OAuth Working Group B. Campbell
Internet-Draft Ping Identity
Intended status: Standards Track J. Bradley
Expires: January 28, 2018 Yubico
N. Sakimura
Nomura Research Institute
T. Lodderstedt
YES Europe AG
July 27, 2017
Mutual TLS Profile for OAuth 2.0
draft-ietf-oauth-mtls-03
Abstract
This document describes Transport Layer Security (TLS) mutual
authentication using X.509 certificates as a mechanism for OAuth
client authentication to the token endpoint as well as for
certificate bound sender constrained access tokens.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on January 28, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Notation and Conventions . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Mutual TLS for Client Authentication . . . . . . . . . . . . 4
2.1. Mutual TLS Client Authentication to the Token Endpoint . 4
2.2. Authorization Server Metadata . . . . . . . . . . . . . . 5
2.3. Dynamic Client Registration . . . . . . . . . . . . . . . 5
3. Mutual TLS Sender Constrained Resources Access . . . . . . . 6
3.1. X.509 Certificate SHA-256 Thumbprint Confirmation Method
for JWT . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2. Confirmation Method for Token Introspection . . . . . . . 8
4. Implementation Considerations . . . . . . . . . . . . . . . . 9
4.1. Authorization Server . . . . . . . . . . . . . . . . . . 9
4.2. Resource Server . . . . . . . . . . . . . . . . . . . . . 9
4.3. Sender Constrained Access Tokens Without Client
Authentication . . . . . . . . . . . . . . . . . . . . . 10
4.4. Certificate Bound Access Tokens . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5.1. JWT Confirmation Methods Registration . . . . . . . . . . 10
5.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 10
5.2. OAuth Authorization Server Metadata Registration . . . . 11
5.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 11
5.3. Token Endpoint Authentication Method Registration . . . . 11
5.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 11
5.4. OAuth Token Introspection Response Registration . . . . . 11
5.4.1. Registry Contents . . . . . . . . . . . . . . . . . . 11
5.5. OAuth Dynamic Client Registration Metadata Registration . 12
5.5.1. Registry Contents . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6.1. TLS Versions and Best Practices . . . . . . . . . . . . . 12
6.2. X.509 Certificate Spoofing . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15
Appendix B. Document(s) History . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
This document describes Transport Layer Security (TLS) mutual
authentication using X.509 certificates as a mechanism for OAuth
client authentication to the token endpoint as well as for sender
constrained access to OAuth protected resources.
The OAuth 2.0 Authorization Framework [RFC6749] defines a shared
secret method of client authentication but also allows for the
definition and use of additional client authentication mechanisms
when interacting with the authorization server's token endpoint.
This document describes an additional mechanism of client
authentication utilizing mutual TLS [RFC5246] certificate-based
authentication, which provides better security characteristics than
shared secrets.
Mutual TLS sender constrained access to protected resources ensures
that only the party in possession of the private key corresponding to
the certificate can utilize the access token to get access to the
associated resources. Such a constraint is unlike the case of the
basic bearer token described in [RFC6750], where any party in
possession of the access token can use it to access the associated
resources. Mutual TLS sender constrained access binds the access
token to the client's certificate thus preventing the use of stolen
access tokens or replay of access tokens by unauthorized parties.
Mutual TLS sender constrained access tokens and mutual TLS client
authentication are distinct mechanisms that don't necessarily need to
be deployed together.
1.1. Requirements Notation and Conventions
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].
1.2. Terminology
This specification uses the following phrases interchangeably:
Transport Layer Security (TLS) Mutual Authentication
Mutual TLS
These phrases all refer to the process whereby a client uses it's
X.509 certificate to authenticate itself with a server when
negotiating a TLS session. In TLS 1.2 [RFC5246] this requires the
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client to send Client Certificate and Certificate Verify messages
during the TLS handshake and for the server to verify these messages.
