of bundles, the extension
block format used to represent BPSec security blocks, and defines block format used to represent BPSec security blocks, and
the canonical block structure used by this specification. the canonical block structure used by this specification.
</t> </li>
<li>
<t> "<xref target="RFC8949" format="title"/>" <xref target="RFC8949" format
The Concise Binary Object Representation (CBOR) format <xref target="RF ="default"/>
C8949"/>
defines a data format that allows for small code size, fairly small defines a data format that allows for small code size, fairly small
message size, and extensibility without version negotiation. The message size, and extensibility without version negotiation. The
block-specific-data associated with BPSec security blocks are encoded block-type-specific data associated with BPSec security blocks is encod ed
in this data format. in this data format.
</t> </li>
<li>
<t> "<xref target="RFC6257" format="title"/>" <xref target="RFC6257" format
The Bundle Security Protocol <xref target="RFC6257"/> and ="default"/>
Streamlined Bundle Security Protocol introduces the
<xref target="I-D.birrane-dtn-sbsp"/> documents introduced the concept of using BP extension blocks for security services
concepts of using BP extension blocks for security services in DTN. BPSec is a continuation and refinement of this
in a DTN. The BPSec is a continuation and refinement of these document.
documents. </li>
</t> </ul>
</section> </section>
<section anchor="term" toc="default" numbered="true">
<section anchor="term" title="Terminology" toc="default"> <name>Terminology</name>
<t> <t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL 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
"MAY", and "OPTIONAL" in this document are to be interpreted as NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<b
described in BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> w cp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
hen, and only when, they "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document ar
e to be interpreted as
described in BCP&nbsp;14 <xref target="RFC2119" format="default"/> <xre
f target="RFC8174" format="default"/> when, and only when, they
appear in all capitals, as shown here. appear in all capitals, as shown here.
</t> </t>
<t>
<t> This section defines terminology that either is unique to the BPSec or
This section defines terminology either unique to the BPSec or is necessary for understanding the concepts defined in
otherwise necessary for understanding the concepts defined in
this specification. this specification.
<list style="symbols"> </t>
<dl spacing="normal">
<t> <dt>Bundle Destination:</dt><dd>the Bundle Protocol Agent (BPA)
Bundle Destination - the node which receives a bundle and deliver that receives a bundle and delivers the payload of the bundle
s to an Application Agent. Also, an endpoint comprising the
the payload of the bundle to an application. Also, the Node ID of node(s) at which the bundle is to be delivered. The bundle
the Bundle Protocol Agent (BPA) receiving the bundle. The bundle destination acts as the security acceptor for every security
destination acts as target in every security block in every bundle it receives.
the security acceptor for every security target in every </dd>
security block in every bundle it receives. <dt>Bundle Source:</dt><dd>the BPA that originates a
</t> bundle. Also, any node ID of the node of which the BPA is a
component.
<t> </dd>
Bundle Source - the node which originates a bundle. Also, the <dt>Cipher Suite:</dt><dd>a set of one or more algorithms
Node ID of the BPA originating the bundle. providing integrity and/or confidentiality services. Cipher
</t> suites may define user parameters (e.g., secret keys to
use), but they do not provide values for those parameters.
<t> </dd>
Cipher Suite - a set of one or more algorithms providing <dt>Forwarder:</dt><dd>any BPA that transmits a bundle in
integrity and/or confidentiality services. Cipher suites may defi DTN. Also, any node ID of the node of which the BPA that
ne sent the bundle on its most recent hop is a component.
user parameters (e.g. secret keys to use) but do not provide valu </dd>
es for <dt>Intermediate Receiver, Waypoint, or Next
those parameters. Hop:</dt><dd>any BPA that receives a bundle from a
</t> forwarder that is not the bundle destination. Also, any node
ID of the node of which the BPA is a component.
<t> </dd>
Forwarder - any node that transmits a bundle in the DTN. <dt>Path:</dt><dd>the ordered sequence of nodes through
Also, the Node ID of the BPA that sent which a bundle passes on its way from source to
the bundle on its most recent hop. destination. The path is not necessarily known in advance by
</t> the bundle or any BPAs in DTN.
</dd>
<t> <dt>Security Acceptor:</dt><dd>a BPA that processes
Intermediate Receiver, Waypoint, or Next Hop - any node and dispositions one or more security blocks in a bundle.
that receives a bundle from a Forwarder that is not the Security acceptors act as the endpoint of a security service
Bundle Destination. Also, the Node ID of the BPA at any such node represented in a security block. They remove the security
. blocks they act upon as part of processing and disposition.
</t> Also, any node ID of the node of which the BPA is a component.
</dd>
<t> <dt>Security Block:</dt><dd>a BPSec extension block in a
Path - the ordered sequence of nodes through which a bundle bundle.
passes on its way from Source to Destination. The path is not </dd>
necessarily known in advance by the bundle or any BPAs in the <dt>Security Context:</dt><dd>the set of assumptions,
DTN. algorithms, configurations, and policies used to implement
</t> security services.
</dd>
<t> <dt>Security Operation:</dt><dd>the application of a given
Security Acceptor - a bundle node that processes and dispositions security service to a security target, notated as
one or more OP(security service, security target). For example,
security blocks in a bundle. Security acceptors act as the endpoi OP(bcb-confidentiality, payload). Every security operation
nt of a security in a bundle <bcp14>MUST</bcp14> be unique, meaning that a
service represented in a security block. They remove the security given security service can only be applied to a security
blocks they act target once in a bundle. A security operation is implemented
upon as part of processing and disposition. Also, the Node ID of by a security block.
that node. </dd>
</t> <dt>Security Service:</dt><dd>a process that gives some
protection to a security target. For example, this
<t> specification defines security services for plaintext
Security Block - a BPSec extension block in a bundle. integrity (bib-integrity) and authenticated plaintext
</t> confidentiality with additional authenticated data
(bcb-confidentiality).
<t> </dd>
Security Context - the set of assumptions, algorithms, <dt>Security Source:</dt><dd>a BPA that adds a
configurations and policies used to implement security services. security block to a bundle. Also, any node ID of the node
</t> of which the BPA is a component.
</dd>
<t> <dt>Security Target:</dt><dd>the block within a bundle that
Security Operation - the application of a given security service receives a security service as part of a security operation.
to a security target, notated as OP(security service, </dd>
security target). For example, OP(bcb-confidentiality, payload). <dt>Security Verifier:</dt><dd>a BPA that verifies
Every security operation in a bundle MUST be unique, meaning the data integrity of one or more security blocks in a bundle.
that a given security service can only be applied to a security Unlike security acceptors, security verifiers do not act as
target once in a bundle. A security operation is the endpoint of a security service, and they do not remove
implemented by a security block. verified security blocks. Also, any node ID of the node of
</t> which the BPA is a component.
</dd>
<t> </dl>
Security Service - a process that gives some </section>
protection to a security target. For example, this specification </section>
defines security <section numbered="true" toc="default">
services for plain text integrity (bib-integrity), and authentica <name>Design Decisions</name>
ted <t>
plain text confidentiality with additional authenticated data (bc The application of security services in DTN is a complex endeavor
b-confidentiality).
</t>
<t>
Security Source - a bundle node that adds a security block to a
bundle. Also, the Node ID of that node.
</t>
<t>
Security Target - the block within a bundle that
receives a security service as part of a security operation.
</t>
<t>
Security Verifier - a bundle node that verifies the correctness o
f
one or more security blocks in a bundle. Unlike security acceptor
s,
security verifiers do not act as the endpoint of a security servi
ce and do
not remove verified security blocks. Also, the Node ID of that no
de.
</t>
</list>
</t>
</section>
</section>
<section title="Design Decisions">
<t>
The application of security services in a DTN is a complex endeavor
that must consider physical properties of the network (such as connectivit y and that must consider physical properties of the network (such as connectivit y and
propagation times), policies at propagation times), policies at
each node, application security requirements, and current and future each node, application security requirements, and current and future
threat environments. This section threat environments. This section
identifies those desirable properties that guide design decisions for identifies those desirable properties that guide design decisions for
this specification and are necessary for understanding the format and this specification and that are necessary for understanding the format and
behavior of the BPSec protocol. behavior of the BPSec protocol.
</t> </t>
<section numbered="true" toc="default">
<section title="Block-Level Granularity"> <name>Block-Level Granularity</name>
<t>
<t>
Security services within this specification must allow different Security services within this specification must allow different
blocks within a bundle to have different security services blocks within a bundle to have different security services
applied to them. applied to them.
</t> </t>
<t>
<t>
Blocks within a bundle represent different types of information. The Blocks within a bundle represent different types of information. The
primary block contains identification and routing information. The primary block contains identification and routing information. The
payload block carries application data. Extension blocks carry a payload block carries application data. Extension blocks carry a
variety of data that may augment or annotate the payload, or variety of data that may augment or annotate the payload or that
otherwise provide information necessary for the proper processing otherwise provide information necessary for the proper processing
of a bundle along a path. Therefore, applying a single level and of a bundle along a path. Therefore, applying a single level and
type of security across an entire bundle type of security across an entire bundle
fails to recognize that blocks in a bundle represent different fails to recognize that blocks in a bundle represent different
types of information with different security needs. types of information with different security needs.
</t> </t>
<t>
<t>
For example, a payload block might be encrypted to For example, a payload block might be encrypted to
protect its contents and an extension block containing protect its contents and an extension block containing
summary information related to the payload might be integrity summary information related to the payload might be integrity
signed but unencrypted to provide waypoints access signed but unencrypted to provide waypoints access
to payload-related data without providing access to the payload. to payload-related data without providing access to the payload.
</t> </t>
</section>
</section> <section numbered="true" toc="default">
<name>Multiple Security Sources</name>
<section title="Multiple Security Sources"> <t>
A bundle can have multiple security blocks, and these blocks can
<t> have different security sources. BPSec implementations <bcp14>MUST
A bundle can have multiple security blocks and these blocks can NOT</bcp14> assume that all blocks in a bundle have the same security
have different security sources. BPSec implementations MUST
NOT assume that all blocks in a bundle have the same security
operations applied to them. operations applied to them.
</t> </t>
<t>
<t>
The Bundle Protocol allows extension blocks to be added to a bundle The Bundle Protocol allows extension blocks to be added to a bundle
at any time during its existence in the DTN. When a waypoint at any time during its existence in DTN. When a waypoint
adds a new extension block to a bundle, that extension block adds a new extension block to a bundle, that extension block
MAY have security services applied to it by that waypoint. Similarly, <bcp14>MAY</bcp14> have security services applied to it by that waypoin
a waypoint MAY add a security service to an existing t. Similarly,
a waypoint <bcp14>MAY</bcp14> add a security service to an existing
block, consistent with its security policy. block, consistent with its security policy.
</t> </t>
<t>
<t>
When a waypoint adds a security service to the bundle, the waypoint When a waypoint adds a security service to the bundle, the waypoint
is the security source for that service. The security block(s) is the security source for that service. The security block(s)
which represent that service in the bundle may need to record this that represent that service in the bundle may need to record this
security source as the bundle destination might need this information security source, as the bundle destination might need this information
for processing. for processing.
</t> </t>
<t> <t>
For example, a bundle source may choose to apply an integrity service For example, a bundle source may choose to apply an integrity service
to its plain text payload. Later a waypoint node, representing a to its plaintext payload. Later a waypoint node, representing a
gateway to another portion of the DTN, may receive the bundle and gateway to another portion of the delay-tolerant network, may receive t
he bundle and
choose to apply a confidentiality service. In this case, the choose to apply a confidentiality service. In this case, the
integrity security source is the bundle source and the integrity security source is the bundle source and the
confidentiality security source is the waypoint node. confidentiality security source is the waypoint node.
</t> </t>
<t> <t>
In cases where the security source and security acceptor are not the In cases where the security source and security acceptor are not the
bundle source and bundle destination, it is possible that the bundle bundle source and bundle destination, respectively, it is possible that the bundle
will reach the bundle destination prior to reaching a security will reach the bundle destination prior to reaching a security
acceptor. In cases where this may be a practical problem, it is acceptor. In cases where this may be a practical problem, it is
recommended that solutions such as bundle encapsulation can be recommended that solutions such as bundle encapsulation be
used to ensure that a bundle be delivered to a security acceptor used to ensure that a bundle be delivered to a security acceptor
prior to being delivered to the bundle destination. Generally, prior to being delivered to the bundle destination. Generally,
if a bundle reaches a waypoint that has the appropriate configuration if a bundle reaches a waypoint that has the appropriate configuration
and policy to act as a security acceptor for a security service in and policy to act as a security acceptor for a security service in
the bundle, then the waypoint should act as that security acceptor. the bundle, then the waypoint should act as that security acceptor.
</t> </t>
</section>
</section> <section numbered="true" toc="default">
<name>Mixed Security Policy</name>
<section title="Mixed Security Policy"> <t>
The security policy enforced by nodes in the delay-tolerant network may
<t> differ.
The security policy enforced by nodes in the DTN may differ. </t>
</t> <t>
Some waypoints will have security policies that require the waypoint
<t> to evaluate security services even if the waypoint is neither the
Some waypoints will have security policies that require bundle destination nor the final intended acceptor of the service.
evaluating security services even if they are not the bundle
destination or the final intended acceptor of the service.
For example, a waypoint could choose to For example, a waypoint could choose to
verify an integrity service even though the waypoint is not verify an integrity service even though the waypoint is not
the bundle destination and the integrity service will be needed the bundle destination and the integrity service will be needed
by other nodes along the bundle's path. by other nodes along the bundle's path.
</t> </t>
<t>
<t>
Some waypoints will determine, through policy, that they are the Some waypoints will determine, through policy, that they are the
intended recipient of the security service and terminate the intended recipient of the security service and will terminate the
security service in the bundle. For example, a gateway node could security service in the bundle. For example, a gateway node could
determine that, even though it is not the destination of the bundle, determine that, even though it is not the destination of the bundle,
it should verify and remove a particular integrity service or it should verify and remove a particular integrity service or
attempt to decrypt a confidentiality service, before forwarding the attempt to decrypt a confidentiality service, before forwarding the
bundle along its path. bundle along its path.
</t> </t>
<t>
<t>
Some waypoints could understand security blocks but refuse to Some waypoints could understand security blocks but refuse to
process them unless they are the bundle destination. process them unless they are the bundle destination.
</t> </t>
</section>
</section> <section numbered="true" toc="default">
<name>User-Defined Security Contexts</name>
<section title="User-Defined Security Contexts"> <t>
<t> A security context is the set of assumptions, algorithms, configuration
A security context is the union of security algorithms (cipher s,
suites), policies associated with the use of those algorithms, and and policies used to implement security services. Different contexts may s
configuration values. Different contexts may specify different pecify different
algorithms, different polices, or different configuration values used algorithms, different polices, or different configuration values used
in the implementation of their security services. BPSec provides in the implementation of their security services. BPSec provides
a mechanism to define security contexts. Users may select from a mechanism to define security contexts. Users may select from
registered security contexts and customize those contexts through registered security contexts and customize those contexts through
security context parameters. security context parameters.
</t> </t>
<t> <t>
For example, some users might prefer a For example, some users might prefer a
SHA2 hash function for integrity whereas other users might prefer a SHA2 hash function for integrity, whereas other users might prefer a
SHA3 hash function. Providing either separate security contexts or a si ngle, SHA3 hash function. Providing either separate security contexts or a si ngle,
parameterized security context allows users flexibility in applying parameterized security context allows users flexibility in applying
the desired cipher suite, policy, and configuration when populating the desired cipher suite, policy, and configuration when populating
a security block. a security block.
</t> </t>
</section> </section>
<section numbered="true" toc="default">
<section title="Deterministic Processing"> <name>Deterministic Processing</name>
<t> <t>
Whenever a node determines that it must process more than one Whenever a node determines that it must process more than one
security block in a received bundle (either because the policy security block in a received bundle (either because the policy
at a waypoint states that it should process security blocks or at a waypoint states that it should process security blocks or
because the node is the bundle destination) the order in which because the node is the bundle destination), the order in which
security blocks are processed must be deterministic. All nodes security blocks are processed must be deterministic. All nodes
must impose this same deterministic processing order for all must impose this same deterministic processing order for all
security blocks. This specification provides security blocks. This specification provides
determinism in the application and evaluation of security determinism in the application and evaluation of security
services, even when doing so results in a loss of flexibility. services, even when doing so results in a loss of flexibility.
</t> </t>
</section> </section>
</section>
</section> <section anchor="sec_blocks" numbered="true" toc="default">
<name>Security Blocks</name>
<section anchor="sec_blocks" title="Security Blocks"> <section anchor="sec_blocks_def" numbered="true" toc="default">
<name>Block Definitions</name>
<section anchor="sec_blocks_def" title="Block Definitions"> <t>
<t>
This specification defines two types of security block: the Block This specification defines two types of security block: the Block
Integrity Block (BIB) and the Block Confidentiality Block (BCB). Integrity Block (BIB) and the Block Confidentiality Block (BCB).
<list> </t>
<t> <ul spacing="normal">
The BIB is used to ensure the integrity of its plain text <li>
security target(s). The integrity information in the BIB MAY be The BIB is used to ensure the integrity of its plaintext
security target(s). The integrity information in the BIB <bcp14>M
AY</bcp14> be
verified by any node along the bundle path from the BIB verified by any node along the bundle path from the BIB
security source to the bundle destination. Waypoints add or remov e BIBs from bundles in accordance with security source to the bundle destination. Waypoints add or remov e BIBs from bundles in accordance with
their security policy. BIBs are never used for integrity protecti on their security policy. BIBs are never used for integrity protecti on
of the cipher text provided by a BCB. Because security policy at of the ciphertext provided by a BCB. Because security policy at
BPSec nodes may differ regarding integrity verification, BIBs do not BPSec nodes may differ regarding integrity verification, BIBs do not
guarantee hop-by-hop authentication, as discussed in <xref target guarantee hop-by-hop authentication, as discussed in <xref target
="sup_sec_svc"/>. ="sup_sec_svc" format="default"/>.
