wdiff rfc8225.original rfc8225.txt

STIR
Internet Engineering Task Force (IETF) C. Wendt
Internet-Draft
Request for Comments: 8225 Comcast
Intended status:
Category: Standards Track J. Peterson
Expires: August 13, 2017
ISSN: 2070-1721 Neustar Inc.
February 09, 2017 2018

PASSporT: Personal Assertion Token (PASSporT)
draft-ietf-stir-passport-11

Abstract

This document defines a method for creating and validating a token
that cryptographically verifies an originating identity, or identity or, more
generally
generally, a URI or telephone number representing the originator of
personal communications. The PASSporT token Personal Assertion Token, PASSporT, is
cryptographically signed to protect the integrity of the identity of
the originator and to verify the assertion of the identity
information at the destination. The cryptographic signature is
defined with the intention that it can confidently verify the
originating persona even when the signature is sent to the
destination party over an insecure channel. PASSporT is particularly
useful for many personal communications personal-communications applications over IP networks
and other multi-hop interconnection scenarios where the originating
and destination parties may not have a direct trusted relationship.

Status of This Memo

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provisions of BCP 78 and BCP 79.

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(IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid the IETF community. It has
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This Internet-Draft will expire on August 13, 2017.
https://www.rfc-editor.org/info/rfc8225.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 ....................................................4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 .....................................................4
3. PASSporT Token Overview . . . . . . . . . . . . . . . . . . . 4 ...............................................5
4. PASSporT Header . . . . . . . . . . . . . . . . . . . . . . . 5 .................................................6
4.1. "typ" (Type) Header Parameter . . . . . . . . . . . . . . 5 ..............................6
4.2. "alg" (Algorithm) Header Parameter . . . . . . . . . . . 5 .........................6
4.3. "x5u" (X.509 URL) Header Parameter . . . . . . . . . . . 5 .........................6
4.4. Example PASSporT header . . . . . . . . . . . . . . . . . 6 Header ....................................7
5. PASSporT Payload . . . . . . . . . . . . . . . . . . . . . . 6 ................................................7
5.1. JWT defined claims . . . . . . . . . . . . . . . . . . . 6 JWT-Defined Claims .........................................7
5.1.1. "iat" - Issued At claim . . . . . . . . . . . . . . . 6 (Issued At) Claim .............................7
5.2. PASSporT specific claims . . . . . . . . . . . . . . . . 6 PASSporT-Specific Claims ...................................8
5.2.1. Originating and Destination Identity Claims . . . . . 7 .........8
5.2.2. "mky" - Media Key claim . . . . . . . . . . . . . . . 8 (Media Key) Claim ............................10
6. PASSporT Signature . . . . . . . . . . . . . . . . . . . . . 10 .............................................11
7. Compact form Form of PASSporT . . . . . . . . . . . . . . . . . . 10 .......................................12
7.1. Example Compact form Form of PASSporT Token . . . . . . . . . . . 11 ..........................13
8. Extending PASSporT . . . . . . . . . . . . . . . . . . . . . 11 .............................................13
8.1. "ppt" (PASSporT) header parameter . . . . . . . . . . . . 12 Header Parameter .........................13
8.2. Example extended Extended PASSporT header . . . . . . . . . . . . 12 Header ..........................14
8.3. Extended PASSporT Claims . . . . . . . . . . . . . . . . 13 ..................................14
9. Deterministic JSON Serialization . . . . . . . . . . . . . . 13 ...............................15
9.1. Example PASSport deterministic PASSporT Deterministic JSON form . . . . . . . . 14 Form ..................16
10. Security Considerations . . . . . . . . . . . . . . . . . . . 15 .......................................17
10.1. Avoidance of replay Replay and cut and paste attacks . . . . . 15 Cut-and-Paste Attacks ............17
10.2. Solution Considerations . . . . . . . . . . . . . . . . 15 ..................................18
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 ...........................................18
11.1. Media Type Registration . . . . . . . . . . . . . . . . 16
11.1.1. Media Type Registry Contents Additions Requested . . 16 ..................................18
11.2. JSON Registrations in "JSON Web Token Claims Registration . . . . . . . . . . . 17
11.2.1. Registry Contents Additions Requested . . . . . . . 17 Claims" .................19
11.3. JSON Web Signature and Encryption Header Parameter
Registry . . . . . . . . . . . . . . . . . . . . . . . . 18
11.3.1. Registry Contents Additions Requested . . . . . . . 18
11.4. PASSporT Extension Registry Request . . . . . . . . . . 18
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
13.1. Registration in "JSON Web Signature and
Encryption Header Parameters" ............................20
11.4. PASSporT Extensions Registry .............................20
12. References ....................................................20
12.1. Normative References . . . . . . . . . . . . . . . . . . 18
13.2. .....................................20
12.2. Informative References . . . . . . . . . . . . . . . . . 20 ...................................22
Appendix A. Example ES256 based ES256-Based PASSporT JWS Serialization and
Signature . . . . . . . . . . . . . . . . . . . . . 20 .............................................23
A.1. X.509 Private Key in PKCS#8 format PKCS #8 Format for ES256 Example** . 22 Example ......24
A.2. X.509 Public Key for ES256 Example** . . . . . . . . . . 22 Example .........................25
Acknowledgments ...................................................25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 ................................................25

1. Introduction

In today's IP-enabled telecommunications world, there is a growing
concern about the ability to trust incoming invitations for
communications sessions, including video, voice voice, and messaging
[RFC7340]. As an example, modern telephone networks provide the
ability to spoof the calling party party's telephone number for many
legitimate purposes purposes, including providing network features and
services on the behalf of a legitimate telephone number. However, as we
have seen, bad actors have taken advantage of this ability for
illegitimate and fraudulent purposes meant to trick telephone users
to believe
into believing that they are someone they are not. This problem can
be extended to many emerging forms of personal communications.

