JWK Thumbprint URIMicrosoftmbj@microsoft.comhttps://self-issued.info/Microsoftkryasuda@microsoft.comhttps://twitter.com/kristinayasuda
Security
OAuth Working GroupRFCRequest for CommentsI-DInternet-DraftJSON Web KeyJWKThumbprintURIURNOAuth
This specification registers a kind of URI that represents
a JSON Web Key (JWK) Thumbprint value.
JWK Thumbprints are defined in RFC 7638.
This enables JWK Thumbprints to be used,
for instance, as key identifiers in contexts requiring URIs.
A JSON Web Key (JWK) Thumbprint
is a URL-safe representation of a hash value over a JSON Web Key (JWK) .
This specification defines a URI prefix indicating that the
portion of the URI following the prefix is a JWK Thumbprint.
This enables JWK Thumbprints to be communicated in contexts requiring URIs,
including in specific JSON Web Token (JWT) claims.
JWK Thumbprints URIs are being used in the specification
as one kind of subject identifier in a context requiring that the identifier be a URI.
In this case, the subject identifier is derived from a public key represented as a JWK.
Expressing the identifier as JWK Thumbprint URI enables this kind of identifier
to be differentiated from other kinds of identifiers that are also URIs,
such as Decentralized Identifiers (DIDs) .
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
BCP 14
when, and only when, they appear in all capitals, as shown here.
The following URI prefix is defined to indicate that the
portion of the URI following the prefix is a JWK Thumbprint:
urn:ietf:params:oauth:jwk-thumbprint
To make it explicit in a URI which hash algorithm is used,
the prefix is followed by a hash algorithm identifier and a JWK Thumbprint value,
each separated by a colon character to form a URI representing a JWK Thumbprint.
Hash algorithm identifiers used in JWK Thumbprint URIs MUST be values from the "Hash Name String" column
in the IANA "Named Information Hash Algorithm" registry .
JWK Thumbprint URIs with hash algorithm identifiers not found in this registry are not considered valid
and applications will need to detect and handle this error, should it occur.
To promote interoperability among implementations,
the SHA-256 hash algorithm is mandatory to implement.
Section 3.1 of contains the following example JWK Thumbprint value:
A complete JWK Thumbprint URI using the above JWK Thumbprint and SHA-256 hash algorithm is:
The security considerations of
also apply when using this specification.
There are cryptographic algorithms for which multiple public keys correspond to the same private key.
This is described in the security considerations of as follows:
Designers using these curves should be aware that for each public
key, there are several publicly computable public keys that are
equivalent to it, i.e., they produce the same shared secrets. Thus
using a public key as an identifier and knowledge of a shared secret
as proof of ownership (without including the public keys in the key
derivation) might lead to subtle vulnerabilities.
This consideration for public keys as identifiers equally applies to JWK Thumbprint URIs used as identifiers.
A recommended way to ensure that the JWK Thumbprint URI corresponds to the actual
public key used is to sign a message containing the correct public key with the private key.
This signed message could also contain the JWK Thumbprint URI
(although, by definition, it could also be computed directly from the public key).
This specification registers the following value in the
IANA "OAuth URI" registry
established by .
URN: urn:ietf:params:oauth:jwk-thumbprintCommon Name: JWK Thumbprint URIChange controller: IESGSpecification Document: [[ this specification ]]OAuth ParametersIANANamed Information Hash Algorithm RegistryIANASelf-Issued OpenID Provider v2MicrosoftMicrosoftDecentralized Identifiers (DIDs) v1.0Digital BazaarDigital BazaarDanube TechEvernym
Use cases for this specification were developed in the
OpenID Connect Working Group of the OpenID Foundation.
Specifically, it is being used a key identifier in the
specification.
The following individuals also contributed to the creation of this specification:
John Bradley,
Scott Bradner,
Brian Campbell,
Roman Danyliw,
Vladimir Dzhuvinov,
Lars Eggert,
Warren Kumari,
Adam Lemmon,
Neil Madden,
James Manger,
Francesca Palombini,
Aaron Parecki,
Gonzalo Salgueiro,
Rifaat Shekh-Yusef,
Robert Sparks,
David Waite,
Robert Wilton,
and
Paul Wouters.
[[ to be removed by the RFC Editor before publication as an RFC ]]
-03
Addressed IESG comment by Lars Eggert on the use of inclusive language.
-02
Addressed IETF last call comments by clarifying the requirement to use registered hash algorithm identifiers.
-01
Added security considerations about multiple public keys coresponding to the same private key.
Added hash algorithm identifier after the JWK thumbprint URI prefix to make it explicit in a URI which hash algorithm is used.
Added reference to a registry for hash algorithm identifiers.
Added SHA-256 as a mandatory to implement hash algorithm to promote interoperability.
-00
Created initial working group draft from draft-jones-oauth-jwk-thumbprint-uri-01.