</t> </li>
<li>
<t> The BCB indicates that the security target or targets have been
The BCB indicates that the security target(s) have been
encrypted at the BCB security source in order to protect their encrypted at the BCB security source in order to protect their
content while in transit. The BCB is decrypted by security accept or content while in transit. As a matter of security policy, the BCB is decrypted by security acceptor
nodes in the network, up to and including the bundle nodes in the network, up to and including the bundle
destination, as a matter of security policy. BCBs additionally destination. BCBs additionally
provide integrity protection mechanisms for the cipher text they provide integrity-protection mechanisms for the ciphertext they
generate. generate.
</t> </li>
</list> </ul>
</t> </section>
</section> <section anchor="sec_blocks_uni" toc="default" numbered="true">
<name>Uniqueness</name>
<section anchor="sec_blocks_uni" title="Uniqueness" toc="default"> <t>
Security operations in a bundle <bcp14>MUST</bcp14> be unique; the same
<t> security
Security operations in a bundle MUST be unique; the same security service <bcp14>MUST NOT</bcp14> be applied to a security target more th
service MUST NOT be applied to a security target more than once in a an once in a
bundle. Since a security operation is represented by a security bundle. Since a security operation is represented by a security
block, this means that multiple security blocks of the same type cannot block, this means that multiple security blocks of the same type cannot
share the same security targets. A new security block MUST NOT be added share the same security targets. A new security block <bcp14>MUST NOT</
to a bundle if a pre-existing security block of the same type is bcp14> be added
to a bundle if a preexisting security block of the same type is
already defined for the security target of the new security block. already defined for the security target of the new security block.
</t> </t>
<t>
<t>
This uniqueness requirement ensures that there is no ambiguity related This uniqueness requirement ensures that there is no ambiguity related
to the order in which security blocks are processed or how security pol icy to the order in which security blocks are processed or how security pol icy
can be specified to require certain security services be present in a can be specified to require certain security services be present in a
bundle. bundle.
</t> </t>
<t>
<t>
Using the notation OP(service, target), several examples illustrate Using the notation OP(service, target), several examples illustrate
this uniqueness requirement. this uniqueness requirement.
<list style="symbols"> </t>
<t> <dl spacing="normal">
Signing the payload twice: The two operations OP(bib-integrity, <dt>Signing the payload twice:</dt><dd>The two operations OP(bib-integ
payload) and OP(bib-integrity, payload) are redundant and MUST NO rity,
T payload) and OP(bib-integrity, payload) are redundant and <bcp14>
MUST NOT</bcp14>
both be present in the same bundle at the same time. both be present in the same bundle at the same time.
</t> </dd>
<dt>Signing different blocks:</dt><dd>The two operations
<t> OP(bib-integrity, payload) and OP(bib-integrity,
Signing different blocks: The two operations OP(bib-integrity, extension_block_1) are not redundant and both may be present
payload) and OP(bib-integrity, extension_block_1) are not redunda in the same bundle at the same time. Similarly, the two
nt operations OP(bib-integrity, extension_block_1) and
and both may be present in the same bundle at the same time. OP(bib-integrity, extension_block_2) are also not redundant
Similarly, the two operations OP(bib-integrity, extension_block_1 and may both be present in the bundle at the same time.
) </dd>
and OP(bib-integrity, extension_block_2) are also not redundant a <dt>Different services on same block:</dt><dd>The two
nd operations OP(bib-integrity, payload) and
may both be present in the bundle at the same time. OP(bcb-confidentiality, payload) are not inherently
</t> redundant and may both be present in the bundle at the same
<t> time, pursuant to other processing rules in this
Different Services on same block: The two operations specification.
OP(bib-integrity, payload) and OP(bcb-confidentiality, payload) a </dd>
re not <dt>Different services from different block
inherently redundant and may both be present in the bundle at types:</dt><dd>The notation OP(service, target) refers
the same time, pursuant to other processing rules in this specifically to a security block, as the security block is
specification. the embodiment of a security service applied to a security
</t> target in a bundle. Were some Other Security Block (OSB) to
<t> be defined providing an integrity service, then the
Different services from different block types: The notation operations OP(bib-integrity, target) and OP(osb-integrity,
OP(service, target) refers specifically to a security block, as t target) <bcp14>MAY</bcp14> both be present in the same
he bundle if so allowed by the definition of the OSB, as
security block is the embodiment of a security service applied to discussed in <xref target="Extensions" format="default"/>.
a security </dd>
target in a bundle. Were some Other Security Block (OSB) to be de </dl>
fined <t>
providing an integrity service, then the operations OP(bib-integr
ity, target)
and OP(osb-integrity, target) MAY both be present in the same bun
dle if so allowed
by the definition of the OSB, as discussed in <xref target="Exten
sions"/>.
</t>
</list>
</t>
<t>
NOTES: NOTES:
<list style="bullets"> </t>
<t> <ul spacing="normal">
A security block may be removed from a bundle as part of security <li>
processing A security block may be removed from a bundle as part
at a waypoint node with a new security block being added to the b of security processing at a waypoint node with a new
undle by that security block being added to the bundle by that
node. In this case, conflicting security blocks never co-exist in node. In this case, conflicting security blocks never
the bundle at the same coexist in the bundle at the same time and the
time and the uniqueness requirement is not violated. uniqueness requirement is not violated.
</t> </li>
<li>
<t> A ciphertext integrity-protection mechanism (such as associated
A cipher text integrity mechanism (such as associated authenticat authenticated data) calculated by a cipher suite and
ed data) calculated transported in a BCB is considered part of the
by a cipher suite and transported in a BCB is considered part of confidentiality service; therefore, it is unique from the
the confidentiality plaintext integrity service provided by a BIB.
service and, therefore, unique from the plain text integrity serv </li>
ice provided by a BIB. <li>
</t> The security blocks defined in this specification (BIB
and BCB) are designed with the intention that the BPA
<t> adding these blocks is the authoritative source of the
The security blocks defined in this specification (BIB and BCB) a security service. If a BPA adds a BIB on a security
re designed with target, then the BIB is expected to be the
the intention that the BPA adding these blocks is the authoritati authoritative source of integrity for that security
ve source of the target. If a BPA adds a BCB to a security target, then
security service. If a BPA adds a BIB on a security target, then the BCB is expected to be the authoritative source of
the BIB is expected confidentiality for that security target. More complex
to be the authoritative source of integrity for that security tar scenarios, such as having multiple nodes in a network
get. If a BPA adds sign the same security target, can be accommodated
a BCB to a security target, then the BCB is expected to be the au using the definition of custom security contexts (see <xref
thoritative source target="sec_ctx" format="default"/>) and/or the
of confidentiality for that security target. More complex scenari definition of OSBs (see <xref
os, such as target="Extensions" format="default"/>).
having multiple nodes in a network sign the same security target, </li>
can be </ul>
accommodated using the definition of custom security contexts </section>
(<xref target="sec_ctx"/>) and/or the definition of other securit <section anchor="sec_blocks_mult" toc="default" numbered="true">
y blocks (<xref target="Extensions"/>). <name>Target Multiplicity</name>
</t> <t>
A single security block <bcp14>MAY</bcp14> represent
</list>
</t>
</section>
<section anchor="sec_blocks_mult" title="Target Multiplicity" toc="default">
<t>
A single security block MAY represent
multiple security operations as a way of reducing the overall number multiple security operations as a way of reducing the overall number
of security blocks present in a bundle. In these circumstances, of security blocks present in a bundle. In these circumstances,
reducing the number of security blocks in the bundle reduces the reducing the number of security blocks in the bundle reduces the
amount of redundant information in the bundle. amount of redundant information in the bundle.
</t> </t>
<t>
<t>
A set of security operations can be represented by a single security A set of security operations can be represented by a single security
block when all of the following conditions are true. block when all of the following conditions are true.
<list style="symbols"> </t>
<t> <ul spacing="normal">
<li>
The security operations apply the same security service. For The security operations apply the same security service. For
example, they are all integrity operations or all example, they are all integrity operations or all
confidentiality operations. confidentiality operations.
</t> </li>
<t> <li>
The security context parameters for the The security context parameters for the
security operations are identical. security operations are identical.
</t> </li>
<t> <li>
The security source for the security operations is the same, The security source for the security operations is the same,
meaning the set of operations are being added by the meaning the set of operations are being added by the
same node. same node.
</t> </li>
<t> <li>
No security operations have the same security target, as that No security operations have the same security target, as that
would violate the need for security operations to be unique. would violate the need for security operations to be unique.
</t> </li>
<t> <li>
None of the security operations conflict with security None of the security operations conflict with security
operations already present in the bundle. operations already present in the bundle.
</t> </li>
</list> </ul>
</t> <t>
<t>
When representing multiple security operations in a single security When representing multiple security operations in a single security
block, the information that is common across all operations is block, the information that is common across all operations is
represented once in the security block, and the information which is represented once in the security block; the information that is
different (e.g., the security targets) are represented individually. different (e.g., the security targets) is represented individually.
</t> </t>
<t> <t>
It is RECOMMENDED that if a node processes any security operation in If a node processes any security operation in a security block, it is <
a security block that it process all security operations in the bcp14>RECOMMENDED</bcp14> that it process all
security block. This allows security sources to assert that the set of security operations in the security block. This allows
security operations in a security block are expected to be processed security sources to assert that the set of security
by the same security acceptor. However, the determination operations in a security block are expected to be processed
of whether a node actually is a security acceptor or not is a matter by the same security acceptor. However, the determination of
of the policy of the node itself. In cases where a receiving node whether a node actually is a security acceptor or not is a
determines that it is the security acceptor of only a subset of the matter of the policy of the node itself. In cases where a
security operations in a security block, the node may choose to only receiving node determines that it is the security acceptor of
process that subset of security operations. only a subset of the security operations in a security block,
</t> the node may choose to only process that subset of security
</section> operations.
</t>
<section anchor="sec_blocks_tgtid" title="Target Identification"> </section>
<t> <section anchor="sec_blocks_tgtid" numbered="true" toc="default">
<name>Target Identification</name>
<t>
A security target is a block in the bundle to which a security A security target is a block in the bundle to which a security
service applies. This target must be uniquely and unambiguously service applies. This target must be uniquely and unambiguously
identifiable when processing a security block. The definition of the identifiable when processing a security block. The definition of the
extension block header from <xref target="I-D.ietf-dtn-bpbis"/> extension block header from <xref target="RFC9171" format="default"/>
provides a "Block Number" field suitable for this purpose. Therefore, provides a "block number" field suitable for this purpose. Therefore,
a security target in a security block MUST be represented as the a security target in a security block <bcp14>MUST</bcp14> be represente
Block Number of the target block. d as the
</t> block number of the target block.
</section> </t>
</section>
<section anchor="sec_blocks_rep" title="Block Representation" toc="default"> <section anchor="sec_blocks_rep" toc="default" numbered="true">
<t> <name>Block Representation</name>
<t>
Each security block uses the Canonical Bundle Block Format as Each security block uses the Canonical Bundle Block Format as
defined in <xref target="I-D.ietf-dtn-bpbis"/>. That is, each defined in <xref target="RFC9171" format="default"/>. That is, each
security block is comprised of the following elements: security block is comprised of the following elements:
<list style="symbols"> </t>
<t>block type code</t> <ul spacing="compact">
<t>block number </t> <li>block type code</li>
<t>block processing control flags</t> <li>block number </li>
<t>CRC type</t> <li>block processing control flags</li>
<t>block-type-specific-data</t> <li>cyclic redundancy check (CRC) type</li>
<t>CRC field (if present)</t> <li>block-type-specific data</li>
</list> <li>CRC field (if present)</li>
</t> </ul>
<t>
<t>
Security-specific information for a security block is captured in the Security-specific information for a security block is captured in the
block-type-specific-data field. block-type-specific data field.
</t> </t>
</section> </section>
<section anchor="sec_blocks_asb" numbered="true" toc="default">
<section anchor="sec_blocks_asb" title="Abstract Security Block"> <name>Abstract Security Block</name>
<t> <t>
The structure of the security-specific portions of a security block The structure of the security-specific portions of a security block
is identical for both the BIB and BCB Block Types. Therefore, this is identical for both the BIB and BCB block types. Therefore, this
section defines an Abstract Security Block (ASB) data structure and section defines an Abstract Security Block (ASB) data structure and
discusses the definition, processing, and other constraints for using discusses its definition, its processing, and other constraints for usi ng
this structure. An ASB is never directly instantiated within a this structure. An ASB is never directly instantiated within a
bundle, it is only a mechanism for discussing the common aspects of bundle, it is only a mechanism for discussing the common aspects of
BIB and BCB security blocks. BIB and BCB security blocks.
</t> </t>
<t>
<t> The fields of the ASB <bcp14>SHALL</bcp14> be as follows,
The fields of the ASB SHALL be as follows, listed in the order in listed in the order in which they must appear. The encoding
which they must appear. The encoding of these fields MUST be in of these fields <bcp14>MUST</bcp14> be in accordance with the
accordance with the canonical forms provided in <xref target="CanonBund canonical forms provided in <xref target="CanonBundle"
le"/>. format="default"/>.
<list style="hanging" hangIndent="6">
<t hangText="Security Targets:"> <vspace/>
This field identifies the block(s) targeted by the security
operation(s) represented by this security block. Each target
block is represented by its unique Block Number. This field
SHALL be represented by a CBOR array of data items. Each target
within this CBOR array SHALL be represented by a CBOR unsigned
integer. This array MUST have at least 1 entry and each entry
MUST represent the Block Number of a block that exists in the
bundle. There MUST NOT be duplicate entries in this array. The
order of elements in this list has no semantic meaning outside of
the context of this block. Within the block, the ordering of
targets must match the ordering of results associated with
these targets.
</t>
<t hangText="Security Context Id:"> <vspace/>
This field identifies the security context used to implement
the security service represented by this block and applied to
each security target. This field SHALL be represented by a CBOR
unsigned integer. The values for this Id should come from the
registry defined in <xref target="SecCtx"/>
</t>
<t hangText="Security Context Flags:"> <vspace/>
This field identifies which optional fields are present in the
security block. This field SHALL be represented as a CBOR
unsigned integer whose contents shall be
interpreted as a bit field. Each bit in this bit field indicates
the presence (bit set to 1) or absence (bit set to 0) of
optional data in the security block. The association of bits to
security block data is defined as follows.
<list style="hanging" hangIndent="7"> </t>
<t hangText="Bit 0"> (the least-significant bit, 0x01): Securi <dl newline="true" spacing="normal" indent="6">
ty Context <dt>Security Targets:</dt>
Parameters Present Flag. </t> <dd>
<t hangText="Bit >0">Reserved </t> This field identifies the block(s) targeted by the
</list> security operation(s) represented by this security
block. Each target block is represented by its unique
block number. This field <bcp14>SHALL</bcp14> be
represented by a Concise Binary Object Representation
(CBOR) array of data items. Each target within this
CBOR array <bcp14>SHALL</bcp14> be represented by a
CBOR unsigned integer. This array <bcp14>MUST</bcp14>
have at least one entry and each entry
<bcp14>MUST</bcp14> represent the block number of a
block that exists in the bundle. There <bcp14>MUST
NOT</bcp14> be duplicate entries in this array. The
order of elements in this list has no semantic meaning
outside of the context of this block. Within the block,
the ordering of targets must match the ordering of
results associated with these targets.
</dd>
<dt>Security Context Id:</dt>
<dd>
This field identifies the security context used to
implement the security service represented by this
block and applied to each security target. This field
<bcp14>SHALL</bcp14> be represented by a CBOR unsigned
integer. The values for this Id should come from the
registry defined in <xref target="SecCtx"
format="default"/>.
</dd>
<dt>Security Context Flags:</dt>
<dd>
<t>
This field identifies which optional fields are present
in the security block. This field <bcp14>SHALL</bcp14>
be represented as a CBOR unsigned integer whose
contents shall be interpreted as a bit field. Each bit
in this bit field indicates the presence (bit set to 1)
or absence (bit set to 0) of optional data in the
security block. The association of bits to security
block data is defined as follows.
Implementations MUST set reserved bits to 0 when writing this
field and MUST ignore the values of reserved bits when reading th
is
field. For unreserved bits, a value of 1 indicates that the asso
ciated
security block field MUST be included in the security block. A
value of 0 indicates that the associated security block field
MUST NOT be in the security block.
</t> </t>
<dl newline="false" spacing="normal" indent="10">
<dt>Bit 0</dt>
<dd> (the least-significant bit, 0x01): "Security context
parameters present" flag. </dd>
<dt>Bit &gt;0</dt>
<dd>Reserved </dd>
</dl>
<t>
<t hangText="Security Source:"> <vspace/> Implementations <bcp14>MUST</bcp14> set reserved bits
This field identifies the Endpoint that inserted the security to 0 when writing this field and <bcp14>MUST</bcp14>
block in the bundle. This field SHALL be ignore the values of reserved bits when reading this
represented by a CBOR array in accordance with field. For unreserved bits, a value of 1 indicates
<xref target="I-D.ietf-dtn-bpbis"/> rules for that the associated security block field
representing Endpoint Identifiers (EIDs). <bcp14>MUST</bcp14> be included in the security
block. A value of 0 indicates that the associated
security block field <bcp14>MUST NOT</bcp14> be in the
security block.
</t> </t>
</dd>
<t hangText="Security Context Parameters (Optional):"> <vspace/> <dt>Security Source:</dt>
<dd>
This field identifies the BPA that inserted the security block
in the bundle. Also, any node ID of the node of which the BPA
is a component. This field <bcp14>SHALL</bcp14> be
represented by a CBOR array in accordance with the rules in
<xref target="RFC9171" format="default"/> for
representing endpoint IDs (EIDs).
</dd>
<dt>Security Context Parameters (Optional):</dt>
<dd>
<t>
This field captures one or more security context parameters This field captures one or more security context parameters
that should be used when processing that should be used when processing
the security service described by this security block. This the security service described by this security block. This
field SHALL be represented by a CBOR array. Each entry in this field <bcp14>SHALL</bcp14> be represented by a CBOR array. Each entry in this
array is a single security context parameter. A single array is a single security context parameter. A single
parameter SHALL also be represented as a CBOR array comprising parameter <bcp14>SHALL</bcp14> also be represented as a CBOR arra
a 2-tuple of the id and value of the parameter, as follows. y comprising
a 2-tuple of the Id and value of the parameter, as follows.