This document defines a method for creating and validating a token
that cryptographically verifies an originating identity, or identity or, more
generally
generally, a URI or telephone number representing the originator of
personal communications. Through the extensions defined in Section 8
of this document, in Section 8, other information relevant to the personal
communications can also be added to the token. The goal of PASSporT
is to provide a common framework for signing information related to
the originating identity
related information in an extensible way. Additionally, this
functionality is independent of any specific personal communications
signaling call logic, logic for
personal-communications signaling, so that the assertion of
information related to the originating identity
related information can be implemented in
a flexible way and can be used in such applications including as end-to-end
applications that require different signaling protocols or gateways
between different communications systems. It is anticipated that
guidance specific to the signaling protocol
specific guidance will be provided in other
related documents and specifications to specify how to use and
transport PASSporT tokens,
however PASSporTs; however, this is intentionally out of scope for
this document.

[I-D.ietf-stir-rfc4474bis]

[RFC8224] provides details of the use of PASSporT within the SIP
[RFC3261] signaling protocol for the signing and verification of
telephone numbers and SIP URIs.

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

3. PASSporT Token Overview

JSON

"JSON Web Token (JWT) [RFC7519] and JSON (JWT)" [RFC7519], "JSON Web Signature (JWS) [RFC7515] (JWS)"
[RFC7515], and other related specifications define a standard token
format that can be used as a way of encapsulating claimed or asserted
information with an associated digital signature using X.509 based X.509-based
certificates. JWT provides a set of claims in JSON format that can
conveniently accommodate asserted originating identity originating-identity information
and is that are easily extensible for use in the extension mechanisms
defined below. Additionally, JWS provides a path for updating
methods and cryptographic algorithms used for the associated digital
signatures.

JWS defines the use of JSON data structures in a specified canonical
format for signing data corresponding to JOSE header, the JSON Object Signing and
Encryption (JOSE) Header, JWS Payload, and JWS Signature. JWT
defines a set of claims that are represented by specified JSON
objects which that can be extended with custom keys for specific
applications. The next sections define the header and claims that
MUST be minimally used with JWT and JWS for PASSporT.

PASSporT specifically uses this token format and defines claims that
convey the identity of the origination and destination of personal
communications. The originating identity, the primary value asserted in a PASSporT object represents is
the originating identity representing the identity of the calling
party or the initiator of a personal communications personal-communications session. The
signer of a PASSporT object may or may not correspond to the origination
originating identity. For a given application's use or using
protocol of
PASSporT PASSporT, the creation of the PASSporT object is
performed by an entity that is authoritative to assert the callers caller's
identity. This authority is represented by the certificate
credentials and the
signature signature, and the PASSporT object is created and
initiated to the destination(s) at per the applications application's choice of
authoritative point(s) in the network. For example, the PASSporT
object could be created at a device that has authenticated with a user,
user or at a network entity with an authenticated trust relationship
with that device and it's its user. Destination identities represent the
intended destination of the personal communications, i.e. i.e., the
identity(s) being called by the caller. The destination point(s) point or
points determined by the application need to have the capability to
verify the PASSporT token and the digital signature. The PASSporT PASSporT-
associated certificate is used to validate the authority of the
originating signer, generally via a certificate chain to the trust
anchor for that application.

4. PASSporT Header

The JWS token header is a JOSE header, [RFC7515] Header ([RFC7515], Section 4, 4) that
defines the type and encryption algorithm used in the token.

The PASSporT header should include, at a minimum, the header parameters Header
Parameters defined in the next three subsections.

4.1. "typ" (Type) Header Parameter

The "typ" (Type) Header Parameter is defined in JWS [RFC7515] ([RFC7515],
Section 4.1.9. 4.1.9) to declare the media type of the complete JWS.

For PASSporT Token the PASSporT, the "typ" header MUST be the string "passport".
This represents signifies that the encoded token is a JWT of type passport. "passport".

4.2. "alg" (Algorithm) Header Parameter

The "alg" (Algorithm) Header Parameter is defined in JWS [RFC7515] ([RFC7515],
Section 4.1.1. 4.1.1). This definition includes the ability to specify the
use of a cryptographic algorithm for the signature part of the JWS.
It also refers to a list of defined "alg" values as part of a
registry established by JSON Web Algorithms (JWA) [RFC7518] ([RFC7518],
Section 3.1. 3.1).