2. Mutual TLS for Client Authentication
2.1. Mutual TLS Client Authentication to the Token Endpoint
The following section defines, as an extension of OAuth 2.0,
Section 2.3 [RFC6749], the use of mutual TLS X.509 client
certificates as client credentials. The requirement of mutual TLS
for client authentications is determined by the authorization server
based on policy or configuration for the given client (regardless of
whether the client was dynamically registered or statically
configured or otherwise established). OAuth 2.0 requires that access
token requests by the client to the token endpoint use TLS. In order
to utilize TLS for client authentication, the TLS connection MUST
have been established or reestablished with mutual X.509 certificate
authentication (i.e. the Client Certificate and Certificate Verify
messages are sent during the TLS Handshake [RFC5246]).
For all access token requests to the token endpoint, regardless of
the grant type used, the client MUST include the "client_id"
parameter, described in OAuth 2.0, Section 2.2 [RFC6749]. The
presence of the "client_id" parameter enables the authorization
server to easily identify the client independently from the content
of the certificate and allows for trust models to vary as appropriate
for a given deployment. The authorization server can locate the
client configuration by the client identifier and check the
certificate presented in the TLS Handshake against the expected
credentials for that client. The authorization server MUST enforce
some method of binding a certificate to a client. The following two
binding methods are defined:
PKI The PKI method uses a distinguished name (DN) to identify the
client. The TLS handshake is utilized to validate the client's
possession of the private key corresponding to the public key in
the certificate and to validate the corresponding certificate
chain. The client is successfully authenticated if the subject
information in the certificate matches the configured DN. The
client may prescribe the DN of the issuer of its certificates.
The authorization server will enforce this restriction after the
TLS handshake took place. Setting the issuer to a certain CA
securely scopes the DN of the client to this CA and shall prevent
an attacker from impersonating a client by using a certificate for
the client's DN obtained from a different CA. The PKI method
facilitates the way X.509 certificates are traditionally being
used for authentication. It also allows the client to rotate its
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X.509 certificates without the need to modify its respective
authentication data at the authorization server.
Public Key The Public Key method uses public keys to identify
clients. As pre-requisite, the client registers a X.509
certificate or a trusted source for its X.509 certificates (jwks
uri as defined in [RFC7591]) with the authorization server.
During authentication, TLS is utilized to validate the client's
possession of the private key corresponding to the public key
presented in the respective TLS handshake. In contrast to the PKI
method, the certificate chain is not validated in this case. The
client is successfully authenticated, if the subject public key
info of the validated certificate matches the subject public key
info of one the certificates configured for that particular
client. The Public Key method allows to use mutual TLS to
authenticate clients without the need to maintain a PKI. When
used in conjunction with a trusted X.509 certificate source, it
also allows the client to rotate its X.509 certificates without
the need to change its respective authentication data at the
authorization server.
2.2. Authorization Server Metadata
In authorization server metadata, such as [OpenID.Discovery] and
[I-D.ietf-oauth-discovery], the
"token_endpoint_auth_methods_supported" parameter indicates client
authentication methods to the token endpoint supported by the
authorization server. This document introduces the value
"tls_client_auth" for use in "token_endpoint_auth_methods_supported"
to indicate server support for mutual TLS client authentication
utilizing the PKI method. And for the support of mutual TLS client
authentication utilizing the Public Key method, the value
"pub_key_tls_client_auth" is used in
"token_endpoint_auth_methods_supported".
This document also introduces a new authorization server metadata
parameter:
mutual_tls_sender_constrained_access_tokens
OPTIONAL. Boolean value indicating server support for mutual TLS
sender constrained access tokens. If omitted, the default value
is "false".
2.3. Dynamic Client Registration
This document adds the following values and metadata parameters to
OAuth 2.0 Dynamic Client Registration [RFC7591].
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The client metadata parameter
"mutual_tls_sender_constrained_access_tokens" is a Boolean value used
to indicate the client's intention to use mutual TLS sender
constrained access tokens. If omitted, the default value is "false".