<list style="symbols"> </t>
<t> <dl spacing="normal">
Parameter Id. This field identifies which <dt>Parameter Id:</dt><dd>This field identifies which
parameter is being specified. This field SHALL be parameter is being specified. This field <bcp14>SHALL</bcp1
4> be
represented as a CBOR unsigned integer. Parameter Ids represented as a CBOR unsigned integer. Parameter Ids
are selected as described in <xref target="parmresult"/>. are selected as described in <xref target="parmresult" form
</t> at="default"/>.
<t> </dd>
Parameter Value. This field captures the value <dt>Parameter Value:</dt><dd>This field captures the value
associated with this parameter. This field SHALL be associated with this parameter. This field <bcp14>SHALL</bc
p14> be
represented by the applicable CBOR representation of the represented by the applicable CBOR representation of the
parameter, in accordance with <xref target="parmresult"/>. parameter, in accordance with <xref target="parmresult" for
</t> mat="default"/>.
</list> </dd>
<vspace/><vspace/> </dl>
<t>
The logical layout of the parameters array is The logical layout of the parameters array is
illustrated in <xref target="parms_tbl"/>. illustrated in <xref target="parms_tbl" format="default"/>.
<figure anchor="parms_tbl" title="Security Context Parameters">
<artwork align="center">&#xA;<!--
-->+----------------+----------------+ +---------------
-+&#xA;<!--
-->| Parameter 1 | Parameter 2 | ... | Parameter N
|&#xA;<!--
-->+------+---------+------+---------+ +------+--------
-+&#xA;<!--
-->| Id | Value | Id | Value | | Id | Value
|&#xA;<!--
-->+------+---------+------+---------+ +------+--------
-+
</artwork>
</figure>
</t> </t>
<figure anchor="parms_tbl">
<name>Security Context Parameters</name>
<artwork align="center" name="" type="" alt="">
+----------------+----------------+ +----------------+
| Parameter 1 | Parameter 2 | ... | Parameter N |
+------+---------+------+---------+ +------+---------+
| Id | Value | Id | Value | | Id | Value |
+------+---------+------+---------+ +------+---------+</artwork>
</figure>
</dd>
<t hangText="Security Results:"> <vspace/> <dt>Security Results:</dt>
<dd>
<t>
This field captures the results of applying a security service This field captures the results of applying a security service
to the security targets of the security block. This field SHALL to the security targets of the security block. This field <bcp14> SHALL</bcp14>
be represented as a CBOR array of target results. Each entry in be represented as a CBOR array of target results. Each entry in
this array represents the set of security results for a this array represents the set of security results for a
specific security target. The target results MUST be ordered specific security target. The target results <bcp14>MUST</bcp14> be ordered
identically to the Security Targets field of the security block. identically to the Security Targets field of the security block.
This means that the first set of target results in this array This means that the first set of target results in this array
corresponds to the first entry in the Security Targets field of corresponds to the first entry in the Security Targets field of
the security block, and so on. There MUST be one entry in this the security block, and so on. There <bcp14>MUST</bcp14> be one e ntry in this
array for each entry in the Security Targets field of the array for each entry in the Security Targets field of the
security block. security block.
<vspace/> <vspace/> </t>
<t>
The set of security results for a target is also represented as The set of security results for a target is also represented as
a CBOR array of individual results. An individual result is a CBOR array of individual results. An individual result is
represented as a 2-tuple of a result id and a result value, represented as a CBOR array comprising a 2-tuple of a result Id a nd a result value,
defined as follows. defined as follows.
<list style="symbols"> </t>
<t> <dl spacing="normal">
Result Id. This field identifies which security result is <dt>Result Id:</dt><dd>This field identifies which security result
is
being specified. Some security results capture the being specified. Some security results capture the
primary output of a cipher suite. Other security results primary output of a cipher suite. Other security results
contain additional annotative information from cipher contain additional annotative information from cipher
suite processing. This field SHALL be represented as a suite processing. This field <bcp14>SHALL</bcp14> be repres ented as a
CBOR unsigned integer. Security result Ids will be as CBOR unsigned integer. Security result Ids will be as
specified in <xref target="parmresult"/>. specified in <xref target="parmresult" format="default"/>.
</t> </dd>
<t> <dt>Result Value:</dt><dd>This field captures the value associated
Result Value. This field captures the value associated with the result. This field <bcp14>SHALL</bcp14> be represe
with the result. This field SHALL be represented by the nted by the
applicable CBOR representation of the result value, in applicable CBOR representation of the result value, in
accordance with <xref target="parmresult"/>. accordance with <xref target="parmresult" format="default"/
</t> >.
</list> </dd>
</dl>
<t>
The logical layout of the security results array is illustrated The logical layout of the security results array is illustrated
in <xref target="res_tbl"/>. In this figure there are N in <xref target="res_tbl" format="default"/>. In this figure, the re are N
security targets for this security block. The first security security targets for this security block. The first security
target contains M results and the Nth security target contains target contains M results and the Nth security target contains
K results. K results.
<figure anchor="res_tbl" title="Security Results">
<artwork align="center">&#xA;<!--
-->+------------------------------+ +------------------
------------+&#xA;<!--
-->| Target 1 | | Target
N |&#xA;<!--
-->+------------+----+------------+ +------------------
------------+&#xA;<!--
-->| Result 1 | | Result M | ... | Result 1 | |
Result K |&#xA;<!--
-->+----+-------+ .. +----+-------+ +----+-------+ .. +
----+-------+&#xA;<!--
-->| Id | Value | | Id | Value | | Id | Value | |
Id | Value |&#xA;<!--
-->+----+-------+ +----+-------+ +----+-------+ +
----+-------+
</artwork>
</figure>
</t>
</list>
</t>
</section>
<section anchor="BIB" title="Block Integrity Block" toc="default">
<t>
A BIB is a bundle extension block with the following characteristics.
<list>
<t>
The Block Type Code value is as specified in
<xref target="BlockType"/>.
</t> </t>
<figure anchor="res_tbl">
<name>Security Results</name>
<artwork align="center" name="" type="" alt="">
+--------------------------+ +---------------------------+
| Target 1 | | Target N |
+----------+----+----------+ +---------------------------+
| Result 1 | | Result M | ... | Result 1 | | Result K |
+----+-----+ .. +----+-----+ +---+------+ .. +----+------+
| Id |Value| | Id |Value| | Id |Value| | Id | Value|
+----+-----+ +----+-----+ +----+-----+ +----+------+</artwork>
</figure>
</dd>
</dl>
</section>
<section anchor="BIB" toc="default" numbered="true">
<name>Block Integrity Block</name>
<t>
A BIB is a BP extension block with the following characteristics.
<t> </t>
The block-type-specific-data field follows the structure of the <ul spacing="normal">
<li>
The block type code value is as specified in
<xref target="BlockType" format="default"/>.
</li>
<li>
The block-type-specific data field follows the structure of the
ASB. ASB.
</t> </li>
<li>
<t> A security target listed in the Security Targets field <bcp14>MUS
A security target listed in the Security Targets field MUST NOT T NOT</bcp14>
reference a security block defined in this specification (e.g., reference a security block defined in this specification (e.g.,
a BIB or a BCB). a BIB or a BCB).
</t> </li>
<li>
<t> The security context <bcp14>MUST</bcp14> utilize an authenticatio
The Security Context MUST utilize an authentication mechanism or n mechanism or
an error detection mechanism. an error detection mechanism.
</t> </li>
</list> </ul>
</t> <t>
<t>
Notes: Notes:
<list style="symbols"> </t>
<t> <ul spacing="normal">
Designers SHOULD carefully consider the effect of setting flags t <li>
hat either discard the Designers <bcp14>SHOULD</bcp14> carefully consider the effect of
setting flags that either discard the
block or delete the bundle in the event that this block cannot block or delete the bundle in the event that this block cannot
be processed. be processed.
</t> </li>
<li>
<t>
Since OP(bib-integrity, target) is allowed only once in a bundle Since OP(bib-integrity, target) is allowed only once in a bundle
per target, it is RECOMMENDED that users wishing to support per target, it is <bcp14>RECOMMENDED</bcp14> that users wishing t
multiple integrity mechanisms for the same target define a o support
multiple integrity-protection mechanisms for the same target defi
ne a
multi-result security context. Such a context could generate multi-result security context. Such a context could generate
multiple security results for the same security target using diff erent multiple security results for the same security target using diff erent
integrity-protection mechanisms or different configurations for t he integrity-protection mechanisms or different configurations for t he
same integrity-protection mechanism. same integrity-protection mechanism.
</t> </li>
<li>
<t> A BIB is used to verify the plaintext integrity of its security
A BIB is used to verify the plain text integrity of its security target. However, a single BIB <bcp14>MAY</bcp14> include security
target. However, a single BIB MAY include security results for results for
blocks other than its security target when doing so establishes a blocks other than its security target when doing so establishes a
needed relationship between the BIB security target and other blo cks needed relationship between the BIB security target and other blo cks
in the bundle (such as the primary block). in the bundle (such as the primary block).
</t> </li>
<li>
<t> Security information <bcp14>MAY</bcp14> be checked at any hop on
Security information MAY be checked at any hop on the the
way to the bundle destination that has access to the required key ing way to the bundle destination that has access to the required key ing
information, in accordance with <xref target="interact"/>. information, in accordance with <xref target="interact" format="d
</t> efault"/>.
</li>
</list> </ul>
</t> </section>
</section> <section anchor="BCB" toc="default" numbered="true">
<name>Block Confidentiality Block</name>
<section anchor="BCB" title="Block Confidentiality Block" toc="default"> <t>
<t> A BCB is a BP extension block with the following characteristics.
A BCB is a bundle extension block with the following characteristics.
<list>
<t>
The Block Type Code value is as specified in
<xref target="BlockType"/>.
</t>
<t>
The Block Processing Control flags value can be set to whatever
values are required by local policy with the following exceptions
.
BCB blocks MUST have the "block must be replicated in every fragm
ent" flag set if
one of the targets is the payload block. Having that BCB in each
fragment
indicates to a receiving node that the payload portion of each
fragment represents cipher text. BCB blocks MUST NOT have the "bl
ock must
be removed from bundle if it can't be processed" flag set. Removi
ng a BCB from
a bundle without decrypting its security targets removes informat
ion from
the bundle necessary for their later decryption.
</t>
<t> </t>
The block-type-specific-data fields follow the structure of the <ul spacing="normal">
<li>
The block type code value is as specified in
<xref target="BlockType" format="default"/>.
</li>
<li><t>
The block processing control flags value can be set to
whatever values are required by local policy with the
following exceptions: </t>
<ul>
<li>
BCBs <bcp14>MUST</bcp14>
have the "Block must be replicated in every fragment"
flag set if one of the targets is the payload
block. Having that BCB in each fragment indicates to a
receiving node that the payload portion of each
fragment represents ciphertext. </li>
<li>
BCBs <bcp14>MUST
NOT</bcp14> have the "Block must be removed from bundle
if it can't be processed" flag set. Removing a BCB from
a bundle without decrypting its security targets
removes information from the bundle necessary for their
later decryption.
</li>
</ul>
</li>
<li>
The block-type-specific data fields follow the structure of the
ASB. ASB.
</t> </li>
<li>
<t> A security target listed in the Security Targets field
A security target listed in the Security Targets field can can reference the payload block, a non-security
reference the payload block, a non-security extension block, extension block, or a BIB. A BCB <bcp14>MUST
or a BIB. A BCB MUST NOT include another BCB as a security NOT</bcp14> include another BCB as a security target. A
target. A BCB MUST NOT target the primary block. A BCB MUST BCB <bcp14>MUST NOT</bcp14> target the primary block. A
NOT target a BIB block unless it shares a security target BCB <bcp14>MUST NOT</bcp14> target a BIB unless
with that BIB block. it shares a security target with that BIB.
</t> </li>
<li>
<t> Any security context used by a BCB <bcp14>MUST</bcp14> utilize a
Any Security Context used by a BCB MUST utilize a confidentiality confidentiality
cipher that provides authenticated encryption with cipher that provides authenticated encryption with
associated data (AEAD). associated data (AEAD).
</t> </li>
<li>
<t>
Additional information created by a cipher suite (such as Additional information created by a cipher suite (such as
an authentication tag) can be placed either in a an authentication tag) can be placed either in a
security result field or in the generated cipher text. The security result field or in the generated ciphertext. The
determination of where to place this information is a function of the determination of where to place this information is a function of the
cipher suite and security context used. cipher suite and security context used.
</t> </li>
</list> </ul>
</t> <t>
<t>
The BCB modifies the contents of its security target(s). When a BCB The BCB modifies the contents of its security target(s). When a BCB
is applied, the security target body data are encrypted "in-place". is applied, the security target body data are encrypted "in-place".
Following encryption, the security target block-type-specific-data Following encryption, the security target block-type-specific data
field contains cipher text, not plain text. field contains ciphertext, not plaintext.
</t> </t>
<t>Notes:
<t>Notes: </t>
<list style="symbols"> <ul spacing="normal">
<t> <li>
It is RECOMMENDED that designers carefully It is <bcp14>RECOMMENDED</bcp14> that designers carefully
consider the effect of setting flags that delete the bundle in consider the effect of setting flags that delete the bundle in
the event that this block cannot be processed. the event that this block cannot be processed.
</t> </li>
<t> <li>
The BCB block processing control flags can be set independently The BCB block processing control flags can be set independently
from the processing control flags of the security target(s). The from the processing control flags of the security target(s). The
setting of such flags should be an implementation/policy setting of such flags should be an implementation/policy
decision for the encrypting node. decision for the encrypting node.
</t> </li>
</list> </ul>
</t> </section>
</section> <section anchor="interact" toc="default" numbered="true">
<name>Block Interactions</name>
<section anchor="interact" title="Block Interactions" toc="default"> <t>
<t>
The security block types defined in this specification are The security block types defined in this specification are
designed to be as independent as possible. However, there are some designed to be as independent as possible.
cases where security blocks may share a security target creating However, there are some cases where security blocks may share a
processing dependencies. security target; this sharing creates processing dependencies.
</t> </t>
<t>
<t> If a BCB and a BIB share a security target, an undesirable
If a security target of a BCB is also a security target of a BIB, condition occurs: a waypoint would be unable to validate the BIB
an undesirable condition occurs where a waypoint would because the shared security target has been encrypted by the BCB.
be unable to validate the BIB because one of its security target's To address this situation, the
contents have been encrypted by a BCB. To address this situation the following processing rules <bcp14>MUST</bcp14> be followed:
following processing rules MUST be followed. </t>
</t> <ul spacing="normal">
<li>
<t> When adding a BCB to a bundle, if some (or all) of the
<list style="symbols"> security targets of the BCB match all of the
<t> security targets of an existing BIB, then the existing
When adding a BCB to a bundle, if some (or all) of the security BIB <bcp14>MUST</bcp14> also be encrypted. This can be
targets of the BCB also match all of the security targets of accomplished either by adding a new BCB that targets
an existing BIB, then the existing BIB MUST also be encrypted. the existing BIB or by adding the BIB to the list of
This can be accomplished by either adding a new BCB that security targets for the BCB. Deciding which way to
targets the existing BIB, or by adding the BIB to represent this situation is a matter of security
the list of security targets for the BCB. Deciding which way policy.
to represent this situation is a matter of security policy. </li>
</t> <li>
<t> When adding a BCB to a bundle, if some (or all) of the
When adding a BCB to a bundle, if some (or all) of the security security targets of the BCB match some (but not all) of
targets of the BCB match some (but not all) of the security the security targets of a BIB, then that BIB
targets of a BIB then that BIB MUST be altered in the following <bcp14>MUST</bcp14> be altered in the following
way. Any security results in the BIB associated with the BCB way. Any security results in the BIB associated with
security targets MUST be removed from the BIB and placed in the BCB security targets <bcp14>MUST</bcp14> be removed
a new BIB. This newly created BIB MUST then be encrypted. from the BIB and placed in a new BIB. This newly
The encryption of the new BIB can be accomplished by created BIB <bcp14>MUST</bcp14> then be encrypted. The
either adding a new BCB that targets the new BIB, or by encryption of the new BIB can be accomplished either by
adding the new BIB to the list of security targets for the BCB. adding a new BCB that targets the new BIB or by adding
Deciding which way to represent this situation is a matter of the new BIB to the list of security targets for the
security policy. BCB. Deciding which way to represent this situation is
</t> a matter of security policy.
</li>
<t> <li>
A BIB MUST NOT be added for a security target that is already A BIB <bcp14>MUST NOT</bcp14> be added for a security
the security target of a BCB as this would cause target that is already the security target of a BCB as
ambiguity in block processing order. this would cause ambiguity in block processing order.
</t> </li>
<li>
<t> A BIB integrity value <bcp14>MUST NOT</bcp14> be
A BIB integrity value MUST NOT be checked if the BIB is the checked if the BIB is the security target of an
security target of an existing BCB. In this case, the BIB existing BCB. In this case, the BIB data is encrypted.
data is encrypted. </li>
</t> <li>
<t> A BIB integrity value <bcp14>MUST NOT</bcp14> be
A BIB integrity value MUST NOT be checked if the security checked if the security target associated with that
target associated with that value is also the security target of value is also the security target of a BCB. In such a
a BCB. In such case, the security target data contains ciphertext as
a case, the security target data contains cipher text as it has it has been encrypted.
been encrypted. </li>
</t> <li>
<t> As mentioned in <xref target="BIB" format="default"/>,
As mentioned in <xref target="BIB"/>, a BIB MUST NOT have a a BIB <bcp14>MUST NOT</bcp14> have a BCB as its
BCB as its security target. security target.