For the creation and verification of PASSporT tokens PASSporTs and their digital
signatures, implementations MUST support ES256 as defined in JWA [RFC7518]
([RFC7518], Section 3.4. 3.4). Implementations MAY support other
algorithms registered in the JSON "JSON Web Signature and Encryption
Algorithms
Algorithms" registry created by [RFC7518]. The contents of that
registry may be updated in the future future, depending on cryptographic
strength requirements guided by current security best practice. practices. The
mandatory-to-support algorithm for PASSporT tokens PASSporTs may likewise be updated
in future updates to this document.

Implementations of PASSporT digital signatures using ES256 as defined
above SHOULD use the deterministic ECDSA if/when Elliptic Curve Digital Signature
Algorithm (ECDSA) if or when supported for the reasons stated in
[RFC6979].

4.3. "x5u" (X.509 URL) Header Parameter

As defined in JWS [RFC7515] ([RFC7515], Section 4.1.5., 4.1.5), the "x5u" header
parameter Header
Parameter defines a URI [RFC3986] referring to the resource for the
X.509 public key certificate or certificate chain [RFC5280]
corresponding to the key used to digitally sign the JWS. Generally,
as defined in JWS [RFC7515] section 4.1.5, ([RFC7515], Section 4.1.5), this would correspond
to an HTTPS or DNSSEC resource using integrity protection.

4.4. Example PASSporT header Header

An example of the header, header would be the following, including the
specified passport type, ES256 algorithm, and a URI referencing the
network location of the certificate needed to validate the PASSporT
signature.

{
"typ":"passport",
"alg":"ES256",
"x5u":"https://cert.example.org/passport.cer"
}

5. PASSporT Payload

The token claims consist of the information which that needs to be verified
at the destination party. These claims follow the definition of a
JWT claim [RFC7519] ([RFC7519], Section 4 4) and are encoded as defined by the
JWS Payload [RFC7515] ([RFC7515], Section 3. 3).

PASSporT defines the use of a standard JWT defined JWT-defined claim as well as
custom claims corresponding to the two parties associated with
personal communications, communications -- the originator and destination destination, as
detailed below.

Any

For PASSporT, any claim names MUST use the US-ASCII ASCII character set. Any
claim values can container contain characters that are outside the US-ASCII ASCII range,
however MUST follow
consistent with the default JSON serialization rules of creating a JWT Claims Set as defined in
[RFC7519]
[RFC7519], Section 7. 7.1.

5.1. JWT defined claims JWT-Defined Claims

5.1.1. "iat" - Issued At claim (Issued At) Claim

The JSON claim MUST include the "iat" [RFC7519] Section 4.1.6 defined (Issued At) claim Issued At. ([RFC7519],
Section 4.1.6). As defined defined, the "iat" claim should be set to the
date and time of issuance of the JWT and MUST indicate the date and
time of the origination of the personal communications. The time
value should be of the NumericDate format as defined in
[RFC7519] [RFC7519],
Section 2 NumericDate. 2. This is included for securing the token against replay
and cut and paste cut-and-paste attacks, as explained further in the security considerations in Section 10. 10
("Security Considerations").

5.2. PASSporT specific claims PASSporT-Specific Claims

5.2.1. Originating and Destination Identity Claims

The origination originating identity and the destination identities identity are represented
by two claims that are required for PASSporT, PASSporT -- the "orig" and "dest"
claims. Both "orig" and "dest" MUST contain claim values that are
identity claim JSON objects where the child claim name represents an
identity type and the claim value is the identity string, both
defined in subsequent subsections. Currently, these identities can
be represented as either telephone numbers or Uniform Resource
Indicators (URIs).

The "orig" claim is a JSON object with the claim name of "orig" and a
claim value which that is a JSON object representing the asserted identity
of any type (currently either "tn" or "uri") of the originator of the
personal communications
personal-communications signaling. There MUST be exactly one "orig"
claim with exactly one identity claim object in a PASSporT object.

Note, as

Note: As explained in Section 3, the originating identity represents
the calling party and may or may not correspond to the authoritative
signer of the token.

The "dest" claim is a JSON object with the claim name of "dest" and
MUST have at least have one identity claim object. The "dest" claim value
is an array containing one or more identity claim JSON objects
representing the destination identities of any type (currently "tn"
or "uri"). If the "dest" claim value array contains both "tn" and
"uri" claim names, the JSON object should list the "tn" array first
and the "uri" array second. Within the "tn" and "uri" arrays, the
identity strings should be put in lexicographical order order, including
the scheme-specific portion of the URI characters.

Note, as

Note: As explained in Section 3, the destination identity represents
the called party and may or may not correspond to the authoritative
party verifying the token signature.

5.2.1.1. "tn" - Telephone Number identity (Telephone Number) Identity

If the originating or destination identity is a telephone number, the
claim name representing the identity MUST be "tn".

The claim value for the "tn" claim is the telephone number and MUST
be canonicalized according to the procedures specified in
[I-D.ietf-stir-rfc4474bis] [RFC8224],
Section 8.3.

5.2.1.2. "uri" - URI identity (URI) Identity

If any of the originating or destination identities is of in the form
URI, of
a URI as defined in [RFC3986], the claim name representing the
identity MUST be "uri" "uri", and the claim value is the URI form of the
identity.

