rfc9278.original   rfc9278.txt 
OAuth Working Group M. Jones Internet Engineering Task Force (IETF) M. Jones
Internet-Draft K. Yasuda Request for Comments: 9278 K. Yasuda
Intended status: Standards Track Microsoft Category: Standards Track Microsoft
Expires: December 3, 2022 Jun 1, 2022 ISSN: 2070-1721 August 2022
JWK Thumbprint URI JWK Thumbprint URI
draft-ietf-oauth-jwk-thumbprint-uri-03
Abstract Abstract
This specification registers a kind of URI that represents a JSON Web This specification registers a kind of URI that represents a JSON Web
Key (JWK) Thumbprint value. JWK Thumbprints are defined in RFC 7638. Key (JWK) Thumbprint value. JWK Thumbprints are defined in RFC 7638.
This enables JWK Thumbprints to be used, for instance, as key This enables JWK Thumbprints to be used, for instance, as key
identifiers in contexts requiring URIs. identifiers in contexts requiring URIs.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9278.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Requirements Notation and Conventions . . . . . . . . . . . . 2 2. Requirements Notation and Conventions
3. JWK Thumbprint URI . . . . . . . . . . . . . . . . . . . . . 3 3. JWK Thumbprint URI
4. Hash Algorithms Identifier . . . . . . . . . . . . . . . . . 3 4. Hash Algorithms Identifier
5. Mandatory to Implement Hash Algorithm . . . . . . . . . . . . 3 5. Mandatory to Implement Hash Algorithm
6. Example JWK Thumbprint URI . . . . . . . . . . . . . . . . . 3 6. Example JWK Thumbprint URI
7. Security Considerations . . . . . . . . . . . . . . . . . . . 3 7. Security Considerations
7.1. Multiple Public Keys per Private Key . . . . . . . . . . 3 7.1. Multiple Public Keys per Private Key
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 8. IANA Considerations
8.1. OAuth URI Registration . . . . . . . . . . . . . . . . . 4 8.1. OAuth URI Registration
8.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 4 8.1.1. Registry Contents
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 9. References
9.1. Normative References . . . . . . . . . . . . . . . . . . 4 9.1. Normative References
9.2. Informative References . . . . . . . . . . . . . . . . . 5 9.2. Informative References
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 5 Acknowledgements
Appendix B. Document History . . . . . . . . . . . . . . . . . . 6 Authors' Addresses
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
A JSON Web Key (JWK) Thumbprint [RFC7638] is a URL-safe A JSON Web Key (JWK) Thumbprint [RFC7638] is a URL-safe
representation of a hash value over a JSON Web Key (JWK) [RFC7517]. representation of a hash value over a JWK [RFC7517]. This
This specification defines a URI prefix indicating that the portion specification defines a URI prefix indicating that the portion of the
of the URI following the prefix is a JWK Thumbprint. This enables URI following the prefix is a JWK Thumbprint. This enables JWK
JWK Thumbprints to be communicated in contexts requiring URIs, Thumbprints to be communicated in contexts requiring URIs, including
including in specific JSON Web Token (JWT) [RFC7519] claims. in specific JSON Web Token (JWT) [RFC7519] claims.
JWK Thumbprints URIs are being used in the [SIOPv2] specification as JWK Thumbprint URIs are being used in the [SIOPv2] specification as
one kind of subject identifier in a context requiring that the one kind of subject identifier in a context requiring that the
identifier be a URI. In this case, the subject identifier is derived identifier be a URI. In this case, the subject identifier is derived
from a public key represented as a JWK. Expressing the identifier as from a public key represented as a JWK. Expressing the identifier as
JWK Thumbprint URI enables this kind of identifier to be a JWK Thumbprint URI enables this kind of identifier to be
differentiated from other kinds of identifiers that are also URIs, differentiated from other kinds of identifiers that are also URIs,
such as Decentralized Identifiers (DIDs) [DID-Core]. such as Decentralized Identifiers (DIDs) [DID-Core].
2. Requirements Notation and Conventions 2. Requirements Notation and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. JWK Thumbprint URI 3. JWK Thumbprint URI
The following URI prefix is defined to indicate that the portion of The following URI prefix is defined to indicate that the portion of
the URI following the prefix is a JWK Thumbprint: the URI following the prefix is a JWK Thumbprint:
o "urn:ietf:params:oauth:jwk-thumbprint" urn:ietf:params:oauth:jwk-thumbprint
To make it explicit in a URI which hash algorithm is used, the prefix To make the hash algorithm being used explicit in a URI, the prefix
is followed by a hash algorithm identifier and a JWK Thumbprint is followed by a hash algorithm identifier and a JWK Thumbprint
value, each separated by a colon character to form a URI representing value, each separated by a colon character to form a URI representing
a JWK Thumbprint. a JWK Thumbprint.