</t> </li>
</list> </ul>
</t> <t>
These restrictions on block interactions impose a necessary
<t> ordering when applying security operations within a
These restrictions on block interactions impose a necessary ordering bundle. Specifically, for a given security target, BIBs
when applying security operations within a bundle. Specifically, for <bcp14>MUST</bcp14> be added before BCBs. This ordering
a given security target, BIBs MUST be added before BCBs. This <bcp14>MUST</bcp14> be preserved in cases where the current
ordering MUST be preserved in cases where the current BPA is adding BPA is adding all of the security blocks for the bundle or
all of the security blocks for the bundle or whether the BPA is a where the BPA is a waypoint adding new security blocks to a
waypoint adding new security blocks to a bundle that already contains bundle that already contains security blocks.
security blocks. </t>
</t> <t>
<t> In cases where a security source wishes to calculate both a
In cases where a security source wishes to plaintext integrity-protection mechanism and encrypt a security target,
calculate both a plain text integrity mechanism and encrypt a a BCB with a security context that generates an
security target, a BCB with a security context that generates an integr integrity-protection mechanism as one or more additional
ity-protection mechanism security results <bcp14>MUST</bcp14> be used instead of
as one or more additional security results MUST be used instead of adding both a BIB and then a BCB for the security target at
adding both a BIB and then a BCB for the security target at the the security source.
security source. </t>
</t> </section>
</section> <section anchor="parmresult" numbered="true" toc="default">
<name>Parameter and Result Identification</name>
<section anchor="parmresult" title="Parameter and Result Identification"> <t>
<t> Each security context <bcp14>MUST</bcp14> define its own
Each security context MUST define its own context parameters and result context parameters and results. Each defined parameter and
s. result is represented as the tuple of an identifier and a
Each defined parameter and result is represented as the tuple of an value. Identifiers are always represented as a CBOR unsigned
identifier and a value. Identifiers are always represented as a CBOR integer. The CBOR encoding of values is as defined by the
unsigned integer. The CBOR encoding of values is as defined by the
security context specification. security context specification.
</t> </t>
<t> <t>
Identifiers MUST be unique for a given security context but do not need Identifiers <bcp14>MUST</bcp14> be unique for a given
to be unique amongst all security contexts. security context but do not need to be unique amongst all
</t> security contexts.
<t> </t>
An example of a security context can be found at <xref target="I-D.ietf <t>
-dtn-bpsec-default-sc"/>. An example of a security context can be found in <xref
</t> target="RFC9173" format="default"/>.
</section> </t>
</section>
<section anchor="bsp_example" title="BSP Block Examples" toc="default"> <section anchor="bsp_example" toc="default" numbered="true">
<t> <name>BPSec Block Examples</name>
<t>
This section provides two examples of BPSec blocks applied to This section provides two examples of BPSec blocks applied to
a bundle. In the first example, a single node adds several bundles. In the first example, a single node adds several
security operations to a bundle. In the second example, a waypoint security operations to a bundle. In the second example, a
node received the bundle created in the first example and adds waypoint node received the bundle created in the first
additional security operations. In both examples, the first column example and adds additional security operations. In both
represents blocks within a bundle and the second column represents examples, the first column represents blocks within a bundle
the Block Number for the block, using the terminology B1...Bn for the and the second column represents the block number for the
purpose of illustration. block, using the terminology B1...Bn for the purpose of
</t> illustration.
</t>
<section title="Example 1: Constructing a Bundle with Security"> <section numbered="true" toc="default">
<t> <name>Example 1: Constructing a Bundle with Security</name>
In this example a bundle has four non-security-related blocks: the <t>
primary block (B1), two extension blocks (B4,B5), and a payload In this example, a bundle has four non-security-related
block (B6). The bundle source wishes to provide an integrity blocks: the primary block (B1), two extension blocks
signature of the plain text associated with the primary block, the (B4, B5), and a payload block (B6). The bundle source
second extension block, and the payload. The bundle source also wishes to provide an integrity signature of the plaintext
wishes to provide confidentiality for the first extension block. associated with the primary block, the second extension
The resultant bundle is illustrated in <xref target="bsp_ex1"/> and block, and the payload. The bundle source also wishes to
the security actions are described below. provide confidentiality for the first extension block.
The resultant bundle is illustrated in <xref
<figure anchor="bsp_ex1" title="Security at Bundle Creation"> target="bsp_ex1" format="default"/> and the security
<artwork align="center">&#xA;<!-- actions are described below.
--> Block in Bundle ID&#xA;<!-- </t>
-->+==========================================+====+&#xA;<!-- <figure anchor="bsp_ex1">
-->| Primary Block | B1 |&#xA;<!-- <name>Security at Bundle Creation</name>
-->+------------------------------------------+----+&#xA;<!-- <artwork align="center" name="" type="" alt="">
-->| BIB | B2 |&#xA;<!-- Block in Bundle ID
-->| OP(bib-integrity, targets=B1, B5, B6) | |&#xA;<!-- +==========================================+====+
-->+------------------------------------------+----+&#xA;<!-- | Primary Block | B1 |
-->| BCB | B3 |&#xA;<!-- +------------------------------------------+----+
-->| OP(bcb-confidentiality, target=B4) | |&#xA;<!-- | BIB | B2 |
-->+------------------------------------------+----+&#xA;<!-- | OP(bib-integrity, targets = B1, B5, B6)| |
-->| Extension Block (encrypted) | B4 |&#xA;<!-- +------------------------------------------+----+
-->+------------------------------------------+----+&#xA;<!-- | BCB | B3 |
-->| Extension Block | B5 |&#xA;<!-- | OP(bcb-confidentiality, target = B4) | |
-->+------------------------------------------+----+&#xA;<!-- +------------------------------------------+----+
-->| Payload Block | B6 |&#xA;<!-- | Extension Block (encrypted) | B4 |
-->+------------------------------------------+----+ +------------------------------------------+----+
</artwork> | Extension Block | B5 |
</figure> +------------------------------------------+----+
</t> | Payload Block | B6 |
<t> +------------------------------------------+----+</artwork>
</figure>
<t>
The following security actions were applied to this bundle at its The following security actions were applied to this bundle at its
time of creation. time of creation.
<list style="symbols"> </t>
<ul spacing="normal">
<t> <li>
An integrity signature applied to the canonical form of the An integrity signature applied to the canonical form of the
primary block (B1), the canonical form of the block-type-speci primary block (B1), the canonical form of the block-type-speci
fic-data field fic data field
of the second extension block (B5) and the canonical form of t of the second extension block (B5), and the canonical form of
he the
payload block (B6). This is accomplished by a single BIB (B2) payload block (B6). This is accomplished by a single BIB (B2)
with multiple targets. A single BIB is used in this case with multiple targets. A single BIB is used in this case
because all three targets share a security source, security because all three targets share a security source, security
context, and security context parameters. Had this not been context, and security context parameters. Had this not been
the case, multiple BIBs could have been added instead. the case, multiple BIBs could have been added instead.
</t> </li>
<li>
<t>
Confidentiality for the first extension block (B4). This is Confidentiality for the first extension block (B4). This is
accomplished by a BCB (B3). Once applied, the block-type-speci accomplished by a BCB (B3). Once applied, the block-type-speci
fic-data fic data
field of extension block B4 is encrypted. The BCB MUST field of extension block B4 is encrypted. The BCB <bcp14>MUST<
hold an authentication tag for the cipher text either /bcp14>
in the cipher text that now populates the first extension hold an authentication tag for the ciphertext either
in the ciphertext that now populates the first extension
block or as a security result in the BCB itself, depending block or as a security result in the BCB itself, depending
on which security context is used to form the BCB. A plain tex t on which security context is used to form the BCB. A plaintext
integrity signature may also exist as a security result in integrity signature may also exist as a security result in
the BCB if one is provided by the selected confidentiality the BCB if one is provided by the selected confidentiality
security context. security context.
</t> </li>
</list> </ul>
</t> </section>
</section> <section numbered="true" toc="default">
<name>Example 2: Adding More Security at a New Node</name>
<section title="Example 2: Adding More Security At A New Node"> <t>
<t> Consider that the bundle as it is illustrated in <xref
Consider that the bundle as it is illustrated in target="bsp_ex1" format="default"/> is now received by a
<xref target="bsp_ex1"/> is now received by a waypoint node that waypoint node that wishes to encrypt the second extension
wishes to encrypt the second extension block and the bundle payload. block and the bundle payload. The waypoint security
The waypoint security policy is to allow existing BIBs for these policy is to allow existing BIBs for these blocks to
blocks to persist, as they may be required as part of the security persist, as they may be required as part of the security
policy at the bundle destination. policy at the bundle destination.
</t> </t>
<t> <t>
The resultant bundle is illustrated in <xref target="bsp_ex2"/> The resultant bundle is illustrated in <xref target="bsp_ex2" format
="default"/>
and the security actions are described below. Note that block IDs and the security actions are described below. Note that block IDs
provided here are ordered solely for the purpose of this example provided here are ordered solely for the purpose of this example
and not meant to impose an ordering for block creation. The and are not meant to impose an ordering for block creation. The
ordering of blocks added to a bundle MUST always be in compliance ordering of blocks added to a bundle <bcp14>MUST</bcp14> always be i
with <xref target="I-D.ietf-dtn-bpbis"/>. n compliance
with <xref target="RFC9171" format="default"/>.
<figure anchor="bsp_ex2" title="Security At Bundle Forwarding"> </t>
<artwork align="center">&#xA;<!-- <figure anchor="bsp_ex2">
--> Block in Bundle ID&#xA;<!-- <name>Security at Bundle Forwarding</name>
-->+==========================================+====+&#xA;<!-- <artwork align="center" name="" type="" alt="">
-->| Primary Block | B1 |&#xA;<!-- Block in Bundle ID
-->+------------------------------------------+----+&#xA;<!-- +==========================================+====+
-->| BIB | B2 |&#xA;<!-- | Primary Block | B1 |
-->| OP(bib-integrity, targets=B1) | |&#xA;<!-- +------------------------------------------+----+
-->+------------------------------------------+----+&#xA;<!-- | BIB | B2 |
-->| BIB (encrypted) | B7 |&#xA;<!-- | OP(bib-integrity, target = B1) | |
-->| OP(bib-integrity, targets=B5, B6) | |&#xA;<!-- +------------------------------------------+----+
-->+------------------------------------------+----+&#xA;<!-- | BIB (encrypted) | B7 |
-->| BCB | B8 |&#xA;<!-- | OP(bib-integrity, targets = B5, B6) | |
-->| OP(bcb-confidentiality,targets=B5,B6,B7) | |&#xA;<!-- +------------------------------------------+----+
-->+------------------------------------------+----+&#xA;<!-- | BCB | B8 |
-->| BCB | B3 |&#xA;<!-- |OP(bcb-confidentiality,targets = B5,B6,B7)| |
-->| OP(bcb-confidentiality, target=B4) | |&#xA;<!-- +------------------------------------------+----+
-->+------------------------------------------+----+&#xA;<!-- | BCB | B3 |
-->| Extension Block (encrypted) | B4 |&#xA;<!-- | OP(bcb-confidentiality, target = B4) | |
-->+------------------------------------------+----+&#xA;<!-- +------------------------------------------+----+
-->| Extension Block (encrypted) | B5 |&#xA;<!-- | Extension Block (encrypted) | B4 |
-->+------------------------------------------+----+&#xA;<!-- +------------------------------------------+----+
-->| Payload Block (encrypted) | B6 |&#xA;<!-- | Extension Block (encrypted) | B5 |
-->+------------------------------------------+----+ +------------------------------------------+----+
</artwork> | Payload Block (encrypted) | B6 |
</figure> +------------------------------------------+----+</artwork>
</t> </figure>
<t> <t>
The following security actions were applied to this bundle prior to The following security actions were applied to this bundle prior to
its forwarding from the waypoint node. its forwarding from the waypoint node.
<list style="symbols"> </t>
<t> <ul spacing="normal">
<li>
Since the waypoint node wishes to encrypt the Since the waypoint node wishes to encrypt the
block-type-specific-data field of blocks B5 and B6, block-type-specific data field of blocks B5 and B6,
it MUST also encrypt the block-type-specific-data field of it <bcp14>MUST</bcp14> also encrypt the block-type-specific da
the BIBs providing plain text integrity ta field of
the BIBs providing plaintext integrity
over those blocks. However, BIB B2 could not be encrypted over those blocks. However, BIB B2 could not be encrypted
in its entirety because it also held a signature for the in its entirety because it also held a signature for the
primary block (B1). Therefore, a new BIB (B7) is created and primary block (B1). Therefore, a new BIB (B7) is created and
security results associated with B5 and B6 are moved out security results associated with B5 and B6 are moved out
of BIB B2 and into BIB B7. of BIB B2 and into BIB B7.
</t> </li>
<t> <li>
Now that there is no longer confusion of which plain text Now that there is no longer confusion about which plaintext
integrity signatures must be encrypted, a BCB is added to the integrity signatures must be encrypted, a BCB is added to the
bundle with the security targets being the second extension bundle with the security targets being the second extension
block (B5) and the payload (B6) as well as the newly created block (B5) and the payload (B6) as well as the newly created
BIB holding their plain text integrity signatures (B7). A BIB holding their plaintext integrity signatures (B7). A
single new BCB is used in this case because all three single new BCB is used in this case because all three
targets share a security source, security context, and targets share a security source, security context, and
security context parameters. Had this not been the case, security context parameters. Had this not been the case,
multiple BCBs could have been added instead. multiple BCBs could have been added instead.
</t> </li>
</list> </ul>
</t> </section>
</section> </section>
</section> </section>
<section anchor="CanonBundle" toc="default" numbered="true">
</section> <name>Canonical Forms</name>
<t>
<section anchor="CanonBundle" title="Canonical Forms" toc="default">
<t>
Security services require consistency and determinism in how information Security services require consistency and determinism in how information
is presented to cipher suites at security sources, verifiers, and acceptor s. is presented to cipher suites at security sources, verifiers, and acceptor s.
For example, integrity services require that the same target For example, integrity services require that the same target
information (e.g., the same bits in the same order) is provided to the information (e.g., the same bits in the same order) is provided to the
cipher suite when generating an original signature and when validating a cipher suite when generating an original signature and when validating a
signature. Canonicalization algorithms transcode the contents of a securit y signature. Canonicalization algorithms transcode the contents of a securit y
target into a canonical form. target into a canonical form.
</t> </t>
<t>
<t>
Canonical forms are used to generate input to a security context for Canonical forms are used to generate input to a security context for
security processing at a BP node. If the values of a security target are security processing at a BP node. If the values of a security target are
unchanged, then the canonical form of that target will be the same even unchanged, then the canonical form of that target will be the same even
if the encoding of those values for wire transmission is different. if the encoding of those values for wire transmission is different.
</t> </t>
<t>
<t>
BPSec operates on data fields within bundle blocks BPSec operates on data fields within bundle blocks
(e.g., the block-type-specific-data field). In their canonical form, these (e.g., the block-type-specific data field). In their canonical form, these
fields MUST include their own CBOR encoding and MUST NOT include any fields <bcp14>MUST</bcp14> include their own CBOR encoding and <bcp14>MUST
NOT</bcp14> include any
other encapsulating CBOR encoding. other encapsulating CBOR encoding.
For example, the canonical form of the block-type-specific-data field For example, the canonical form of the block-type-specific data field
is a CBOR byte string existing within the CBOR array containing the fields of is a CBOR byte string existing within the CBOR array containing the fields of
the extension block. The entire CBOR byte string is considered the canonic al the extension block. The entire CBOR byte string is considered the canonic al
block-type-specific-data field. The CBOR array block-type-specific data field. The CBOR array
framing is not considered part of the field. framing is not considered part of the field.
</t> </t>
<t>
<t> The canonical form of the primary block is as specified in <xref target="R
The canonical form of the primary block is as specified in <xref target="I FC9171" format="default"/> with
-D.ietf-dtn-bpbis"/> with
the following constraint. the following constraint.
<list style="symbols"> </t>
<t> <ul spacing="normal">
CBOR values from the primary block MUST be canonicalized using the r <li>
ules for Deterministically Encoded CBOR, CBOR values from the primary block <bcp14>MUST</bcp14> be canonicali
as specified in <xref target="RFC8949"/>. zed using the rules for Deterministically Encoded CBOR,
</t> as specified in <xref target="RFC8949" format="default"/>.
</list> </li>
</t> </ul>
<t>
<t>
All non-primary blocks share the same block structure and are All non-primary blocks share the same block structure and are
canonicalized as specified in <xref target="I-D.ietf-dtn-bpbis"/> with canonicalized as specified in <xref target="RFC9171" format="default"/> wi th
the following constraints. the following constraints.
<list style="symbols"> </t>
<t> <ul spacing="normal">
CBOR values from the non-primary block MUST be canonicalized using t <li>
he rules for Deterministically Encoded CBOR, CBOR values from the non-primary block <bcp14>MUST</bcp14> be canoni
as specified in <xref target="RFC8949"/>. calized using the rules for Deterministically Encoded CBOR,
</t> as specified in <xref target="RFC8949" format="default"/>.
<t> </li>
Only the block-type-specific-data field may be provided to a cipher <li>
suite for Only the block-type-specific data field may be provided to a cipher
encryption as part of a confidentiality security service. Other fiel suite for
ds within a non-primary-block encryption as part of a confidentiality security service. Other fiel
MUST NOT be encrypted or decrypted and MUST NOT be included in the c ds within a non-primary block
anonical form used by the <bcp14>MUST NOT</bcp14> be encrypted or decrypted and <bcp14>MUST NO
cipher suite for encryption and decryption. These other fields MAY h T</bcp14> be included in the canonical form used by the
ave an integrity protection cipher suite for encryption and decryption.
mechanism applied to them by treating them as associated authenticat An integrity-protection mechanism <bcp14>MAY</bcp14> be applied to these o
ed data. ther
</t> fields as supported by the security context. For example, these
<t> fields might be treated as associated authenticated data.
Reserved and unassigned flags in the block processing control flags </li>
field MUST be set to 0 in <li>
Reserved and unassigned flags in the block processing control flags
field <bcp14>MUST</bcp14> be set to 0 in
a canonical form as it is not known if those flags will change in tr ansit. a canonical form as it is not known if those flags will change in tr ansit.
</t> </li>
</list> </ul>
</t> <t>
Security contexts <bcp14>MAY</bcp14> define their own canonicalization alg
<t> orithms and require the use of those algorithms
Security contexts MAY define their own canonicalization algorithms and req
uire the use of those algorithms
over the ones provided in this specification. In the event of conflicting canonicalization algorithms, algorithms over the ones provided in this specification. In the event of conflicting canonicalization algorithms, algorithms
defined in a security context take precedence over this specification when constructing canonical forms for that defined in a security context take precedence over this specification when constructing canonical forms for that
security context. security context.