5.2.1.3. Future identity forms Identity Forms

We recognize that in the future there may be other standard
mechanisms for representing identities. The "orig" and "dest" claims
currently support "tn" and "uri" but could be extended in the future
to allow for other identity types with new IANA registered IANA-registered unique
types to represent these forms.

5.2.1.4. Examples

Single originator,

The following is an example of a single originator with telephone
number identity +12155551212, to a single destination, destination with URI
identity 'sip:alice@example.com',
example: "sip:alice@example.com":

{
"dest":{"uri":["sip:alice@example.com"]},
"iat":1443208345,
"orig":{"tn":"12155551212"}
}

Single originator,

The following is an example of a single originator with telephone
number identity +12155551212, to multiple destination identities, identities with
telephone number identity +12125551212 and two URI identities, sip:alice@example.com identities --
"sip:alice@example.com" and
sip:bob@example.com, example: "sip:bob@example.com":

{
"dest":{
"tn":["12125551212"],
"uri":["sip:alice@example.com",
"sip:bob@example.net"]
},
"iat":1443208345,
"orig":{"tn":"12155551212"}
}

5.2.2. "mky" - Media Key claim (Media Key) Claim

Some protocols that use PASSporT may also want to protect media
security keys delivered within their signaling in order to bind those
keys to the identities established in the signaling layers. The
"mky" claim is an optional PASSporT claim defining the assertion of
media key fingerprints carried in SDP the Session Description Protocol
(SDP) [RFC4566] via the "a=fingerprint" attribute [RFC4572] ([RFC4572],
Section 5. 5). This claim can support either a single fingerprint or
multiple fingerprints appearing in a single SDP body corresponding to
one or more media streams offered as defined in
[I-D.ietf-mmusic-4572-update]. [RFC8122].

The "mky" claim MUST be formatted as a JSON object with an array
including that
includes the "alg" and "dig" claims with the corresponding algorithm
and hexadecimal values. If there is more than one fingerprint value
associated with different media streams in SDP, the fingerprint
values MUST be constructed as a JSON array denoted by bracket
characters. square brackets
("[" and "]"). For the "dig" claim, the claim value MUST be the hash
of the hexadecimal value without any colons.

The "mky" claim is a JSON object with a claim name of "mky" and a
claim value of a JSON array denoted by brackets. The "mky" claim
value JSON array MUST be constructed as follows:

1. Take each "a=fingerprint" lines line carried in the SDP.

2. Sort the lines based on the UTF8 UTF-8 [RFC3629] encoding of the
concatenation of the "alg" and "dig" claim value strings.

3. Encode the array in the order of the sorted lines, where each
"mky" array element is a JSON object with two elements
corresponding to the "alg" and "dig" objects, with "alg" first
and "dig" second.

An example claim with the "mky" claim is as follows:

For an SDP offer that includes the following fingerprint values,

a=fingerprint:sha-256 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:
5D:49:6B:19:E5:7C:AB:3E:4B:65:2E:7D:46:3F:54:42:CD:54:F1
a=fingerprint:sha-256 02:1A:CC:54:27:AB:EB:9C:53:3F:3E:4B:65
:2E:7D:46:3F:54:42:CD:54:F1:7A:03:A2:7D:F9:B0:7F:46:19:B2

the PASSporT Payload object would be:

{
"dest":{"uri":["sip:alice@example.com"]},
"iat":1443208345,
"mky":[
{
"alg":"sha-256",
"dig":"021ACC5427ABEB9C533F3E4B652E7D463F5442CD54
F17A03A27DF9B07F4619B2"
},
{
"alg":"sha-256",
"dig":"4AADB9B13F82183B540212DF3E5D496B19E57C
AB3E4B652E7D463F5442CD54F1"
}
],
"orig":{"tn":"12155551212"}
}

6. PASSporT Signature

The signature of the PASSporT is created as specified by JWS
[RFC7515]
([RFC7515], Section 5.1 5.1, Steps 1 through 6. 6). PASSporT MUST use the
JWS Protected Header. For the JWS Payload and the JWS Protected
Header, however, the lexicographic ordering and white space whitespace rules
described in
Section Sections 4 and Section 5, 5 of this document, and the JSON
serialization rules in Section 9 of this document document, MUST be followed.

Appendix A of this document has a detailed example of how to follow
the steps to create the JWS Signature.

JWS [RFC7515] Section 5.1

Step 7 JWS of the JSON serialization procedure in [RFC7515], Section 5.1
is not supported for PASSporT.

JWS [RFC7515]

[RFC7515], Section 5.1 5.1, Step 8 describes the method to create the
final JWS Compact Serialization form of the PASSporT Token. PASSporT.

7. Compact form Form of PASSporT

For a using protocol of PASSporT, the PASSporT Claims claims as well as the
PASSporT Header header may include redundant or default information that
could be reconstructed at the destination based on information
provided in the signaling protocol transporting the PASSporT object.
In this case, it may be advantageous to have a more compact form of
PASSporT to save the transmission of the bytes needed to represent
the header and claims.

This specification defines the compact form of the PASSporT token, PASSporT, in the
spirit of the form defined in [RFC7515] [RFC7515], Appendix F, with the use of
'..',
two periods ("..") to represent the header and claim objects being
removed, followed by the PASSporT signature as defined in Section 6,
and the need for the destination to reconstruct the header and claim
objects in order to verify the signature.