For the PKI method of binding a certificate to a client, the value
"tls_client_auth" is used to indicate the client's intention to use
mutual TLS as an authentication method to the token endpoint for the
"token_endpoint_auth_method" client metadata parameter. And the
following two metadata parameters are introduced in support of the
PKI method of binding a certificate to a client:
tls_client_auth_subject_dn
An [RFC4514] string representation of the expected subject
distinguished name of the certificate the OAuth client will use in
mutual TLS authentication.
tls_client_auth_root_dn
OPTIONAL. An [RFC4514] string representation of a distinguished
name that can optionally be used to constrain, for the given
client, the expected distinguished name of the root issuer of the
client certificate.
With the Public Key method of binding a certificate to a client, the
value "pub_key_tls_client_auth" is used for the
"token_endpoint_auth_method" client metadata parameter to indicate
the client's intention to use mutual TLS with a self-signed
certificate as an authentication method. For the Public Key method,
the existing "jwks_uri" or "jwks" metadata parameters from [RFC7591]
are used to convey client's public keys, where the X.509 certificates
are represented using the "x5c" parameter from [RFC7517].
3. Mutual TLS Sender Constrained Resources Access
When mutual TLS is used at the token endpoint, the authorization
server is able to bind the issued access token to the client
certificate. Such a binding is accomplished by associating the
certificate with the token in a way that can be accessed by the
protected resource, such as embedding the certificate hash in the
issued access token directly, using the syntax described in
Section 3.1, or through token introspection as described in
Section 3.2. Other methods of associating a certificate with an
access token are possible, per agreement by the authorization server
and the protected resource, but are beyond the scope of this
specification.
The client makes protected resource requests as described in
[RFC6750], however, those requests MUST be made over a mutually
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authenticated TLS connection using the same certificate that was used
for mutual TLS at the token endpoint.
The protected resource MUST obtain the client certificate used for
mutual TLS authentication and MUST verify that the certificate
matches the certificate associated with the access token. If they do
not match, the resource access attempt MUST be rejected with an error
per [RFC6750] using an HTTP 401 status code and the "invalid_token"
error code.
3.1. X.509 Certificate SHA-256 Thumbprint Confirmation Method for JWT
When access tokens are represented as a JSON Web Tokens
(JWT)[RFC7519], the certificate hash information SHOULD be
represented using the "x5t#S256" confirmation method member defined
herein.
To represent the hash of a certificate in a JWT, this specification
defines the new JWT Confirmation Method RFC 7800 [RFC7800] member
"x5t#S256" for the X.509 Certificate SHA-256 Thumbprint. The value
of the "x5t#S256" member is a base64url-encoded SHA-256[SHS] hash
(a.k.a. thumbprint or digest) of the DER encoding of the X.509
certificate[RFC5280] (note that certificate thumbprints are also
sometimes also known as certificate fingerprints).
The following is an example of a JWT payload containing an "x5t#S256"
certificate thumbprint confirmation method.
{
"iss": "https://server.example.com",
"sub": "ty.webb@example.com",
"exp": 1493726400,
"nbf": 1493722800,
"cnf":{
"x5t#S256": "bwcK0esc3ACC3DB2Y5_lESsXE8o9ltc05O89jdN-dg2"
}
}
Figure 1: Example claims of a Certificate Thumbprint Constrained JWT
If, in the future, certificate thumbprints need to be computed using
hash functions other than SHA-256, it is suggested that additional
related JWT confirmation methods members be defined for that purpose.
For example, a new "x5t#S512" (X.509 Certificate Thumbprint using
SHA-512) confirmation method member could be defined by registering
it in the the IANA "JWT Confirmation Methods" registry
[IANA.JWT.Claims] for JWT "cnf" member values established by
[RFC7800].
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3.2. Confirmation Method for Token Introspection
OAuth 2.0 Token Introspection [RFC7662] defines a method for a
protected resource to query an authorization server about the active
state of an access token as well as to determine meta-information
about the token.