</t> </t>
</section> </section>
<section anchor="SecProc" toc="default" numbered="true">
<section anchor="SecProc" title="Security Processing" toc="default"> <name>Security Processing</name>
<t>
This section describes the security aspects of bundle processing.
</t>
<section anchor="BundleRX" title="Bundles Received from Other Nodes">
<t> <t>
This section describes the security aspects of bundle processing.
</t>
<section anchor="BundleRX" numbered="true" toc="default">
<name>Bundles Received from Other Nodes</name>
<t>
Security blocks must be processed in a specific order when received Security blocks must be processed in a specific order when received
by a BP node. The processing order is as follows. by a BP node. The processing order is as follows.
<list style="symbols"> </t>
<t> <ul spacing="normal">
When BIBs and BCBs share a security target, BCBs MUST be <li>
When BIBs and BCBs share a security target, BCBs <bcp14>MUST</bcp
14> be
evaluated first and BIBs second. evaluated first and BIBs second.
</t> </li>
</list> </ul>
</t> <section toc="default" numbered="true">
<name>Receiving BCBs</name>
<section title="Receiving BCBs" toc="default"> <t>
<t> If a received bundle contains a BCB, the receiving node <bcp14>MUST<
If a received bundle contains a BCB, the receiving node MUST /bcp14>
determine whether it is the security acceptor for any of determine whether it is the security acceptor for any of
the security operations in the BCB. If so, the node MUST the security operations in the BCB. If so, the node <bcp14>MUST</bcp 14>
process those operations and remove any operation-specific process those operations and remove any operation-specific
information from the BCB prior to delivering data to an application at the node information from the BCB prior to delivering data to an application at the node
or forwarding the bundle. If processing a security operation fails, or forwarding the bundle. If processing a security operation fails,
the target SHALL be processed according to the security policy. the target <bcp14>SHALL</bcp14> be processed according to the securi
A bundle status report indicating the failure MAY be generated. ty policy.
A bundle status report indicating the failure <bcp14>MAY</bcp14> be
generated.
When all security operations for a BCB have been removed from When all security operations for a BCB have been removed from
the BCB, the BCB MUST be removed from the bundle. the BCB, the BCB <bcp14>MUST</bcp14> be removed from the bundle.
</t> </t>
<t>
<t> If the receiving node is the destination of the bundle,
If the receiving node is the destination of the bundle, the node the node <bcp14>MUST</bcp14> decrypt any BCBs remaining in
MUST decrypt any BCBs remaining in the bundle. If the receiving the bundle. If the receiving node is not the destination
node is not the destination of the bundle, the node MUST process of the bundle, the node <bcp14>MUST</bcp14> process the
the BCB if directed to do so as a matter of security policy. BCB if directed to do so as a matter of security policy.
</t> </t>
<t>
<t> If the security policy of a node specifies that a node
If the security policy of a node specifies that a should have applied confidentiality to a specific security
node should have applied confidentiality to a specific security target and no such BCB is present in the bundle, then the
target and no such BCB is present in the bundle, then the node node <bcp14>MUST</bcp14> process this security target in
MUST process this security target in accordance with the security accordance with the security policy. It is
policy. It is RECOMMENDED that the node remove the security target <bcp14>RECOMMENDED</bcp14> that the node remove the
from the bundle because the confidentiality (and possibly the integr security target from the bundle because the
ity) confidentiality (and possibly the integrity) of the
of the security target cannot be guaranteed. If the removed security security target cannot be guaranteed. If the removed
target security target is the payload block, the bundle
is the payload block, the bundle MUST be discarded. <bcp14>MUST</bcp14> be discarded.
</t> </t>
<t>
<t> If an encrypted payload block cannot be decrypted (i.e.,
If an encrypted payload block cannot be decrypted (i.e., the the ciphertext cannot be authenticated), then the bundle
cipher text cannot be authenticated), then the bundle MUST be <bcp14>MUST</bcp14> be discarded and processed no
discarded and processed no further. If an encrypted security further. If an encrypted security target other than the
target other than the payload block cannot be decrypted then the payload block cannot be decrypted, then the associated
associated security target and all security blocks associated with security target and all security blocks associated with
that target MUST be discarded and processed no further. In both that target <bcp14>MUST</bcp14> be discarded and processed
cases, requested status reports (see no further. In both cases, requested status reports (see
<xref target="I-D.ietf-dtn-bpbis"/>) MAY be generated to reflect <xref target="RFC9171" format="default"/>)
bundle or block deletion. <bcp14>MAY</bcp14> be generated to reflect bundle or block
</t> deletion.
</t>
<t> <t>
When a BCB is decrypted, the recovered plain text for each When a BCB is decrypted, the recovered plaintext for each
security target MUST replace the cipher text in each of the security target <bcp14>MUST</bcp14> replace the ciphertext in each o
security targets' block-type-specific-data fields. If the f the
plain text is of different size than the cipher text, the CBOR byte security targets' block-type-specific data fields. If the
string framing of this field must be updated to ensure this field plaintext is of a different size than the ciphertext, the framing of
remains a valid CBOR byte string. The length of the recovered plain the CBOR byte
text is known by the decrypting security context. string of this field must be updated to ensure this field
</t> remains a valid CBOR byte string. The length of the recovered plaint
ext
<t> is known by the decrypting security context.
</t>
<t>
If a BCB contains multiple security operations, each operation proce ssed If a BCB contains multiple security operations, each operation proce ssed
by the node MUST be treated as if the security operation by the node <bcp14>MUST</bcp14> be treated as if the security operat ion
has been represented by a single BCB with a single has been represented by a single BCB with a single
security operation for the purposes of report generation and policy security operation for the purposes of report generation and policy
processing. processing.
</t> </t>
</section>
</section> <section toc="default" numbered="true">
<name>Receiving BIBs</name>
<section title="Receiving BIBs" toc="default"> <t>
If a received bundle contains a BIB, the receiving node
<t> <bcp14>MUST</bcp14> determine whether it is the security
If a received bundle contains a BIB, the receiving node MUST acceptor for any of the security operations in the BIB. If
determine whether it is the security acceptor for any of so, the node <bcp14>MUST</bcp14> process those operations
the security operations in the BIB. If so, the node MUST process and remove any operation-specific information from the BIB
those operations and remove any operation-specific information prior to delivering data to an application at the node or
from the BIB prior to delivering data to an application at the node forwarding the bundle. If processing a security operation
or forwarding the bundle. If processing a security operation fails, fails, the target <bcp14>SHALL</bcp14> be processed
the target SHALL be processed according to the security policy. A according to the security policy. A bundle status report
bundle status report indicating the failure MAY be generated. When indicating the failure <bcp14>MAY</bcp14> be
all security operations for a BIB have been removed from the BIB, generated. When all security operations for a BIB have
the BIB MUST be removed from the bundle. been removed from the BIB, the BIB <bcp14>MUST</bcp14> be
</t> removed from the bundle.
</t>
<t> <t>
A BIB MUST NOT be processed if the security target of the BIB is A BIB <bcp14>MUST NOT</bcp14> be processed if the security
also the security target of a BCB in the bundle. Given the order of target of the BIB is also the security target of a BCB in
operations mandated by this specification, when both a BIB and a the bundle. Given the order of operations mandated by this
BCB share a security target, it means that the security target specification, when both a BIB and a BCB share a security
must have been encrypted after it was integrity signed and, target, it means that the security target must have been
therefore, the BIB cannot be verified until the security target encrypted after it was integrity signed; therefore, the
has been decrypted by processing the BCB. BIB cannot be verified until the security target has been
</t> decrypted by processing the BCB.
</t>
<t> <t>
If the security policy of a node specifies that a If the security policy of a node specifies that a node
node should have applied integrity to a specific security target should have applied integrity to a specific security
and no such BIB is present in the bundle, then the node MUST target and no such BIB is present in the bundle, then the
process this security target in accordance with the security node <bcp14>MUST</bcp14> process this security target in
policy. It is RECOMMENDED that the node remove the security accordance with the security policy. It is
target from the bundle if the security target is not the <bcp14>RECOMMENDED</bcp14> that the node remove the
payload or primary block. If the security target is security target from the bundle if the security target is
the payload or primary block, the bundle MAY be not the payload or primary block. If the security target
discarded. This action can occur at any node that has the is the payload or primary block, the bundle
ability to verify an integrity signature, not just the bundle destin <bcp14>MAY</bcp14> be discarded. This action can occur at
ation. any node that has the ability to verify an integrity
</t> signature, not just the bundle destination.
</t>
<t> <t>
If a receiving node is not the security acceptor of a security If a receiving node is not the security acceptor of a
operation in a BIB it MAY attempt to verify the security operation security operation in a BIB, it <bcp14>MAY</bcp14> attempt
anyway to prevent forwarding corrupt data. If the verification fails to verify the security operation anyway to prevent
, the forwarding corrupt data. If the verification fails, the
node SHALL process the security target in accordance to local node <bcp14>SHALL</bcp14> process the security target in
security policy. It is RECOMMENDED that if a payload integrity accordance with local security policy.
check fails at a waypoint that it is processed in the same way as If a payload integrity check fails at a waypoint, it is
if the check fails at the bundle destination. If the check passes, t <bcp14>RECOMMENDED</bcp14> that it be processed in the
he same way as a failure of a payload
node MUST NOT remove the security operation from the BIB prior to fo integrity check at the bundle destination. If
rwarding. the check passes, the node <bcp14>MUST NOT</bcp14> remove
</t> the security operation from the BIB prior to forwarding.
</t>
<t> <t>
If a BIB contains multiple security operations, each operation proce ssed If a BIB contains multiple security operations, each operation proce ssed
by the node MUST be treated as if the security operation by the node <bcp14>MUST</bcp14> be treated as if the security operat ion
has been represented by a single BIB with a single has been represented by a single BIB with a single
security operation for the purposes of report generation and policy security operation for the purposes of report generation and policy
processing. processing.
</t> </t>
</section>
</section> </section>
</section> <section anchor="FragRe" numbered="true" toc="default">
<name>Bundle Fragmentation and Reassembly</name>
<section anchor="FragRe" title="Bundle Fragmentation and Reassembly"> <t>
<t>
If it is necessary for a node to fragment a bundle payload, and If it is necessary for a node to fragment a bundle payload, and
security services have been applied to that bundle, the fragmentation security services have been applied to that bundle, the fragmentation
rules described in <xref target="I-D.ietf-dtn-bpbis"/> MUST be rules described in <xref target="RFC9171" format="default"/> <bcp14>MUS T</bcp14> be
followed. As defined there and summarized here for completeness, only followed. As defined there and summarized here for completeness, only
the payload block can be fragmented; security blocks, like all the payload block can be fragmented; security blocks, like all
extension blocks, can never be fragmented. extension blocks, can never be fragmented.
</t> </t>
<t>
<t> Due to the complexity of payload-block fragmentation, including the
Due to the complexity of payload block fragmentation, including the possibility of fragmenting payload-block fragments, integrity and
possibility of fragmenting payload block fragments, integrity and
confidentiality operations are not to be applied to a bundle confidentiality operations are not to be applied to a bundle
representing a fragment. Specifically, a BCB or BIB MUST NOT be representing a fragment. Specifically, a BCB or BIB <bcp14>MUST NOT</bc
added to a bundle if the "Bundle is a Fragment" flag is set in the p14> be
Bundle Processing Control Flags field. added to a bundle if the "Bundle is a fragment" flag is set in the
</t> bundle processing control flags field.
</t>
<t> <t>
Security processing in the presence of payload block fragmentation may Security processing in the presence of payload-block fragmentation may
be handled by other mechanisms outside of the BPSec protocol or be handled by other mechanisms outside of the BPSec protocol or
by applying BPSec blocks in coordination with an encapsulation by applying BPSec blocks in coordination with an encapsulation
mechanism. A node should apply any confidentiality mechanism. A node should apply any confidentiality
protection prior to performing any fragmentation. protection prior to performing any fragmentation.
</t>
</section>
</section>
<section anchor="KeyMgmt" toc="default" numbered="true">
<name>Key Management</name>
<t>
There exists a myriad of ways to establish, communicate, and
otherwise manage key information in DTN. Certain DTN
deployments might follow established protocols for key
management, whereas other DTN deployments might require new and
novel approaches. BPSec assumes that key management is handled
as a separate part of network management; this specification
neither defines nor requires a specific strategy for key management.
</t> </t>
</section> </section>
</section> <section anchor="PolCons" toc="default" numbered="true">
<name>Security Policy Considerations</name>
<section anchor="KeyMgmt" title="Key Management" toc="default"> <t>
<t>
There exist a myriad of ways to establish, communicate, and otherwise
manage key information in a DTN. Certain DTN deployments might follow
established protocols for key management whereas other DTN deployments
might require new and novel approaches. BPSec assumes that key
management is handled as a separate part of network management and this
specification neither defines nor requires a specific key management
strategy.
</t>
</section>
<section anchor="PolCons" title="Security Policy Considerations" toc="default">
<t>
When implementing BPSec, several policy decisions must be When implementing BPSec, several policy decisions must be
considered. This section describes key policies that affect the considered. This section describes key policies that affect the
generation, forwarding, and receipt of bundles that are secured using generation, forwarding, and receipt of bundles that are secured using
this specification. No single set of policy decisions is envisioned to this specification. No single set of policy decisions is envisioned to
work for all secure DTN deployments. work for all secure DTN deployments.
<list style="symbols"> </t>
<t> <ul spacing="normal">
<li>
If a bundle is received that contains combinations of If a bundle is received that contains combinations of
security operations that are disallowed by this specification the BP security operations that are disallowed by this
A must specification, the BPA must determine how to handle the
determine how to handle the bundle. The bundle may be discarded, bundle: the bundle may be discarded, the block affected by
the block affected by the security operation may be discarded, or the security operation may be discarded, or one security
one security operation may be favored over another. operation may be favored over another.
</t> </li>
<li>
<t>
BPAs in the network must understand what security operations they BPAs in the network must understand what security operations they
should apply to bundles. This decision may be based on the source should apply to bundles. This decision may be based on the source
of the bundle, the destination of the bundle, or some other of the bundle, the destination of the bundle, or some other
information related to the bundle. information related to the bundle.
</t> </li>
<li>
<t> If a waypoint has been configured to add a security
If a waypoint has been configured to add a operation to a bundle, and the received bundle already has
security operation to a bundle, and the received bundle already has the security operation applied, then the receiver must
the security operation applied, then the receiver must understand understand what to do. The receiver may discard the
what to do. The receiver may discard the bundle, discard the bundle, discard the security target and associated BPSec
security target and associated BPSec blocks, replace the blocks, replace the security operation, or take some other
security operation, or some other action. action.
</t> </li>
<li>
<t> It is <bcp14>RECOMMENDED</bcp14> that security operations
It is RECOMMENDED that security operations be applied to every be applied to every block in a bundle and that the default
block in a bundle and that the default behavior of a bundle agent is behavior of a BPA be to use the security services
to use the security services defined in this specification. Designer defined in this specification. Designers should only
s deviate from the use of security operations when the
should only deviate from the use of security operations when the dev deviation can be justified -- such as when doing so causes
iation downstream errors when processing blocks whose contents
can be justified - such as when doing so causes must be inspected or changed at one or more hops along the
downstream errors when processing blocks whose contents must be path.
inspected or changed at one or more hops along the path. </li>
</t> <li>
BCB security contexts can alter the size of extension
<t> blocks and the payload block. Security policy
BCB security contexts can alter the size of extension blocks and the <bcp14>SHOULD</bcp14> consider how changes to the size of
payload block. Security policy SHOULD consider how changes to the si a block could negatively effect bundle processing (e.g.,
ze calculating storage needs and scheduling transmission
of a block could negatively effect bundle processing (e.g., times).
calculating storage needs and scheduling transmission times). </li>
</t> <li>
<t>
<t>
Adding a BIB to a security target that has already been encrypted Adding a BIB to a security target that has already been encrypted
by a BCB is not allowed. If this condition is likely to be by a BCB is not allowed. If this condition is likely to be
encountered, there are (at least) three possible policies that encountered, there are (at least) three possible policies that
could handle this situation. could handle this situation.
<list style="numbers"> </t>
<t> <ol spacing="normal" type="1"><li>
At the time of encryption, a security context can be At the time of encryption, a security context can be
selected which computes a plain text integrity-protection mech anism selected that computes a plaintext integrity-protection mechan ism
that is included as a security context result field. that is included as a security context result field.
</t> </li>
<t> <li>
The encrypted block may be replicated as a new block with The encrypted block may be replicated as a new block with
a new block number and given integrity protection. a new block number and may be given integrity protection.
</t> </li>
<t> <li>
An encapsulation scheme may be applied to encapsulate the An encapsulation scheme may be applied to encapsulate the
security target (or the entire bundle) such that the security target (or the entire bundle) such that the
encapsulating structure is, itself, no longer the security encapsulating structure is, itself, no longer the security
target of a BCB and may therefore be the security target of target of a BCB and may therefore be the security target of
a BIB. a BIB.
</t> </li>
</list> </ol>
</t> </li>
<li>
<t> Security policy <bcp14>SHOULD</bcp14> address whether cipher
Security policy SHOULD address whether cipher suites whose ciphertext is larger than the initial
suites whose cipher text is larger than the initial plaintext are permitted and, if so, for what types of blocks.
plain text are permitted and, if so, for what types of blocks.
Changing the size of a block may cause processing difficulties for Changing the size of a block may cause processing difficulties for
networks that calculate block offsets into bundles or predict networks that calculate block offsets into bundles or predict
transmission times or storage availability as a function of bundle transmission times or storage availability as a function of bundle
size. In other cases, changing the size of a payload as part of size. In other cases, changing the size of a payload as part of
encryption has no significant impact. encryption has no significant impact.