In order to construct the Compact compact form of the PASSporT string, the
procedure described in Section 6 MUST be used, with the exception of Step 8
described in JWS [RFC7515]
[RFC7515], Section 5.1. 5.1, Step 8. This step would be replaced by the
following construction of the compact form of PASSporT,
'..' ".." ||
BASE64URL(JWS Signature).

The using protocol of the compact form of PASSporT MUST be
accompanied by a specification for how the header and claims objects
can be reconstructed from information in the signaling protocol being
used.

Note that the full form of the PASSporT token, PASSporT, containing the entire
header, payload, and signature, should also use the lexicographic
ordering and white space whitespace serialization rules, particularly in the case
where some using protocols or interworking between protocols may
require switching between full and compact forms and maintaining the
integrity of the signature.

7.1. Example Compact form Form of PASSporT Token

The compact form of the following example token (with line breaks
between period periods used for readability purposes only)

eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1IjoiaHR0cHM6Ly9j
ZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9
.
eyJkZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdCI
6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0
.
rq3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYsojN
CpTzO3QfPOlckGaS6hEck7w

would be as follows (with line breaks between period used for
readability purposes only) follows:

..rq3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYsojN
CpTzO3QfPOlckGaS6hEck7w

8. Extending PASSporT

PASSporT includes the bare minimum bare-minimum set of claims needed to securely
assert the originating identity and support the secure properties
discussed in various parts of this document. JWT supports a straight
forward
straightforward way to add additional asserted or signed information
by simply adding new claims. PASSporT can be extended beyond the
defined base set of claims to represent other information requiring
assertion or validation beyond the originating identity itself as
needed.

8.1. "ppt" (PASSporT) header parameter Header Parameter

Any using protocol can extend the payload of PASSporT with additional
JWT claims. JWT claims are managed by an existing the "JSON Web Token Claims"
IANA registry as defined in [RFC7519] [RFC7519], Section 10.1. Implementations
of PASSporT MUST support the baseline claims defined in Section 5.2, 5.2
and MAY support extended claims. If it is necessary for an extension
to PASSporT to require that a relying party support a particular
extended claim or set of claims in the PASSporT object, it can do so
by specifying a "ppt" element for the PASSporT JOSE header. Header. All
values of "ppt" need to be defined in a specification which that associates
the new value of the "ppt" element with the required claims and
behaviors. Relying parties MUST fail to validate PASSporT objects
containing an unsupported "ppt".

Using protocols MUST explicitly define the how they carry each claim is carried
in the using protocol and
the rules for how the header and payload objects are constructed
beyond the lexicographical and serialization rules defined in this
document.

Using protocols that carry the compact form of PASSporT, defined in
Section 7, form of PASSporT (Section 7)
instead of the full form MUST use only mandatory extensions signaled
with "ppt" - -- if a using protocol were to add additional optional
claims to a PASSporT object it carried in compact form, relying
parties would have no way to reconstruct the token. Moreover, using
protocols that support the compact form of PASSporT MUST have some
field to signal "ppt" to relying parties, as the compact form of
PASSporT omits the JOSE header. Header.

8.2. Example extended Extended PASSporT header Header

An example header with a PASSporT extension type of "foo" is as
follows:

{
"alg":"ES256",
"ppt":"foo",
"typ":"passport",
"x5u":"https://tel.example.org/passport.cer"
}

8.3. Extended PASSporT Claims

Specifications that define extensions to the PASSporT mechanism MUST
explicitly specify what claims they include beyond the base set of
claims from this document, the order in which they will appear, and
any further information necessary to implement the extension. All
extensions MUST include the baseline PASSporT claim elements
specified in Section 5; claims may only be appended to the claims
object specified; they can never be removed or re-ordered. reordered. Specifying
new claims follows the baseline JWT procedures ([RFC7519] ([RFC7519],
Section 10.1). Understanding an extension or new claims defined by
the extension on the destination verification of the PASSporT token is
optional. The creator of a PASSporT object cannot assume that
destination systems will understand any given extension.
Verification of PASSporT tokens PASSporTs by destination systems that do support an
extension may then trigger appropriate application-level behavior in
the presence of an extension; authors of extensions should provide
appropriate extension-specific guidance to application developers on
this point.

An example set of extended claims, extending the first example in
Section 5.2.1.4 using "bar" as the newly defined claim claim, would be as
follows:

{
"bar":"beyond all recognition"
"dest":{"uri":["sip:alice@example.com"]},
"iat":1443208345,
"orig":{"tn":"12155551212"}
}

9. Deterministic JSON Serialization

JSON objects can include spaces and line breaks, and key value pairs
can occur in any order. It is therefore a non-deterministic string
format. In order to make the digital signature verification work
deterministically, the JSON representation of the JWS Protected
Header object and JWS Payload object MUST be computed as follows.

The JSON object MUST follow the following rules. These rules are
based on the thumbprint of a JSON Web Key (JWK) as defined in
Section 3 Step 1 of [RFC7638].