For a mutual TLS sender constrained access token, the hash of the
certificate to which the token is bound is conveyed to the protected
resource as meta-information in a token introspection response. The
hash is conveyed using same structure as the certificate SHA-256
thumbprint confirmation method, described in Section 3.1, as a top-
level member of the introspection response JSON. The protected
resource compares that certificate hash to a hash of the client
certificate used for mutual TLS authentication and rejects the
request, if they do not match.
Proof-of-Possession Key Semantics for JSON Web Tokens [RFC7800]
defined the "cnf" (confirmation) claim, which enables confirmation
key information to be carried in a JWT. However, the same proof-of-
possession semantics are also useful for introspected access tokens
whereby the protected resource obtains the confirmation key data as
meta-information of a token introspection response and uses that
information in verifying proof-of-possession. Therefore this
specification defines and registers proof-of-possession semantics for
OAuth 2.0 Token Introspection [RFC7662] using the "cnf" structure.
When included as a top-level member of an OAuth token introspection
response, "cnf" has the same semantics and format as the claim of the
same name defined in [RFC7800]. While this specification only
explicitly uses the "x5t#S256" confirmation method member, it needed
to define and register the higher level "cnf" structure as an
introspection response member in order to define and use its more
specific "x5t#S256" confirmation method.
The following is an example of an introspection response for an
active token with an "x5t#S256" certificate thumbprint confirmation
method.
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HTTP/1.1 200 OK
Content-Type: application/json
{
"active": true,
"iss": "https://server.example.com",
"sub": "ty.webb@example.com",
"exp": 1493726400,
"nbf": 1493722800,
"cnf":{
"x5t#S256": "bwcK0esc3ACC3DB2Y5_lESsXE8o9ltc05O89jdN-dg2"
}
}
Figure 2: Example Introspection Response for a Certificate
Constrained Access Token
4. Implementation Considerations
4.1. Authorization Server
The authorization server needs to setup its TLS configuration
appropriately for the binding methods it supports.
If the authorization server wants to support mutual TLS client
authentication and other client authentication methods in parallel,
it should make mutual TLS optional on the token endpoint.
If the authorization server supports the Public Key method, it should
configure the TLS stack in a way that it does not verify whether the
certificate presented by the client during the handshake is signed by
a trusted CA certificate.
Please note: the Public Key method is intended to support client
authentication using self-signed certificates.
The authorization server may also consider hosting the token endpoint
on a separate host name in order to prevent unintended impact on the
TLS behavior of its other endpoints, e.g. authorization or
registration.
4.2. Resource Server
From the perspective of the resource server, TLS client
authentication is used as a proof of possession method only. For the
purpose of client authentication, the resource server may completely
rely on the authorization server. So there is no need to validate
the trust chain of the client's certificate in any of the methods
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defined in this document. The resource server should therefore
configure the TLS stack in a way that it does not verify whether the
certificate presented by the client during the handshake is signed by
a trusted CA certificate.
4.3. Sender Constrained Access Tokens Without Client Authentication
This document allows for the use of client authentication only or
client authentication in combination with sender constraint access
tokens. Use of mutual TLS sender constrained access tokens without
client authentication (e.g. to support binding access tokens to a TLS
client certificate for public clients) is also possible. The
authorization server would configure the TLS stack in the same manor
as for the Public Key method such that it does not verify that the
certificate presented by the client during the handshake is signed by
a trusted CA. Individual instances of a public client would then
create a self-signed certificate for mutual TLS with the
authorization server and resource server. The authorization server
would not authenticate the client at the OAuth layer but would bind
issued access tokens to the certificate, which the client has proven
possession of the corresponding private key. The access token is
then mutual TLS sender constrained and can only be used by the client
possessing the certificate and private key and utilizing them to
negotiate mutual TLS on connections to the resource server.
4.4. Certificate Bound Access Tokens
As described in Section 3, an access token is bound to a specific
client certificate, which means that the same certificate must be
used for mutual TLS on protected resource access. It also implies
that access tokens are invalidated when a client updates the
certificate, which can be handled similar to expired access tokens
where the client requests a new access token (typically with a
refresh token) and retries the protected resource request.