</t> </li>
</list> </ul>
</t> <section anchor="ReasonCodes" numbered="true" toc="default">
<section anchor="ReasonCodes" title="Security Reason Codes"> <name>Security Reason Codes</name>
<t> <t>
Bundle protocol agents (BPAs) must process blocks and bundles in BPAs must process blocks and bundles in
accordance with both BP policy and BPSec policy. The decision to accordance with both BP policy and BPSec policy. The decision to
receive, forward, deliver, or delete a bundle may be communicated to receive, forward, deliver, or delete a bundle may be communicated to
the report-to address of the bundle, in the form of a status report, the report-to address of the bundle in the form of a status report,
as a method of tracking the progress of the bundle through the as a method of tracking the progress of the bundle through the
network. The status report for a bundle may be augmented with a network. The status report for a bundle may be augmented with a
"reason code" explaining why the particular action was taken on the "reason code" explaining why the particular action was taken on the
bundle. bundle.
</t> </t>
<t>
<t>
This section describes a set of reason codes associated with the This section describes a set of reason codes associated with the
security processing of a bundle. The communication of security-related security processing of a bundle. The communication of security-related
status reports might reduce the security of a network if these reports status reports might reduce the security of a network if these reports
are intercepted by unintended recipients. BPSec policy SHOULD specify are intercepted by unintended recipients. BPSec policy <bcp14>SHOULD</b cp14> specify
the conditions in which sending security reason codes are appropriate. the conditions in which sending security reason codes are appropriate.
Examples of appropriate conditions for the use of security reason codes Examples of appropriate conditions for the use of security reason codes
could include the following. could include the following.
<list style="symbols"> </t>
<t> <ul spacing="normal">
When the report-to address is verified as unchanged from the bund <li>
le source. When the report-to address is verified as unchanged
This can occur by placing an appropriate BIB on the bundle primar from the bundle source. This can occur by placing an
y appropriate BIB on the bundle primary block.
block. </li>
</t> <li>
<t> When the block containing a status report with a
When the block containing a status report with a security reason security reason code is encrypted by a BCB.
code </li>
is encrypted by a BCB. <li>
</t> When a status report containing a security reason code
<t> is only sent for security issues relating to bundles
When a status report containing a security reason code is only se and/or blocks associated with non-operational user data
nt for or test data.
security issues relating to bundles and/or blocks associated </li>
with non-operational user data or otherwise with test data. <li>
</t> When a status report containing a security reason code
<t> is only sent for security issues associated with
When a status report containing a security reason code is only se non-operational security contexts, or security contexts
nt for using non-operational configurations, such as test
security issues associated with non-operational security contexts keys.
, or </li>
security contexts using non-operational configurations, such as t </ul>
est keys. <t>
</t> Security reason codes are assigned in accordance with <xref
</list> target="secreasoncode" format="default"/> and are as
</t> described below.
<t>
Security reason codes are assigned in accordance with
<xref target="secreasoncode"/> and are as described below.
<list style="hanging" hangIndent="6">
<t hangText="Missing Security Operation:"> <vspace/>
This reason code indicates that a bundle was missing one or
more required security operations. This reason code is typically
used by a security verifier or security acceptor.
</t>
<t hangText="Unknown Security Operation:"> <vspace/>
This reason code indicates that one or more security operations
present in a bundle cannot be understood by the security verifier
or
security acceptor for the operation. For example, this reason co
de may be used if
a security block references an unknown security context identifie
r
or security context parameter. This reason code should not be use
d
for security operations for which the node is not a security veri
fier
or security acceptor; there is no requirement that all nodes in
a network understand all security contexts, security context
parameters, and security services for every bundle in a network.
</t>
<t hangText="Unexpected Security Operation:"> <vspace/> </t>
<dl newline="true" spacing="normal" indent="6">
<dt>Missing security operation:</dt>
<dd>
This reason code indicates that a bundle was missing
one or more required security operations. This reason
code is typically used by a security verifier or
security acceptor.
</dd>
<dt>Unknown security operation:</dt>
<dd>
This reason code indicates that one or more security
operations present in a bundle cannot be understood by
the security verifier or security acceptor for the
operation. For example, this reason code may be used
if a security block references an unknown security
context identifier or security context parameter. This
reason code should not be used for security operations
for which the node is not a security verifier or
security acceptor; there is no requirement that all
nodes in a network understand all security contexts,
security context parameters, and security services for
every bundle in a network.
</dd>
<dt>Unexpected security operation:</dt>
<dd>
This reason code indicates that a receiving node is neither a This reason code indicates that a receiving node is neither a
security verifier nor a security acceptor for at least one security verifier nor a security acceptor for at least one
security operation in a bundle. This reason code should not security operation in a bundle. This reason code should not
be seen as an error condition; not every node is a security be seen as an error condition: not every node is a security
verifier or security acceptor for every security operation in verifier or security acceptor for every security operation in
every bundle. In certain networks, this reason code may be every bundle. In certain networks, this reason code may be
useful in identifying misconfigurations of security policy. useful in identifying misconfigurations of security policy.
</t> </dd>
<dt>Failed security operation:</dt>
<t hangText="Failed Security Operation:"> <vspace/> <dd>
This reason code indicates that one or more security operations i This reason code indicates that one or more security
n operations in a bundle failed to process as expected
a bundle failed to process as expected for reasons other than for reasons other than misconfiguration. This may occur
misconfiguration. This may occur when a security-source is unable when a security-source is unable to add a security
to add a block to a bundle. This may occur if the target of a
security block to a bundle. This may occur if the target of a se security operation fails to verify using the defined
curity security context at a security verifier. This may also
operation fails to verify using the defined security context at a occur if a security operation fails to be processed
security verifier. without error at a security acceptor.
This may also occur if a security operation fails to be processed </dd>
without error at <dt>Conflicting security operation:</dt>
a security acceptor. <dd>
</t> This reason code indicates that two or more security
operations in a bundle are not conformant with the
<t hangText="Conflicting Security Operations:"> <vspace/> BPSec specification and that security processing was
This reason code indicates that two or more security operations i unable to proceed because of a BPSec protocol
n a bundle violation.
are not conformant with the BPSec specification and that security </dd>
processing </dl>
was unable to proceed because of a BPSec protocol violation. </section>
</t> </section>
</list> <section anchor="SecCons" toc="default" numbered="true">
</t> <name>Security Considerations</name>
</section>
</section>
<section anchor="SecCons" title="Security Considerations" toc="default">
<t>
Given the nature of DTN applications, it is
expected that bundles may traverse a variety of environments and devices
which each pose unique security risks and requirements on the
implementation of security within BPSec. For these reasons, it is
important to introduce key threat models and describe the roles and
responsibilities of the BPSec protocol in protecting the confidentiality
and integrity of the data against those threats. This section provides
additional discussion on security threats that BPSec will face and
describes how BPSec security mechanisms operate to mitigate these
threats.
</t>
<t>
The threat model described here is assumed to have a set of capabilities
identical to those described by the Internet Threat Model in
<xref target="RFC3552"/>, but the BPSec threat model is scoped to
illustrate threats specific to BPSec operating within DTN environments
and therefore focuses on on-path-attackers (OPAs). In doing
so, it is assumed that the DTN (or significant portions of the DTN) are
completely under the control of an attacker.
</t>
<section anchor="SecConsAttack" title="Attacker Capabilities and Objectives">
<t>
BPSec was designed to protect against OPA threats which may have access
to a
bundle during transit from its source, Alice, to its destination, Bob.
An OPA node,
Olive, is a non-cooperative node operating on the DTN between Alice and
Bob that
has the ability to receive bundles, examine bundles, modify bundles, fo
rward bundles,
and generate bundles at will in order to compromise the confidentiality
or integrity
of data within the DTN. There are three classes of OPA nodes which are
differentiated based
on their access to cryptographic material:
<list style="symbols">
<t>
Unprivileged Node: Olive has not been provisioned within the secu
re environment and
only has access to cryptographic material which has been publicly
-shared.
</t>
<t>
Legitimate Node: Olive is within the secure environment and there
fore has
access to cryptographic material which has been provisioned to Ol
ive (i.e., K_M)
as well as material which has been publicly-shared.
</t>
<t>
Privileged Node: Olive is a privileged node within the secure env
ironment
and therefore has access to cryptographic material which has been
provisioned to
Olive, Alice and/or Bob (i.e. K_M, K_A, and/or K_B) as well as ma
terial which
has been publicly-shared.
</t>
</list>
</t>
<t> <t>
If Olive is operating as a privileged node, this is tantamount to compr Given the nature of DTN applications, it is expected that
omise; bundles may traverse a variety of environments and devices that
BPSec does not provide mechanisms to detect or remove Olive from the DT each pose unique security risks and requirements on the
N or implementation of security within BPSec. For this reason, it
BPSec secure environment. It is up to the BPSec implementer or the und is important to introduce key threat models and describe the
erlying roles and responsibilities of the BPSec protocol in protecting
cryptographic mechanisms to provide appropriate capabilities if they ar the confidentiality and integrity of the data against those
e needed. threats. This section provides additional discussion on security
It should also be noted that if the implementation of BPSec uses a sing threats that BPSec will face and describes how BPSec security
le set of mechanisms operate to mitigate these threats.
shared cryptographic material for all nodes, a legitimate node is equiv
alent to a
privileged node because K_M == K_A == K_B. For this reason, sharing cry
ptographic
material in this way is not recommended.
</t> </t>
<t> <t>
A special case of the legitimate node is when Olive is either Alice or The threat model described here is assumed to have a set of
Bob capabilities identical to those described by the Internet Threat
(i.e., K_M == K_A or K_M == K_B). In this case, Olive is able to imper Model in <xref target="RFC3552" format="default"/>, but the
sonate BPSec threat model is scoped to illustrate threats specific to
traffic as either Alice or Bob, respectively, which means that traffic BPSec operating within DTN environments; therefore, it focuses on
to and from that node can be on-path attackers (OPAs). In doing so, it is assumed that the
decrypted and encrypted, respectively. Additionally, messages may be s delay-tolerant network (or significant portions of the delay-tolerant netw
igned as ork) are completely under
originating from one of the endpoints. the control of an attacker.
</t> </t>
</section> <section anchor="SecConsAttack" numbered="true" toc="default">
<name>Attacker Capabilities and Objectives</name>
<section anchor="SecConsBehave" title="Attacker Behaviors and BPSec Mitigatio <t>
ns" toc="default"> BPSec was designed to protect against OPA threats that may
have access to a bundle during transit from its source,
<section title="Eavesdropping Attacks" toc="default"> Alice, to its destination, Bob.
<t> An OPA node, Olive, is a
Once Olive has received a bundle, she is able to examine the content noncooperative node operating on the delay-tolerant network between Ali
s of that ce and
bundle and attempt to recover any protected data or cryptographic ke Bob that has the ability to receive bundles, examine bundles,
ying material modify bundles, forward bundles, and generate bundles at will
from the blocks contained within. The protection mechanism that BPS in order to compromise the confidentiality or integrity of
ec provides against data within the delay-tolerant network. There are three classes of OPA
this action is the BCB, which encrypts the contents of its security nodes
target, providing that are differentiated based on their access to
confidentiality of the data. Of course, it should be assumed that O cryptographic material:
live is able to
attempt offline recovery of encrypted data, so the cryptographic mec
hanisms selected
to protect the data should provide a suitable level of protection.
</t>
<t>
When evaluating the risk of eavesdropping attacks, it is important t
o consider the lifetime
of bundles on a DTN. Depending on the network, bundles may persist
for days or even years.
Long-lived bundles imply that the data exists in the network for a l
onger period of time and,
thus, there may be more opportunities to capture those bundles. Addi
tionally, bundles that
are long-lived imply that the information stored within them may rem
ain relevant and sensitive
for long enough that, once captured, there is sufficient time to cra
ck encryption associated
with the bundle. If a bundle does persist on the network for years a
nd the cipher suite used for a BCB provides inadequate protection, Olive may be
able to recover the protected data either before that bundle reaches its intende
d destination or before the information in the bundle is no longer considered se
nsitive.
</t>
<t>
NOTE: Olive is not limited by the bundle lifetime and may retain a g
iven bundle indefinitely.
</t>
<t>
NOTE: Irrespective of whether BPSec is used, traffic analysis will b
e possible.
</t>
</section>
<section title="Modification Attacks" toc="default">
<t>
As a node participating in the DTN between Alice and Bob, Olive will
also be
able to modify the received bundle, including non-BPSec data such as
the primary
block, payload blocks, or block processing control flags as defined
in <xref target="I-D.ietf-dtn-bpbis"/>. Olive
will be able to undertake activities which include modification of d
ata within the blocks,
replacement of blocks, addition of blocks, or removal of blocks. Wi
thin BPSec, both the BIB
and BCB provide integrity protection mechanisms to detect or prevent
data manipulation
attempts by Olive.
</t>
<t>
The BIB provides that protection to another block which is its secur
ity target. The
cryptographic mechanisms used to generate the BIB should be strong a
gainst collision attacks
and Olive should not have access to the cryptographic material used
by the originating node
to generate the BIB (e.g., K_A). If both of these conditions are tr
ue, Olive will be unable
to modify the security target or the BIB and lead Bob to validate th
e security target as
originating from Alice.
</t>
<t>
Since BPSec security operations are implemented by placing blocks in
a bundle, there
is no in-band mechanism for detecting or correcting certain cases wh
ere Olive removes
blocks from a bundle. If Olive removes a BCB, but keeps the security
target, the
security target remains encrypted and there is a possibility that th
ere may no longer be
sufficient information to decrypt the block at its destination. If
Olive removes both a
BCB (or BIB) and its security target there is no evidence left in th
e bundle of the security
operation. Similarly, if Olive removes the BIB but not the security
target there is
no evidence left in the bundle of the security operation. In each o
f these cases, the
implementation of BPSec must be combined with policy configuration a
t endpoints in the
network which describe the expected and required security operations
that must be applied
on transmission and are expected to be present on receipt. This or
other similar
out-of-band information is required to correct for removal of securi
ty information in the
bundle.
</t>
<t>
A limitation of the BIB may exist within the implementation of BIB v
alidation at the destination
node. If Olive is a legitimate node within the DTN, the BIB generat
ed by Alice with K_A can be
replaced with a new BIB generated with K_M and forwarded to Bob. If
Bob is only validating
that the BIB was generated by a legitimate user, Bob will acknowledg
e the message as originating
from Olive instead of Alice. Validating a BIB indicates only that th
e BIB was generated
by a holder of the relevant key; it does not provide any guarantee t
hat the bundle or block was created by the same entity. In order to provide veri
fiable integrity checks BCB should require
an encryption scheme that is Indistinguishable under adaptive Chosen
Ciphertext Attack (IND-CCA2) secure. Such an encryption scheme
will guard against signature substitution attempts by Olive. In this
case, Alice creates a BIB
with the protected data block as the security target and then
creates a BCB with both the BIB and protected data block as its secu
rity targets.
</t>
</section>
<section anchor="SecConsTopAtck" title="Topology Attacks" toc="default">
<t>
If Olive is in a OPA position within the DTN, she is able to influe
nce how any
bundles that come to her may pass through the network. Upon receivi
ng and processing a
bundle that must be routed elsewhere in the network, Olive has three
options as to how
to proceed: not forward the bundle, forward the bundle as intended,
or forward the bundle
to one or more specific nodes within the network.
</t>
<t>
Attacks that involve re-routing the packets throughout the network a
re essentially a special
case of the modification attacks described in this section where the
attacker is modifying
fields within the primary block of the bundle. Given that BPSec can
not encrypt the contents
of the primary block, alternate methods must be used to prevent this
situation. These methods
may include requiring BIBs for primary blocks, using encapsulation,
or otherwise strategically
manipulating primary block data. The specifics of any such mitigatio
n technique
are specific to the implementation of the deploying network and outs
ide of the scope of this
document.
</t>
<t> </t>
Furthermore, routing rules and policies may be useful in enforcing p <dl spacing="normal">
articular traffic flows <dt>Unprivileged Node:</dt><dd>Olive has not been provisioned
to prevent topology attacks. While these rules and policies may uti within the secure environment and only has access to
lize some features cryptographic material that has been publicly shared.
provided by BPSec, their definition is beyond the scope of this spec </dd>
ification. <dt>Legitimate Node:</dt><dd>Olive is within the secure environment;
</t> therefore, Olive has access to cryptographic material
that has been provisioned to Olive (i.e., K<sub>M</sub>) as well
as material that has been publicly shared.
</dd>
<dt>Privileged Node:</dt><dd>Olive is a privileged node within the
secure environment; therefore, Olive has access to
cryptographic material that has been provisioned to
Olive, Alice, and/or Bob (i.e., K<sub>M</sub>, K<sub>A</sub>, and
/or K<sub>B</sub>) as
well as material that has been publicly shared.
</dd>
</dl>
<t>
If Olive is operating as a privileged node, this is
tantamount to compromise; BPSec does not provide mechanisms
to detect or remove Olive from the delay-tolerant network or BPSec secu
re
environment. It is up to the BPSec implementer or the
underlying cryptographic mechanisms to provide appropriate
capabilities if they are needed. It should also be noted
that if the implementation of BPSec uses a single set of
shared cryptographic material for all nodes, a legitimate
node is equivalent to a privileged node because K<sub>M</sub> == K<sub>
A</sub> ==
K<sub>B</sub>. For this reason, sharing cryptographic material in this
way is not recommended.
</t>
<t>
A special case of the legitimate node is when Olive is either
Alice or Bob (i.e., K<sub>M</sub> == K<sub>A</sub> or K<sub>M</sub> ==
K<sub>B</sub>). In this case,
Olive is able to impersonate traffic as either Alice or Bob,
respectively, which means that traffic to and from that node
can be decrypted and encrypted, respectively. Additionally,
messages may be signed as originating from one of the
endpoints.
</t>
</section> </section>
<section anchor="SecConsBehave" toc="default" numbered="true">
<section title="Message Injection" toc="default"> <name>Attacker Behaviors and BPSec Mitigations</name>
<t> <section toc="default" numbered="true">
Olive is also able to generate new bundles and transmit them into th <name>Eavesdropping Attacks</name>
e DTN at will. <t>
These bundles may either be copies or slight modifications of previo Once Olive has received a bundle, she is able to examine
usly-observed bundles the contents of that bundle and attempt to recover any
(i.e., a replay attack) or entirely new bundles generated based on t protected data or cryptographic keying material from the
he Bundle Protocol, blocks contained within. The protection mechanism that
BPSec, or other bundle-related protocols. With these attacks Olive' BPSec provides against this action is the BCB, which
s objectives may encrypts the contents of its security target, providing
vary, but may be targeting either the bundle protocol or application confidentiality of the data. Of course, it should be
-layer protocols conveyed assumed that Olive is able to attempt offline recovery of
by the bundle protocol. The target could also be the storage and com encrypted data, so the cryptographic mechanisms selected
pute of the nodes running to protect the data should provide a suitable level of
the bundle or application layer protocols (e.g., a denial of service protection.
to flood on the </t>
storage of the store-and-forward mechanism; or compute which would p <t>
rocess the packets and When evaluating the risk of eavesdropping attacks, it is
perhaps prevent other activities). important to consider the lifetime of bundles on DTN.