4. Hash Algorithms Identifier 4. Hash Algorithms Identifier
Hash algorithm identifiers used in JWK Thumbprint URIs MUST be values Hash algorithm identifiers used in JWK Thumbprint URIs MUST be values
from the "Hash Name String" column in the IANA "Named Information from the "Hash Name String" column in the IANA "Named Information
Hash Algorithm" registry [IANA.Hash.Algorithms]. JWK Thumbprint URIs Hash Algorithm Registry" [IANA.Hash.Algorithms]. JWK Thumbprint URIs
with hash algorithm identifiers not found in this registry are not with hash algorithm identifiers not found in this registry are not
considered valid and applications will need to detect and handle this considered valid and applications will need to detect and handle this
error, should it occur. error, should it occur.
5. Mandatory to Implement Hash Algorithm 5. Mandatory to Implement Hash Algorithm
To promote interoperability among implementations, the SHA-256 hash To promote interoperability among implementations, the SHA-256 hash
algorithm is mandatory to implement. algorithm is mandatory to implement.
6. Example JWK Thumbprint URI 6. Example JWK Thumbprint URI
Section 3.1 of [RFC7638] contains the following example JWK Section 3.1 of [RFC7638] contains the following example JWK
Thumbprint value: Thumbprint value:
NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs
A complete JWK Thumbprint URI using the above JWK Thumbprint and A complete JWK Thumbprint URI using the above JWK Thumbprint and
SHA-256 hash algorithm is: SHA-256 hash algorithm is as follows:
urn:ietf:params:oauth:jwk-thumbprint:sha-256:NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs urn:ietf:params:oauth:jwk-thumbprint:sha-256:NzbLsXh8uDCcd-
6MNwXF4W_7noWXFZAfHkxZsRGC9Xs
7. Security Considerations 7. Security Considerations
The security considerations of [RFC7638] also apply when using this The security considerations of [RFC7638] also apply when using this
specification. specification.
7.1. Multiple Public Keys per Private Key 7.1. Multiple Public Keys per Private Key
There are cryptographic algorithms for which multiple public keys There are cryptographic algorithms for which multiple public keys
correspond to the same private key. This is described in the correspond to the same private key. This is described in the
security considerations of [RFC7748] as follows: security considerations of [RFC7748] as follows:
Designers using these curves should be aware that for each public | Designers using these curves should be aware that for each public
key, there are several publicly computable public keys that are | key, there are several publicly computable public keys that are
equivalent to it, i.e., they produce the same shared secrets. | equivalent to it, i.e., they produce the same shared secrets.
Thus using a public key as an identifier and knowledge of a shared | Thus using a public key as an identifier and knowledge of a shared
secret as proof of ownership (without including the public keys in | secret as proof of ownership (without including the public keys in
the key derivation) might lead to subtle vulnerabilities. | the key derivation) might lead to subtle vulnerabilities.
This consideration for public keys as identifiers equally applies to This consideration for public keys as identifiers equally applies to
JWK Thumbprint URIs used as identifiers. A recommended way to ensure JWK Thumbprint URIs used as identifiers. A recommended way to ensure
that the JWK Thumbprint URI corresponds to the actual public key used that the JWK Thumbprint URI corresponds to the actual public key used
is to sign a message containing the correct public key with the is to sign a message containing the correct public key with the
private key. This signed message could also contain the JWK private key. This signed message could also contain the JWK
Thumbprint URI (although, by definition, it could also be computed Thumbprint URI (although, by definition, it could also be computed
directly from the public key). directly from the public key).
8. IANA Considerations 8. IANA Considerations
8.1. OAuth URI Registration 8.1. OAuth URI Registration
This specification registers the following value in the IANA "OAuth This specification registers the following value in the IANA "OAuth
URI" registry [IANA.OAuth.Parameters] established by [RFC6755]. URI" registry [IANA.OAuth.Parameters] established by [RFC6755].
8.1.1. Registry Contents 8.1.1. Registry Contents
o URN: urn:ietf:params:oauth:jwk-thumbprint URN: urn:ietf:params:oauth:jwk-thumbprint
o Common Name: JWK Thumbprint URI
o Change controller: IESG Common Name: JWK Thumbprint URI
o Specification Document: [[ this specification ]]
Change controller: IESG
Specification Document: RFC 9278
9. References 9. References
9.1. Normative References 9.1. Normative References
[IANA.OAuth.Parameters] [IANA.OAuth.Parameters]
IANA, "OAuth Parameters", IANA, "OAuth Parameters",
<http://www.iana.org/assignments/oauth-parameters>. <http://www.iana.org/assignments/oauth-parameters>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
skipping to change at page 5, line 11 skipping to change at line 194
[RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK) [RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK)
Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September
2015, <https://www.rfc-editor.org/info/rfc7638>. 2015, <https://www.rfc-editor.org/info/rfc7638>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 9.2. Informative References
[DID-Core] [DID-Core] Sporny, M., Guy, A., Sabadello, M., and D. Reed,
Sporny, M., Guy, A., Sabadello, M., and D. Reed, "Decentralized Identifiers (DIDs) v1.0", August 2021,
"Decentralized Identifiers (DIDs) v1.0", Aug 2021,
<https://www.w3.org/TR/2021/PR-did-core-20210803/>. <https://www.w3.org/TR/2021/PR-did-core-20210803/>.