5. IANA Considerations
5.1. JWT Confirmation Methods Registration
This specification requests registration of the following value in
the IANA "JWT Confirmation Methods" registry [IANA.JWT.Claims] for
JWT "cnf" member values established by [RFC7800].
5.1.1. Registry Contents
o Confirmation Method Value: "x5t#S256"
o Confirmation Method Description: X.509 Certificate SHA-256
Thumbprint
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o Change Controller: IESG
o Specification Document(s): Section 3.1 of [[ this specification ]]
5.2. OAuth Authorization Server Metadata Registration
This specification requests registration of the following value in
the IANA "OAuth Authorization Server Metadata" registry
[IANA.OAuth.Parameters] established by [I-D.ietf-oauth-discovery].
5.2.1. Registry Contents
o Metadata Name: "mutual_tls_sender_constrained_access_tokens"
o Metadata Description: Indicates server support for mutual TLS
sender constraint access tokens.
o Change Controller: IESG
o Specification Document(s): Section 2.2 of [[ this specification ]]
5.3. Token Endpoint Authentication Method Registration
This specification requests registration of the following value in
the IANA "OAuth Token Endpoint Authentication Methods" registry
[IANA.OAuth.Parameters] established by [RFC7591].
5.3.1. Registry Contents
o Token Endpoint Authentication Method Name: "tls_client_auth"
o Change Controller: IESG
o Specification Document(s): Section 2.2 of [[ this specification ]]
o Token Endpoint Authentication Method Name:
"pub_key_tls_client_auth"
o Change Controller: IESG
o Specification Document(s): Section 2.2 of [[ this specification ]]
5.4. OAuth Token Introspection Response Registration
This specification requests registration of the following value in
the IANA "OAuth Token Introspection Response" registry
[IANA.OAuth.Parameters] established by [RFC7662].
5.4.1. Registry Contents
o Claim Name: "cnf"
o Claim Description: Confirmation
o Change Controller: IESG
o Specification Document(s): Section 3.2 of [[ this specification ]]
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5.5. OAuth Dynamic Client Registration Metadata Registration
This specification requests registration of the following client
metadata definitions in the IANA "OAuth Dynamic Client Registration
Metadata" registry [IANA.OAuth.Parameters] established by [RFC7591]:
5.5.1. Registry Contents
o Client Metadata Name:
"mutual_tls_sender_constrained_access_tokens"
o Client Metadata Description: Indicates the client's intention to
use mutual TLS sender constraint access tokens.
o Change Controller: IESG
o Specification Document(s): Section 2.3 of [[ this specification ]]
o Client Metadata Name: "tls_client_auth_subject_dn"
o Client Metadata Description: String value specifying the expected
subject distinguished name of the client certificate.
o Change Controller: IESG
o Specification Document(s): Section 2.3 of [[ this specification ]]
o Client Metadata Name: "tls_client_auth_root_dn"
o Client Metadata Description: String value specifying the expected
distinguished name of the root issuer of the client certificate
o Change Controller: IESG
o Specification Document(s): Section 2.3 of [[ this specification ]]
6. Security Considerations
6.1. TLS Versions and Best Practices
TLS 1.2 [RFC5246] is cited in this document because, at the time of
writing, it is latest version that is widely deployed. However, this
document is applicable with other TLS versions supporting
certificate-based client authentication. Implementation security
considerations for TLS, including version recommendations, can be
found in Recommendations for Secure Use of Transport Layer Security
(TLS) and Datagram Transport Layer Security (DTLS) [BCP195].
6.2. X.509 Certificate Spoofing
If the PKI method is used, an attacker could try to impersonate a
client using a certificate for the same DN issued by another CA,
which the authorization server trusts.