1. The JSON object MUST contain no whitespace or line breaks before
or after any syntactic elements.

2. JSON objects MUST have the keys ordered lexicographically by the
Unicode [UNICODE] code points of the member names.

3. JSON value literals MUST be lowercase.

4. JSON numbers are to be encoded as integers unless the field is
defined to be encoded otherwise.

5. Encoding rules MUST be applied recursively to member values and
array values.

Note: For any PASSporT extension claims, member names within the
scope of a JSON object MUST NOT be equal to other member names,
otherwise names;
otherwise, serialization will not be deterministic.

9.1. Example PASSport deterministic PASSporT Deterministic JSON form Form

This section demonstrate demonstrates the deterministic JSON serialization for
the example PASSporT Payload shown in Section 5.2.1.4.

The initial JSON object is shown here:

{
"dest":{"uri":["sip:alice@example.com"]},
"orig":{"tn":"12155551212"}
"iat":1443208345,
"mky":[
{
"alg":"sha-256",
"dig":"021ACC5427ABEB9C533F3E4B652E7D463F5442CD54
F17A03A27DF9B07F4619B2"
},
{
"alg":"sha-256",
"dig":"4AADB9B13F82183B540212DF3E5D496B19E57C
AB3E4B652E7D463F5442CD54F1"
}
],
}

The parent members of the JSON object are as follows:

o "dest"

o "orig"

o "iat"

o "mky"

Their lexicographic order is:

o "dest"

o "iat"

o "mky"

o "orig"
The final constructed deterministic JSON serialization
representation, with whitespace and line breaks removed, removed (with line
breaks used for display purposes only) only), is:

{"dest":{"uri":["sip:alice@example.com"],"iat":1443208345,"mky":
[{"alg":"sha-256","dig":"021ACC5427ABEB9C533F3E4B652E7D463F5442CD5
4F17A03A27DF9B07F4619B2"},{"alg":"sha-256","dig":"4AADB9B13F82183B5
40212DF3E5D496B19E57CAB3E4B652E7D463F5442CD54F1"}],
"orig":{"tn":"12155551212"}}

10. Security Considerations

10.1. Avoidance of replay and cut Replay and paste attacks Cut-and-Paste Attacks

There are a number of security considerations for regarding the use of
the token for the avoidance of replay and cut and paste cut-and-paste attacks. PASSporT tokens
PASSporTs SHOULD only be sent with application level application-level protocol
information (e.g. (e.g., for SIP SIP, an INVITE as defined in [RFC3261])
corresponding to the required fields in the token. A uniqueness of the unique set of
token claims and token signature is constructed using the originating
identity being asserted with the 'orig' "orig" claim along with the
following two claims:

o 'iat' The "iat" claim should correspond to a date/time that the message
was originated. It should also be within a relative time that is
reasonable for clock drift and transmission time characteristics
associated with the application using the PASSporT token. PASSporT. Therefore,
validation of the token should consider date and time correlation,
which could be influenced by usage specific to the signaling
protocol
specific use and by network time differences.

o 'dest' The "dest" claim is included to prevent further restrict the valid re-use use of a
previously originated message to send
valid PASSporT being sent as a replay attack to another other destination
party.
parties. The verification of the PASSporT at the destination
should verify that the "dest" claim matches the destination party
as the intended recipient of the message.

10.2. Solution Considerations

The use of PASSporT tokens PASSporTs based on the validation of the digital signature
and the associated certificate requires consideration of the
authentication and authority or reputation of the signer to attest to
the identity being asserted. The following considerations should be
recognized when using PASSporT:

o The use of this token should not, in it's its own right, be considered
a full solution for absolute non-repudiation of the identity being
asserted.

o In many applications, the signer and the end user represented by
the asserted identity represents and signer may not be one in and the same. For example,
when a service provider signs and validates the token on
the behalf of
the user consuming the service, the provider MUST have an
authenticated and secure relationship with the end user or the
device initiating and terminating the communications signaling.

o Applications that use PASSporT should ensure that the verification
of the signature includes the a means of for verifying that the signer is
authoritative through the use of an application application-specific or service
specific
service-specific set of common trust anchors for the application.

11. IANA Considerations

11.1. Media Type Registration

11.1.1. Media Type Registry Contents Additions Requested

This section registers the "application/passport" media type (see
[RFC2046] for the definition of "media type") in the "Media Types"
registry in the manner described in [RFC6838], which can be used to indicate that the
content is a
PASSporT defined PASSporT-defined JWT.

o Type name: application

o Subtype name: passport

o Required parameters: n/a N/A

o Optional parameters: n/a N/A

o Encoding considerations: 8bit; application/passport values are
encoded as a series of base64url-encoded values (some of which may
be the empty string) separated by period ('.') characters.. (".") characters.

o Security considerations: See the Security Considerations
Section section
of [RFC7515].

o Interoperability considerations: n/a N/A

o Published specification: [RFCThis] RFC 8225

o Applications that use this media type: STIR Secure Telephone Identity
Revisited (STIR) and other applications that require identity related
identity-related assertion

o Fragment identifier considerations: n/a N/A

o Additional information:

Magic number(s): n/a N/A

File extension(s): n/a N/A

Macintosh file type code(s): n/a N/A

o Person & email address to contact for further information: Chris
Wendt, chris-ietf@chriswendt.net

o Intended usage: COMMON

o Restrictions on usage: none

o Author: Chris Wendt, chris-ietf@chriswendt.net Wendt <chris-ietf@chriswendt.net>

o Change Controller: IESG

o Provisional registration? No

11.2. JSON Registrations in "JSON Web Token Claims Registration

11.2.1. Registry Contents Additions Requested

o Claims"

Claim Name: "orig"

o
Claim Description: Originating Identity String

o
Change Controller: IESG

o Specification Document(s):
Reference: Section 5.2.1 of [RFCThis]

o RFC 8225

Claim Name: "dest"

o
Claim Description: Destination Identity String

o
Change Controller: IESG

o Specification Document(s):
Reference: Section 5.2.1 of [RFCThis]

o RFC 8225

Claim Name: "mky"

o
Claim Description: Media Key Fingerprint String
o
Change Controller: IESG

o Specification Document(s):
Reference: Section 5.2.2 of [RFCThis] RFC 8225

11.3. JSON Registration in "JSON Web Signature and Encryption Header Parameter Registry

11.3.1. Registry Contents Additions Requested
Parameters"

Header Parameter Name: "ppt"

o
Header Parameter Description: PASSporT extension identifier

o
Header Parameter Usage Location(s): JWS

o
Change Controller: IESG

o Specification Document(s):
Reference: Section 8.1 of [RFCThis] RFC 8225

11.4. PASSporT Extension Extensions Registry Request

The IANA is requested to create has created a new PASSporT Type registry for
'ppt' "ppt" parameter
values. That parameter and its values are defined in Section 8.1.
New registry entries must contain the name of the 'ppt'
parameter value and the specification in which the value is
described. The policy for this registry is Specification Required.

12. Acknowledgements

Particular thanks to members of the ATIS and SIP Forum NNI Task Group
including Jim McEchern, Martin Dolly, Richard Shockey, John Barnhill,
Christer Holmberg, Victor Pascual Avila, Mary Barnes, Eric Burger for
their review, ideas, and contributions also thanks to Henning
Schulzrinne, Russ Housley, Alan Johnston, Richard Barnes, Mark
Miller, Ted Hardie, Dave Crocker, Robert Sparks, Jim Schaad for
valuable feedback on of the technical "ppt" parameter
value and security aspects of the
document. Additional thanks to Harsha Bellur for assistance specification in
coding which the example tokens.

13. value is described. The
policy for this registry is Specification Required [RFC8126].

12. References

13.1.

12.1. Normative References

[I-D.ietf-mmusic-4572-update]
Lennox, J. and C. Holmberg, "Connection-Oriented Media
Transport over TLS in SDP", draft-ietf-mmusic-
4572-update-13 (work in progress), February 2017.

[I-D.ietf-stir-rfc4474bis]
Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
"Authenticated Identity Management in the Session
Initiation Protocol (SIP)", draft-ietf-stir-rfc4474bis-15
(work in progress), October 2016.

[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<http://www.rfc-editor.org/info/rfc2046>.
<https://www.rfc-editor.org/info/rfc2046>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
<https://www.rfc-editor.org/info/rfc2119>.

[RFC3629] Yergeau, F., "UTF-8, a transformation format of
ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629,
November 2003, <https://www.rfc-editor.org/info/rfc3629>.

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
<https://www.rfc-editor.org/info/rfc3986>.

[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
July 2006, <http://www.rfc-editor.org/info/rfc4566>. <https://www.rfc-editor.org/info/rfc4566>.

[RFC4572] Lennox, J., "Connection-Oriented Media Transport over the
Transport Layer Security (TLS) Protocol in the Session
Description Protocol (SDP)", RFC 4572,
DOI 10.17487/RFC4572, July 2006,
<http://www.rfc-editor.org/info/rfc4572>.
<https://www.rfc-editor.org/info/rfc4572>.

[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>.
<https://www.rfc-editor.org/info/rfc6838>.

[RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature
Algorithm (DSA) and Elliptic Curve Digital Signature
Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979,
August 2013, <http://www.rfc-editor.org/info/rfc6979>. <https://www.rfc-editor.org/info/rfc6979>.

[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515,
May 2015, <http://www.rfc-editor.org/info/rfc7515>. <https://www.rfc-editor.org/info/rfc7515>.

[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<http://www.rfc-editor.org/info/rfc7518>.
<https://www.rfc-editor.org/info/rfc7518>.

[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
<https://www.rfc-editor.org/info/rfc7519>.

[RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK)
Thumbprint", RFC 7638, DOI 10.17487/RFC7638,
September 2015, <http://www.rfc-editor.org/info/rfc7638>. <https://www.rfc-editor.org/info/rfc7638>.

[RFC8122] Lennox, J. and C. Holmberg, "Connection-Oriented Media
Transport over the Transport Layer Security (TLS) Protocol
in the Session Description Protocol (SDP)", RFC 8122,
DOI 10.17487/RFC8122, March 2017,
<https://www.rfc-editor.org/info/rfc8122>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in
RFC 2119 Key Words", BCP 14, RFC 8174,
DOI 10.17487/RFC8174, May 2017,
<https://www.rfc-editor.org/info/rfc8174>.

[RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
"Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 8224,
DOI 10.17487/RFC8224, February 2018,
<https://www.rfc-editor.org/info/rfc8224>.

[UNICODE] The Unicode Consortium, "The Unicode Standard", June 2016,
<http://www.unicode.org/versions/latest/>.

13.2.

12.2. Informative References

[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>.
<https://www.rfc-editor.org/info/rfc3261>.

[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
<https://www.rfc-editor.org/info/rfc5280>.

[RFC7340] Peterson, J., Schulzrinne, H., and H. Tschofenig, "Secure
Telephone Identity Problem Statement and Requirements",
RFC 7340, DOI 10.17487/RFC7340, September 2014,
<http://www.rfc-editor.org/info/rfc7340>.
<https://www.rfc-editor.org/info/rfc7340>.

[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.

Appendix A. Example ES256 based ES256-Based PASSporT JWS Serialization and
Signature

For PASSporT, there will always be a JWS with the following members:

o "protected", with the value BASE64URL(UTF8(JWS Protected Header))

o "payload", with the value BASE64URL (JWS BASE64URL(JWS Payload)

o "signature", with the value BASE64URL(JWS Signature)

This example will follow the steps in JWS [RFC7515] ([RFC7515], Section 5.1,
steps
Steps 1-6 and 8 and 8); it incorporates the additional serialization steps
required for PASSporT.

Step 1 for JWS references the JWS Payload, an Payload. An example PASSporT
Payload is as follows:

{
"dest":{"uri":["sip:alice@example.com"]}
"iat":1471375418,
"orig":{"tn":"12155551212"}
}

This would be serialized to the following form (with line break used
for display purposes only):

{"dest":{"uri":["sip:alice@example.com"]},"iat":1471375418,
"orig":{"tn":"12155551212"}}

Step 2 Computes computes the BASE64URL(JWS Payload) Payload), producing this value
(with line break used for display purposes only):

eyJkZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdCI
6MTQ3MTM3NTQxOCwib3JpZyI6eyJ0biI6IjEyMTU1NTUxMjEyIn19

For Step 3, an example PASSporT Protected Header comprising the constructed as a
JOSE Header is as follows:

{
"alg":"ES256",
"typ":"passport",
"x5u":"https://cert.example.org/passport.cer"
}
This would be serialized to the following form (with line break used
for display purposes only):

{"alg":"ES256","typ":"passport","x5u":"https://cert.example.org
/passport.cer"}

Step 4 Performs performs the BASE64URL(UTF8(JWS Protected Header)) operation
and encoding produces encoding, producing this value (with line break used for display
purposes only):

eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1IjoiaHR0cHM6Ly9j
ZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9

Step

Steps 5 and Step 6 performs perform the computation of the digital signature of the
PASSporT Signing Input ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.'
"." || BASE64URL(JWS Payload)) Payload)), using ES256 as the algorithm and the
BASE64URL(JWS Signature).

VLBCIVDCaeK6M4hLJb6SHQvacAQVvoiiEOWQ_iUkqk79UD81fHQ0E1b3_GluIkb
a7UWYRM47ZbNFdOJquE35cw

Step 8 describes how to create the final PASSporT token, PASSporT, concatenating the
values in the order Header.Payload.Signature with period ('.') (".")
characters. For the above example values values, this would produce the
following (with line breaks between period periods used for readability
purposes only):

eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1IjoiaHR0cHM6Ly9j
ZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9
.
eyJkZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdCI
6MTQ3MTM3NTQxOCwib3JpZyI6eyJ0biI6IjEyMTU1NTUxMjEyIn19
.
VLBCIVDCaeK6M4hLJb6SHQvacAQVvoiiEOWQ_iUkqk79UD81fHQ0E1b3_GluIkb
a7UWYRM47ZbNFdOJquE35cw

A.1. X.509 Private Key in PKCS#8 format PKCS #8 Format for ES256 Example** Example

A.2. X.509 Public Key for ES256 Example** Example

-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE8HNbQd/TmvCKwPKHkMF9fScavGeH
78YTU8qLS8I5HLHSSmlATLcslQMhNC/OhlWBYC626nIlo7XeebYS7Sb37g==
-----END PUBLIC KEY-----

Acknowledgments

Particular thanks to members of the ATIS and SIP Forum NNI Task
Group, including Jim McEachern, Martin Dolly, Richard Shockey, John
Barnhill, Christer Holmberg, Victor Pascual Avila, Mary Barnes, and
Eric Burger, for their review, ideas, and contributions. Thanks also
to Henning Schulzrinne, Russ Housley, Alan Johnston, Richard Barnes,
Mark Miller, Ted Hardie, Dave Crocker, Robert Sparks, and Jim Schaad
for valuable feedback on the technical and security aspects of the
document. Additional thanks to Harsha Bellur for assistance in
coding the example tokens.

Authors' Addresses

Chris Wendt
Comcast
One Comcast Center
Philadelphia, PA 19103
USA
United States of America

Email: chris-ietf@chriswendt.net

Jon Peterson
Neustar Inc.
1800 Sutter St St. Suite 570
Concord, CA 94520
US
United States of America

Email: jon.peterson@neustar.biz