</t> Depending on the network, bundles may persist for days or
even years. Long-lived bundles imply that the data exists
<t> in the network for a longer period of time and, thus,
BPSec relies on cipher suite capabilities to prevent replay or forge there may be more opportunities to capture those
d message attacks. bundles. Additionally, the implication is that long-lived bundles st
A BCB used with appropriate cryptographic mechanisms may provide rep ore information within that remains relevant and sensitive for long enough that,
lay protection once
under certain circumstances. Alternatively, captured, there is sufficient time to crack encryption
application data itself may be augmented to include mechanisms to as associated with the bundle. If a bundle does persist on
sert data uniqueness the network for years and the cipher suite used for a BCB
and then protected with a BIB, a BCB, or both along with other block provides inadequate protection, Olive may be able to
data. In recover the protected data either before that bundle
such a case, the receiving node would be able to validate the unique reaches its intended destination or before the information
ness of the data. in the bundle is no longer considered sensitive.
</t> </t>
<t> <t>
For example, a BIB may be used to validate the integrity of a bundle NOTE: Olive is not limited by the bundle lifetime and may
's primary block, retain a given bundle indefinitely.
which includes a timestamp and lifetime for the bundle. If a bundle </t>
is replayed outside <t>
of its lifetime, then the replay attack will fail as the bundle will NOTE: Irrespective of whether BPSec is used, traffic
be discarded. Similarly, additional blocks such as the Bundle Age may be signed analysis will be possible.
and validated to identify replay attacks. Finally, security context parameters </t>
within BIB and BCB blocks may include anti-replay mechanisms such as </section>
session identifiers, nonces, and dynamic passwords as supported by network char <section toc="default" numbered="true">
acteristics. <name>Modification Attacks</name>
</t> <t>
As a node participating in the delay-tolerant network between Alice
and Bob,
Olive will also be able to modify the received bundle,
including non-BPSec data such as the primary block,
payload blocks, or block processing control flags as
defined in <xref target="RFC9171" format="default"/>.
Olive will be able to undertake activities including
modification of data within the blocks, replacement of
blocks, addition of blocks, or removal of blocks. Within
BPSec, both the BIB and BCB provide integrity-protection
mechanisms to detect or prevent data manipulation attempts
by Olive.
</t>
<t>
The BIB provides that protection to another block that is
its security target. The cryptographic mechanisms used to
generate the BIB should be strong against collision
attacks, and Olive should not have access to the
cryptographic material used by the originating node to
generate the BIB (e.g., K<sub>A</sub>). If both of these conditions
are true, Olive will be unable to modify the security
target or the BIB, and thus she cannot lead Bob to validate the secu
rity
target as originating from Alice.
</t>
<t>
Since BPSec security operations are implemented by placing
blocks in a bundle, there is no in-band mechanism for
detecting or correcting certain cases where Olive removes
blocks from a bundle. If Olive removes a BCB, but keeps
the security target, the security target remains encrypted
and there is a possibility that there may no longer be
sufficient information to decrypt the block at its
destination. If Olive removes both a BCB (or BIB) and its
security target, there is no evidence left in the bundle of
the security operation. Similarly, if Olive removes the
BIB, but not the security target, there is no evidence left
in the bundle of the security operation. In each of these
cases, the implementation of BPSec must be combined with
policy configuration at endpoints in the network that
describe the expected and required security operations
that must be applied on transmission and that are expected to
be present on receipt. This or other similar out-of-band
information is required to correct for removal of security
information in the bundle.
</t>
<t>
A limitation of the BIB may exist within the
implementation of BIB validation at the destination node.
If Olive is a legitimate node within the delay-tolerant network, the
BIB
generated by Alice with K<sub>A</sub> can be replaced with a new BIB
generated with K<sub>M</sub> and forwarded to Bob. If Bob is only
validating that the BIB was generated by a legitimate
user, Bob will acknowledge the message as originating from
Olive instead of Alice. Validating a BIB indicates only
that the BIB was generated by a holder of the relevant
key; it does not provide any guarantee that the bundle or
block was created by the same entity. In order to provide
verifiable integrity checks, the BCB should require an
encryption scheme that is Indistinguishable under adaptive
Chosen Ciphertext Attack (IND-CCA2) secure. Such an
encryption scheme will guard against signature
substitution attempts by Olive. In this case, Alice
creates a BIB with the protected data block as the
security target and then creates a BCB with both the BIB
and protected data block as its security targets.
</t>
</section>
<section anchor="SecConsTopAtck" toc="default" numbered="true">
<name>Topology Attacks</name>
<t>
If Olive is in an OPA position within the delay-tolerant network, s
he is able
to influence how any bundles that come to her may pass
through the network. Upon receiving and processing a
bundle that must be routed elsewhere in the network,
Olive has three options as to how to proceed: not forward
the bundle, forward the bundle as intended, or forward
the bundle to one or more specific nodes within the
network.
</t>
<t>
Attacks that involve rerouting the bundles throughout the
network are essentially a special case of the modification
attacks described in this section, one where the attacker is
modifying fields within the primary block of the bundle.
Given that BPSec cannot encrypt the contents of the
primary block, alternate methods must be used to prevent
this situation. These methods may include requiring BIBs
for primary blocks, using encapsulation, or otherwise
strategically manipulating primary block data. The
details of any such mitigation technique are specific to
the implementation of the deploying network and are outside of
the scope of this document.
</t>
<t>
Furthermore, routing rules and policies may be useful in
enforcing particular traffic flows to prevent topology
attacks. While these rules and policies may utilize some
features provided by BPSec, their definition is beyond the
scope of this specification.
</t>
</section>
<section toc="default" numbered="true">
<name>Message Injection</name>
<t>
Olive is also able to generate new bundles and transmit
them into the delay-tolerant network at will.
These bundles may be either 1)
copies or slight modifications of previously observed
bundles (i.e., a replay attack) or 2) entirely new bundles
generated based on the Bundle Protocol, BPSec, or other
bundle-related protocols. With these attacks, Olive's
objectives may vary, but may be targeting either the
Bundle Protocol or application-layer protocols conveyed by
the Bundle Protocol. The target could also be the storage
and computing capabilities of the nodes running the bundle or
application-layer protocols (e.g., a denial of service to
flood on the storage of the store-and-forward mechanism or
a computation that would process the bundles and perhaps
prevent other activities).
</t>
<t>
BPSec relies on cipher suite capabilities to prevent
replay or forged message attacks. A BCB used with
appropriate cryptographic mechanisms may provide replay
protection under certain circumstances. Alternatively,
application data itself may be augmented to include
mechanisms to assert data uniqueness and then be protected
with a BIB, a BCB, or both along with other block data. In
such a case, the receiving node would be able to validate
the uniqueness of the data.
</t>
<t>
For example, a BIB may be used to validate the integrity
of a bundle's primary block, which includes a timestamp
and lifetime for the bundle. If a bundle is replayed
outside of its lifetime, then the replay attack will fail
as the bundle will be discarded. Similarly, additional
blocks, such as the Bundle Age, may be signed and validated
to identify replay attacks. Finally, security context
parameters within BIBs and BCBs may include
anti-replay mechanisms such as session identifiers,
nonces, and dynamic passwords as supported by network
characteristics.
</t>
</section>
</section> </section>
</section> </section>
</section> <section anchor="sec_ctx" numbered="true" toc="default">
<name>Security Context Considerations</name>
<section anchor="sec_ctx" title="Security Context Considerations"> <section numbered="true" toc="default">
<section title="Mandating Security Contexts"> <name>Mandating Security Contexts</name>
<t> <t>
Because of the diversity of networking scenarios and node capabilities Because of the diversity of networking scenarios and node
that may utilize BPSec there is a risk that a single security context m capabilities that may utilize BPSec, there is a risk that a
andated single security context mandated for every possible BPSec
for every possible BPSec implementation is not feasible. For example, a implementation is not feasible. For example, a security
security context context appropriate for a resource-constrained node with
appropriate for a resource-constrained node with limited limited connectivity may be inappropriate for use in a
connectivity may be inappropriate for use in a well-resourced, well well-resourced, well-connected node.
connected node. </t>
</t> <t>
<t> This does not mean that the use of BPSec in a particular
This does not mean that the use of BPSec in a particular network is network is meant to happen without security contexts for
meant to be used without security contexts for interoperability and interoperability and default behavior. Network designers must
default behavior. Network designers must identify the minimal set of identify the minimal set of security contexts necessary for
security contexts necessary for functions in their network. For example functions in their network. For example, a default set of
, security contexts could be created for use over the
a default set of security contexts could be created for use over the terrestrial Internet, and they could be required by any BPSec implement
terrestrial Internet and required by any BPSec implementation communica ation
ting communicating over the terrestrial Internet.
over the terrestrial Internet. </t>
</t> <t>
<t> To ensure interoperability among various implementations, all
To ensure interoperability among various implementations, all BPSec imp BPSec implementations <bcp14>MUST</bcp14> support at least
lementations the current, mandatory security context(s) defined in IETF Standards Tr
MUST support at least the current IETF standards-track mandatory securi ack
ty context(s). RFCs. As of this writing, that BP mandatory security
As of this writing, that BCP mandatory security context is specified in context is specified in <xref target="RFC9173"
<xref target="I-D.ietf-dtn-bpsec-default-sc"/>, format="default"/>, but the mandatory security context(s)
but the mandatory security context(s) might change over time in accorda might change over time in accordance with usual IETF
nce with usual IETF processes. processes. Such changes are likely to occur in the future
Such changes are likely to occur in the future if/when flaws are discov if/when flaws are discovered in the applicable cryptographic
ered in the applicable cryptographic
algorithms, for example. algorithms, for example.
</t> </t>
<t>
<t> Additionally, BPSec implementations need to support the
Additionally, BPsec implementations need to support the security contex security contexts that are required by the BP
ts which are specified and/or used networks in which they are deployed.
by the BP networks in which they are deployed. </t>
</t> <t>
<t> If a node serves as a gateway between two or more networks,
If a node serves as a gateway amongst two or more networks, the BPSec i the BPSec implementation at that node needs to support the
mplementation at that node needs union of security contexts mandated in those networks.
to support the union of security contexts mandated in those networks. </t>
</t> <t>
<t> BPSec has been designed to allow for a diversity of security
BPSec has been designed to allow for a diversity of security contexts contexts and for new contexts to be defined over time. The
and for new contexts to be defined over time. The use of different secu use of different security contexts does not change the BPSec
rity contexts protocol itself, and the definition of new security contexts
does not change the BPSec protocol itself and the definition of new sec <bcp14>MUST</bcp14> adhere to the requirements of such
urity contexts contexts as presented in this section and generally in this
MUST adhere to the requirements of such contexts as presented in this s specification.
ection and </t>
generally in this specification. <t>
</t> Implementers should monitor the state of security context
<t> specifications to check for future updates and replacement.
Implementors should monitor the state of security context specification </t>
s to check </section>
for future updates and replacement. <section numbered="true" toc="default">
</t> <name>Identification and Configuration</name>
</section> <t>
Security blocks uniquely identify the security context to be
<section title="Identification and Configuration"> used in the processing of their security services. The
<t> security context for a security block <bcp14>MUST</bcp14> be
Security blocks uniquely identify the security context to be used in th uniquely identifiable and <bcp14>MAY</bcp14> use parameters
e for customization.
processing of their security services. The security context for a secur </t>
ity <t>
block MUST be uniquely identifiable and MAY use parameters for customiz To reduce the number of security contexts used in a network,
ation. security context designers should make security contexts
</t> customizable through the definition of security context
parameters. For example, a single security context could be
<t> associated with a single cipher suite and security context
To reduce the number of security contexts used in a network, security c parameters could be used to configure the use of this
ontext security context with different key lengths and different key
designers should make security contexts customizable through the defini management options without needing to define separate
tion of
security context parameters. For example, a single security context cou
ld be
associated with a single cipher suite and security context parameters c
ould be
used to configure the use of this security context with different key l
engths
and different key management options without needing to define separate
security contexts for each possible option. security contexts for each possible option.
</t> </t>
<t>
<t> A single security context may be used in the application of
A single security context may be used in the application of more than o more than one security service. This means that a security
ne context identifier <bcp14>MAY</bcp14> be used with a BIB,
security service. This means that a security context identifier MAY be with a BCB, or with any other BPSec-compliant security block.
used with a BIB, with a BCB, or with any other BPSec-compliant security The definition of a security context <bcp14>MUST</bcp14>
block. identify which security services may be used with the
The definition of a security context MUST identify which security servi security context, how security context parameters are
ces may interpreted as a function of the security operation being
be used with the security context, how security context parameters are supported, and which security results are produced for each
interpreted security service.
as a function of the security operation being supported, and which secu </t>
rity <t>
results are produced for each security service. Network operators must determine the number, type, and
</t> configuration of security contexts in a system. Networks with
rapidly changing configurations may define relatively few
<t> security contexts with each context customized with multiple
Network operators must determine the number, type, and configuration parameters. For networks with more stability, or an increased
of security contexts in a system. Networks with rapidly changing need for confidentiality, a larger number of contexts can be
configurations may define relatively few security contexts with each defined with each context supporting few, if any, parameters.
context customized with multiple parameters. For networks with more </t>
stability, or an increased need for confidentiality, a larger number
of contexts can be defined with each context supporting few, if any,
parameters.
</t>
<texttable align="center" anchor="sec_ctx_ex">
<preamble>
Security Context Examples
</preamble>
<ttcol align="center">Context Type</ttcol>
<ttcol align="center">Parameters</ttcol>
<ttcol align="center">Definition</ttcol>
<c>Key Exchange AES</c>
<c>Encrypted Key, IV</c>
<c>AES-GCM-256 cipher suite with provided ephemeral key encrypted with
a predetermined key encryption key and clear text initialization vector.</c>
<c>Pre-shared Key AES</c>
<c>IV</c>
<c>AES-GCM-256 cipher suite with predetermined key and predetermined
key rotation policy.</c>
<c>Out of Band AES</c>
<c>None</c>
<c>AES-GCM-256 cipher suite with all info predetermined.</c>
</texttable>
</section>
<section title="Authorship"> <table align="center" anchor="sec_ctx_ex">
<t> <name>Security Context Examples</name>
<thead>
<tr>
<th align="center">Context Type</th>
<th align="center">Parameters</th>
<th align="center">Definition</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">Key Exchange AES</td>
<td align="center">Encrypted Key, IV</td>
<td align="center">AES-GCM-256 cipher suite with
provided ephemeral key encrypted with a predetermined
key encryption key and cleartext initialization
vector.</td>
</tr>
<tr>
<td align="center">Pre-Shared Key AES</td>
<td align="center">IV</td>
<td align="center">AES-GCM-256 cipher suite with
predetermined key and predetermined key-rotation
policy.</td>
</tr>
<tr>
<td align="center">Out-of-Band AES</td>
<td align="center">None</td>
<td align="center">AES-GCM-256 cipher suite with all
info predetermined.</td>
</tr>
</tbody>
</table>
</section>
<section numbered="true" toc="default">
<name>Authorship</name>
<t>
Developers or implementers should consider the diverse Developers or implementers should consider the diverse
performance and conditions of networks on which the Bundle Protocol performance and conditions of networks on which the Bundle
(and therefore BPSec) will operate. Specifically, the delay and Protocol (and, therefore, BPSec) will operate. Specifically,
capacity of delay-tolerant networks can vary substantially. Developers the delay and capacity of DTNs can vary
should consider these conditions to better describe substantially. Developers should consider these conditions to
the conditions when those contexts will operate or exhibit better describe the conditions in which those contexts will
vulnerability, and selection of these contexts for implementation operate or exhibit vulnerability, and selection of these
should be made with consideration for this reality. There are key contexts for implementation should be made with consideration
differences that may limit the opportunity for a security context to le for this reality. There are key differences that may limit
verage existing the opportunity for a security context to leverage existing
cipher suites and technologies that have been developed for use in cipher suites and technologies that have been developed for
traditional, more reliable networks: use in more reliable networks:
<list style="symbols"> </t>
<t> <dl spacing="normal">
Data Lifetime: Depending on the application environment, <dt>Data Lifetime:</dt><dd>Depending on the application environment,
bundles may persist on the network for extended periods of bundles may persist on the network for extended periods of
time, perhaps even years. Cryptographic algorithms should be time, perhaps even years. Cryptographic algorithms should be
selected to ensure protection of data against attacks for a selected to ensure protection of data against attacks for a
length of time reasonable for the application. length of time reasonable for the application.
</t> </dd>
<dt>One-Way Traffic:</dt><dd>Depending on the application
<t> environment, it is possible that only a one-way connection
One-Way Traffic: Depending on the application environment, it may exist between two endpoints, or if a two-way connection
is possible that only a one-way connection may exist between does exist, the round-trip time may be extremely large. This
two endpoints, or if a two-way connection does exist, the round- may limit the utility of session key generation mechanisms,
trip time may be extremely large. This may limit the utility such as Diffie-Hellman, as a two-way handshake may not be
of session key generation mechanisms, such as Diffie-Hellman, feasible or reliable.
as a two-way handshake may not be feasible or reliable. </dd>
</t> <dt>Opportunistic Access:</dt><dd>Depending on the application environ
ment,
<t>
Opportunistic Access: Depending on the application environment,
a given endpoint may not be guaranteed to be accessible within a given endpoint may not be guaranteed to be accessible within
a certain amount of time. This may make asymmetric a certain amount of time. This may make asymmetric
cryptographic architectures which rely on a key distribution cryptographic architectures that rely on a key distribution
center or other trust center impractical under certain center or other trust center impractical under certain
conditions. conditions.