[IANA.Hash.Algorithms] [IANA.Hash.Algorithms]
IANA, "Named Information Hash Algorithm Registry", IANA, "Named Information Hash Algorithm Registry",
<https://www.iana.org/assignments/named-information/named- <https://www.iana.org/assignments/named-information>.
information.xhtml#hash-alg>.
[RFC6755] Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace [RFC6755] Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace
for OAuth", RFC 6755, DOI 10.17487/RFC6755, October 2012, for OAuth", RFC 6755, DOI 10.17487/RFC6755, October 2012,
<https://www.rfc-editor.org/info/rfc6755>. <https://www.rfc-editor.org/info/rfc6755>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517, [RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015, DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/info/rfc7517>. <https://www.rfc-editor.org/info/rfc7517>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>. <https://www.rfc-editor.org/info/rfc7519>.
[RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves [RFC7748] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
for Security", RFC 7748, DOI 10.17487/RFC7748, January for Security", RFC 7748, DOI 10.17487/RFC7748, January
2016, <https://www.rfc-editor.org/info/rfc7748>. 2016, <https://www.rfc-editor.org/info/rfc7748>.
[SIOPv2] Yasuda, K. and M. B. Jones, "Self-Issued OpenID Provider [SIOPv2] Yasuda, K., Jones, M., and T. Lodderstedt, "Self-Issued
v2", December 2021, <https://openid.net/specs/openid- OpenID Provider v2", June 2022, <https://openid.net/specs/
connect-self-issued-v2-1_0.html>. openid-connect-self-issued-v2-1_0.html>.
Appendix A. Acknowledgements Acknowledgements
Use cases for this specification were developed in the OpenID Connect Use cases for this specification were developed in the OpenID Connect
Working Group of the OpenID Foundation. Specifically, it is being Working Group of the OpenID Foundation. Specifically, it is being
used a key identifier in the [SIOPv2] specification. used as a key identifier in the [SIOPv2] specification.
The following individuals also contributed to the creation of this The following individuals also contributed to the creation of this
specification: John Bradley, Scott Bradner, Brian Campbell, Roman specification: John Bradley, Scott Bradner, Brian Campbell, Roman
Danyliw, Vladimir Dzhuvinov, Lars Eggert, Warren Kumari, Adam Lemmon, Danyliw, Vladimir Dzhuvinov, Lars Eggert, Warren Kumari, Adam Lemmon,
Neil Madden, James Manger, Francesca Palombini, Aaron Parecki, Neil Madden, James Manger, Francesca Palombini, Aaron Parecki,
Gonzalo Salgueiro, Rifaat Shekh-Yusef, Robert Sparks, David Waite, Gonzalo Salgueiro, Rifaat Shekh-Yusef, Robert Sparks, David Waite,
Robert Wilton, and Paul Wouters. Robert Wilton, and Paul Wouters.
Appendix B. Document History
[[ to be removed by the RFC Editor before publication as an RFC ]]
-03
o Addressed IESG comment by Lars Eggert on the use of inclusive
language.
-02
o Addressed IETF last call comments by clarifying the requirement to
use registered hash algorithm identifiers.
-01
o Added security considerations about multiple public keys
coresponding to the same private key.
o Added hash algorithm identifier after the JWK thumbprint URI
prefix to make it explicit in a URI which hash algorithm is used.
o Added reference to a registry for hash algorithm identifiers.
o Added SHA-256 as a mandatory to implement hash algorithm to
promote interoperability.
-00
o Created initial working group draft from draft-jones-oauth-jwk-
thumbprint-uri-01.
Authors' Addresses Authors' Addresses
Michael B. Jones Michael B. Jones
Microsoft Microsoft
Email: mbj@microsoft.com Email: mbj@microsoft.com
URI: https://self-issued.info/ URI: https://self-issued.info/
Kristina Yasuda Kristina Yasuda
Microsoft Microsoft
Email: kryasuda@microsoft.com Email: kryasuda@microsoft.com
URI: https://twitter.com/kristinayasuda URI: https://twitter.com/kristinayasuda
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