</t> </dd>
</list> </dl>
</t> <t>
<t>
When developing security contexts for use with BPSec, the following When developing security contexts for use with BPSec, the following
information SHOULD be considered for inclusion in these specifications. information <bcp14>SHOULD</bcp14> be considered for inclusion in these sp ecifications.
<list style="symbols"> </t>
<t> <dl spacing="normal">
Security Context Parameters. Security contexts MUST define <dt>Security Context Parameters:</dt><dd>Security contexts
their parameter Ids, the data types of those parameters, and <bcp14>MUST</bcp14> define their parameter Ids, the data
their CBOR encoding. types of those parameters, and their CBOR encoding.
</t> </dd>
<t> <dt>Security Results:</dt><dd>Security contexts
Security Results. Security contexts MUST define their security <bcp14>MUST</bcp14> define their security result Ids, the
result Ids, the data types of those results, and their CBOR data types of those results, and their CBOR encoding.
encoding. </dd>
</t> <dt>New Canonicalizations:</dt><dd>Security contexts may
<t> define new canonicalization algorithms as necessary.</dd>
New Canonicalizations. Security contexts may define new
canonicalization algorithms as necessary. <dt>Ciphertext Size:</dt><dd><t>Security contexts
<bcp14>MUST</bcp14> state whether their associated cipher
suites generate ciphertext (to include any authentication
information) that is of a different size than the input
plaintext.
</t> </t>
<t> <t>
Cipher-Text Size. Security contexts MUST state whether their
associated cipher suites generate cipher text (to include any
authentication information) that is of a different size than
the input plain text.
<vspace blankLines="1"/>
If a security context does not wish to alter the size of the If a security context does not wish to alter the size of the
plain text it should place overflow bytes and authentication tags plaintext, it should place overflow bytes and authentication tags
in security result fields. in security result fields.
</t> </t>
<t> </dd>
Block Header Information. Security contexts SHOULD include block <dt>Block Header Information:</dt><dd>Security contexts
header information that is considered to be immutable for the <bcp14>SHOULD</bcp14> include block header information that
block. This information MAY include the block type code, block nu is considered to be immutable for the block. This
mber, information <bcp14>MAY</bcp14> include the block type code,
CRC Type and CRC field (if present or if missing and unlikely to block number, CRC type, and CRC field (if present or if
be missing and unlikely to be added later), and possibly
added later), and possibly certain block processing control flags certain block processing control flags. Designers should
. input these fields as additional data for integrity
Designers should input these fields as additional data for integr protection when these fields are expected to remain
ity unchanged over the path the block will take from the
protection when these fields are expected to remain unchanged ove security source to the security acceptor. Security contexts
r the considering block header information <bcp14>MUST</bcp14>
path the block will take from the security source to the security describe expected behavior when these fields fail their
acceptor. integrity verification.
Security contexts considering block header information MUST descr </dd>
ibe <dt>Handling CRC Fields:</dt><dd>Security contexts may
expected behavior when these fields fail their integrity verifica include algorithms that alter the contexts of their security
tion. target block, such as the case when encrypting the
</t> block-type-specific data of a target block as part of a BCB
<t> confidentiality service. Security context specifications
Handling CRC Fields. Security contexts may include algorithms tha <bcp14>SHOULD</bcp14> address how preexisting CRC type and
t alter the CRC value fields be handled. For example, a BCB security
contexts of their security target block, such as the case when context could remove the plaintext CRC value from its
encrypting the block-type-specific data of a target block as part target upon encryption and replace or recalculate the value
oF upon decryption.
a BCB confidentiality service. Security context specifications SH </dd>
OULD </dl>
address how preexisting CRC-Type and CRC-Value fields be handled. </section>
For </section>
example, a BCB security context could remove the plain-text CRC v <section anchor="Extensions" toc="default" numbered="true">
alue from <name>Defining Other Security Blocks</name>
its target upon encryption and replace or recalculate the value u <t>
pon decryption. Other Security Blocks (OSBs) may be defined and used in addition to the
</t> security blocks identified in this specification.
</list> BIB, BCB, and any future OSBs can coexist within a bundle and can be
</t> considered in conformance with BPSec if all of the following requirements
</section>
</section>
<section anchor="Extensions" title="Defining Other Security Blocks" toc="default
">
<t>
Other security blocks (OSBs) may be defined and used in addition to the
security blocks identified in this specification. Both the usage of
BIB, BCB, and any future OSBs can co-exist within a bundle and can be
considered in conformance with BPSec if each of the following requirements
are met by any future identified security blocks. are met by any future identified security blocks.
</t>
<list style="symbols"> <ul spacing="normal">
<t> <li>
Other security blocks (OSBs) MUST NOT reuse any enumerations OSBs <bcp14>MUST NOT</bcp14> reuse any enumerations
identified in this specification, to include the block type codes identified in this specification, to include the block type codes
for BIB and BCB. for BIB and BCB.
</t> </li>
<t> <li>
An OSB definition MUST state whether it can be the target of a BIB An OSB definition <bcp14>MUST</bcp14> state whether it can
or a BCB. The definition MUST also state whether the OSB can target be the target of a BIB or a BCB. The definition
<bcp14>MUST</bcp14> also state whether the OSB can target
a BIB or a BCB. a BIB or a BCB.
</t> </li>
<t> <li>
An OSB definition MUST provide a deterministic processing order in An OSB definition <bcp14>MUST</bcp14> provide a
the event that a bundle is received containing BIBs, BCBs, and OSBs. deterministic processing order in the event that a bundle
This processing order MUST NOT alter the BIB and BCB processing is received containing BIBs, BCBs, and OSBs. This
orders identified in this specification. processing order <bcp14>MUST NOT</bcp14> alter the BIB and
</t> BCB processing orders identified in this specification.
</li>
<t> <li>
An OSB definition MUST provide a canonicalization algorithm if the An OSB definition <bcp14>MUST</bcp14> provide a
default non-primary-block canonicalization algorithm cannot be used canonicalization algorithm if the default algorithm for
to generate a deterministic input for a cipher suite. This non-primary-block canonicalization cannot be
requirement can be waived if the OSB is defined so as to never be used to generate a deterministic input for a cipher
the security target of a BIB or a BCB. suite. This requirement can be waived if the OSB is
</t> defined so as to never be the security target of a BIB or
a BCB.
<t> </li>
An OSB definition MUST NOT require any behavior of a BPSEC-BPA that <li>
is in conflict with the behavior identified in this specification. An OSB definition <bcp14>MUST NOT</bcp14> require any
In particular, the security processing requirements imposed by this behavior of a BPSec BPA that is in conflict with the
specification must be consistent across all BPSEC-BPAs in a network. behavior identified in this specification. In particular,
</t> the security processing requirements imposed by this
specification must be consistent across all BPSec BPAs in
<t> a network.
The behavior of an OSB when dealing with fragmentation must be speci </li>
fied <li>
and MUST NOT lead to ambiguous processing states. In particular, an The behavior of an OSB when dealing with fragmentation
OSB definition should address how to receive and process an OSB in a must be specified and <bcp14>MUST NOT</bcp14> lead to
bundle fragment that may or may not also contain its security target ambiguous processing states. In particular, an OSB
. definition should address how to receive and process an
An OSB definition should also address whether an OSB may be added to OSB in a bundle fragment that may or may not also contain
a its security target. An OSB definition should also
bundle marked as a fragment. address whether an OSB may be added to a bundle marked as
</t> a fragment.
</list> </li>
</t> </ul>
<t>
Additionally, policy considerations for the management, monitoring, and
configuration associated with blocks SHOULD be included in any OSB definit
ion.
</t>
<t>
NOTE: The burden of showing compliance with processing rules is placed upo
n
the specifications defining new security blocks and the identification of
such blocks
shall not, alone, require maintenance of this specification.
</t>
</section>
<section anchor="IANA" title="IANA Considerations" toc="default">
<t>
This specification includes fields requiring registries managed by
IANA.
</t>
<section anchor="BlockType" title="Bundle Block Types" toc="default">
<t> <t>
This specification allocates two block types from the existing Additionally, policy considerations for the management,
"Bundle Block Types" registry defined in <xref target="RFC6255"/>. monitoring, and configuration associated with blocks
<bcp14>SHOULD</bcp14> be included in any OSB definition.
</t> </t>
<texttable align="center" anchor="iana_table">
<preamble>
Additional Entries for the Bundle Block-Type Codes Registry:
</preamble>
<ttcol align="center">Value</ttcol>
<ttcol align="center">Description</ttcol>
<ttcol align="center">Reference</ttcol>
<c>TBA</c>
<c>Block Integrity Block</c>
<c>This document</c>
<c>TBA</c>
<c>Block Confidentiality Block</c>
<c>This document</c>
</texttable>
<t> <t>
The Bundle Block Types namespace notes whether a block type is NOTE: The burden of showing compliance with processing rules is
meant for use in BP version 6, BP version 7, or both. The two block ty placed upon the specifications defining new security blocks, and
pes the identification of such blocks shall not, alone, require
defined in this specification are meant for use with BP version 7. maintenance of this specification.
</t> </t>
</section>
</section> <section anchor="IANA" toc="default" numbered="true">
<name>IANA Considerations</name>
<section anchor="secreasoncode" title="Bundle Status Report Reason Codes">
<t> <t>
This specification allocates five reason codes from the existing This specification includes fields that require registries managed by
"Bundle Status Report Reason Codes" registry defined in <xref target="R IANA.
FC6255"/>.
</t> </t>
<section anchor="BlockType" toc="default" numbered="true">
<name>Bundle Block Types</name>
<t>
This specification allocates two block types from the
existing "Bundle Block Types" registry defined in <xref
target="RFC6255" format="default"/>.
</t>
<texttable align="center"> <table align="center" anchor="iana_table">
<preamble> <name> Additional Entries for the "Bundle Block Types" Registry</name>
Additional Entries for the Bundle Status Report Reason Codes Registr <thead>
y: <tr>
</preamble> <th align="center">Value</th>
<th align="center">Description</th>
<ttcol align="center">BP Version</ttcol> <th align="center">Reference</th>
<ttcol align="center">Value</ttcol> </tr>
<ttcol align="center">Description</ttcol> </thead>
<ttcol align="center">Reference</ttcol> <tbody>
<tr>
<c>7</c> <td align="center">11</td>
<c>TBD</c> <td align="center">Block Integrity</td>
<c>Missing Security Operation</c> <td align="center">This document</td>
<c>This document, Section <xref target="ReasonCodes"/> </c> </tr>
<tr>
<c>7</c> <td align="center">12</td>
<c>TBD</c> <td align="center">Block Confidentiality</td>
<c>Unknown Security Operation</c> <td align="center">This document</td>
<c>This document, Section <xref target="ReasonCodes"/></c> </tr>
</tbody>
<c>7</c> </table>
<c>TBD</c> <t>
<c>Unexpected Security Operation</c> The "Bundle Block Types" registry notes whether a block type is
<c>This document, Section <xref target="ReasonCodes"/></c> meant for use in BP version 6, BP version 7 (BPv7), or both. The two b
lock types
<c>7</c> defined in this specification are meant for use with BPv7.
<c>TBD</c> </t>
<c>Failed Security Operation</c> </section>
<c>This document, Section <xref target="ReasonCodes"/></c> <section anchor="secreasoncode" numbered="true" toc="default">
<name>Bundle Status Report Reason Codes</name>
<c>7</c> <t>
<c>TBD</c> This specification allocates five reason codes from the
<c>Conflicting Security Operation</c> existing "Bundle Status Report Reason Codes" registry defined
<c>This document, Section <xref target="ReasonCodes"/></c> in <xref target="RFC6255" format="default"/>.
</t>
</texttable> <table align="center">
</section> <name> Additional Entries for the "Bundle Status Report Reason Codes" R
egistry</name>
<section anchor="SecCtx" title="Security Context Identifiers"> <thead>
<tr>
<t> <th align="center">BP Version</th>
<th align="center">Value</th>
<th align="center">Description</th>
<th align="center">Reference</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">7</td>
<td align="center">12</td>
<td align="center">Missing security operation</td>
<td align="center">This document, <xref target="ReasonCodes" forma
t="default"/> </td>
</tr>
<tr>
<td align="center">7</td>
<td align="center">13</td>
<td align="center">Unknown security operation</td>
<td align="center">This document, <xref target="ReasonCodes" forma
t="default"/></td>
</tr>
<tr>
<td align="center">7</td>
<td align="center">14</td>
<td align="center">Unexpected security operation</td>
<td align="center">This document, <xref target="ReasonCodes" forma
t="default"/></td>
</tr>
<tr>
<td align="center">7</td>
<td align="center">15</td>
<td align="center">Failed security operation</td>
<td align="center">This document, <xref target="ReasonCodes" forma
t="default"/></td>
</tr>
<tr>
<td align="center">7</td>
<td align="center">16</td>
<td align="center">Conflicting security operation</td>
<td align="center">This document, <xref target="ReasonCodes" forma
t="default"/></td>
</tr>
</tbody>
</table>
</section>
<section anchor="SecCtx" numbered="true" toc="default">
<name>Security Context Identifiers</name>
<t>
BPSec has a Security Context Identifier field for which BPSec has a Security Context Identifier field for which
IANA is requested to create and maintain a new registry IANA has created a new registry
named "BPSec Security Context Identifiers". Initial values named "BPSec Security Context Identifiers". Initial values
for this registry are given below. for this registry are given below.
</t> </t>
<t>
<t> The registration policy for this registry is Specification
The registration policy for this registry is: Specification Required (see <xref target="RFC8126" format="default"/>).
Required. </t>
</t> <t>
The value range: signed 16-bit integer.
<t> </t>
The value range is: signed 16-bit integer. <table align="center" anchor="sec_ctx_table">
</t> <name>"BPSec Security Context Identifier" Registry</name>
<thead>
<texttable align="center" anchor="sec_ctx_table"> <tr>
<preamble> <th align="center">Value</th>
BPSec Security Context Identifier Registry <th align="center">Description</th>
</preamble> <th align="center">Reference</th>
</tr>
<ttcol align="center">Value</ttcol> </thead>
<ttcol align="center">Description</ttcol> <tbody>
<ttcol align="center">Reference</ttcol> <tr>
<td align="center">&lt; 0 </td>
<c>&lt; 0 </c> <td align="center">Reserved</td>
<c>Reserved</c> <td align="center">This document</td>
<c>This document</c> </tr>
<tr>
<c>0</c> <td align="center">0</td>
<c>Reserved</c> <td align="center">Reserved</td>
<c>This document</c> <td align="center">This document</td>
</texttable> </tr>
</tbody>
<t> </table>
<t>
Negative security context identifiers are reserved for local/site-speci fic uses. Negative security context identifiers are reserved for local/site-speci fic uses.
The use of 0 as a security context identifier is for non-operational te The use of 0 as a security context identifier is for nonoperational tes
sting purposes only. ting purposes only.
</t> </t>
</section> </section>
</section>
</section> </middle>
<back>
</middle>
<back>
<references title="Normative References">
&RFC3552;
&RFC8174;
&RFC2119;
&RFC8949;
&RFC6255;
<?rfc include="reference.I-D.draft-ietf-dtn-bpbis-31"?>
<reference anchor="I-D.ietf-dtn-bpsec-default-sc">
<front>
<title> BPSec Default Security Contexts </title>
<author initials="E." surname="Birrane">
</author>
<date month="February" year="2021"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-dtn-bpsec-default-sc-0
1"/>
</reference>
</references>
<references title="Informative References">
&RFC4838; <references>
&RFC6257; <name>References</name>
<references>
<name>Normative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3552.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8949.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.6255.xml"/>
<?rfc include="reference.I-D.draft-birrane-dtn-sbsp-01"?> <reference anchor='RFC9171' target='https://www.rfc-editor.org/info/rfc9171'>
<front>
<title>Bundle Protocol Version 7</title>
<author initials='S' surname='Burleigh' fullname='Scott Burleigh'>
<organization />
</author>
<author initials='K' surname='Fall' fullname='Kevin Fall'>
<organization />
</author>
<author initials='E' surname='Birrane, III' fullname='Edward J. Birrane, III'>
<organization />
</author>
<date month='January' year='2022' />
</front>
<seriesInfo name="RFC" value="9171"/>
<seriesInfo name="DOI" value="10.17487/RFC9171"/>
</reference>
</references> <reference anchor='RFC9173' target='https://www.rfc-editor.org/info/rfc9173'>
<front>
<title>Default Security Contexts for Bundle Protocol Security (BPSec)</title>
<author initials='E' surname='Birrane, III' fullname='Edward J. Birrane, III'>
<organization />
</author>
<author fullname="Alex White" initials="A." surname="White">
<organization />
</author>
<author fullname="Sarah Heiner" initials="S." surname="Heiner">
<organization />
</author>
<date month='January' year='2022' />
</front>
<seriesInfo name="RFC" value="9173"/>
<seriesInfo name="DOI" value="10.17487/RFC9173"/>
</reference>
<section anchor="contr" title="Acknowledgements" toc="default"> </references>
<t>The following participants contributed technical material, use cases, <references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.4838.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.6257.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8126.xml"/>
</references>
</references>
<section anchor="contr" toc="default" numbered="false">
<name>Acknowledgments</name>
<t>The following participants contributed technical material, use cases,
and useful thoughts on the overall approach to this security and useful thoughts on the overall approach to this security
specification: Scott Burleigh of the Jet Propulsion Laboratory, specification: <contact fullname="Scott Burleigh"/> of the IPNGROUP, <con
Angela Hennessy of the Laboratory for Telecommunications tact fullname="Angela Hennessy"/> of the Laboratory for Telecommunications
Sciences, and Amy Alford, Angela Dalton, and Cherita Corbett of the Johns Sciences, <contact fullname="Amy Alford"/> and <contact fullname="Cherita
Hopkins Corbett"/> of the Johns Hopkins
University Applied Physics Laboratory.</t> University Applied Physics Laboratory (JHU/APL), and <contact fullname="An
</section> gela Dalton"/> of AMD Research.</t>
</back> <t>Additionally, Benjamin Kaduk of Akamai Technologies provided a detailed
technical review that resulted in a stronger and more precise specification. <
/t>
</section>
</back>
</rfc> </rfc>
 End of changes. 238 change blocks. 
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