There are two ways to cope with that threat: the authorization server
may decide to only accept a limited number of CAs whose certificate
issuance policy meets its security requirements. Alternatively or in
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addition, the client may want to explicitly prescribe the CA it will
use for obtaining its certificates. The latter is supported by this
document with the client registration parameter
"tls_client_auth_root_dn".
7. References
7.1. Normative References
[BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <http://www.rfc-editor.org/info/bcp195>.
[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>.
[RFC4514] Zeilenga, K., Ed., "Lightweight Directory Access Protocol
(LDAP): String Representation of Distinguished Names",
RFC 4514, DOI 10.17487/RFC4514, June 2006,
<http://www.rfc-editor.org/info/rfc4514>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[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>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<http://www.rfc-editor.org/info/rfc6749>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012,
<http://www.rfc-editor.org/info/rfc6750>.
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[RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
Possession Key Semantics for JSON Web Tokens (JWTs)",
RFC 7800, DOI 10.17487/RFC7800, April 2016,
<http://www.rfc-editor.org/info/rfc7800>.
[SHS] National Institute of Standards and Technology, "Secure
Hash Standard (SHS)", FIPS PUB 180-4, March 2012,
<http://csrc.nist.gov/publications/fips/fips180-4/
fips-180-4.pdf>.
7.2. Informative References
[I-D.ietf-oauth-discovery]
Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
Authorization Server Metadata", draft-ietf-oauth-
discovery-04 (work in progress), August 2016.
[IANA.JWT.Claims]
IANA, "JSON Web Token Claims",
<http://www.iana.org/assignments/jwt>.
[IANA.OAuth.Parameters]
IANA, "OAuth Parameters",
<http://www.iana.org/assignments/oauth-parameters>.
[OpenID.Discovery]
Sakimura, N., Bradley, J., Jones, M., and E. Jay, "OpenID
Connect Discovery 1.0", February 2014.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<http://www.rfc-editor.org/info/rfc7517>.
[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>.
[RFC7591] Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
RFC 7591, DOI 10.17487/RFC7591, July 2015,
<http://www.rfc-editor.org/info/rfc7591>.
[RFC7662] Richer, J., Ed., "OAuth 2.0 Token Introspection",
RFC 7662, DOI 10.17487/RFC7662, October 2015,
<http://www.rfc-editor.org/info/rfc7662>.
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Appendix A. Acknowledgements
Scott "not Tomlinson" Tomilson and Matt Peterson were involved in
design and development work on a mutual TLS OAuth client
authentication implementation that informed some of the content of
this document.
Additionally, the authors would like to thank the following people
for their input and contributions to the specification: Sergey
Beryozkin, Vladimir Dzhuvinov, Samuel Erdtman, Phil Hunt, Sean
Leonard, Kepeng Li, James Manger, Jim Manico, Nov Matake, Sascha
Preibisch, Justin Richer, Dave Tonge, and Hannes Tschofenig.
Appendix B. Document(s) History
[[ to be removed by the RFC Editor before publication as an RFC ]]
draft-ietf-oauth-mtls-03
o Introduced metadata and client registration parameter to publish
and request support for mutual TLS sender constrained access
tokens
o Added description of two methods of binding the cert and client,
PKI and Public Key.
o Indicated that the "tls_client_auth" authentication method is for
the PKI method and introduced "pub_key_tls_client_auth" for the
Public Key method
o Added implementation considerations, mainly regarding TLS stack
configuration and trust chain validation, as well as how to to do
binding of access tokens to a TLS client certificate for public
clients, and considerations around certificate bound access tokens
o Added new section to security considerations on cert spoofing
o Add text suggesting that a new cnf member be defined in the
future, if hash function(s) other than SHA-256 need to be used for
certificate thumbprints
draft-ietf-oauth-mtls-02
o Fixed editorial issue https://mailarchive.ietf.org/arch/msg/oauth/
U46UMEh8XIOQnvXY9pHFq1MKPns
o Changed the title (hopefully "Mutual TLS Profile for OAuth 2.0" is
better than "Mutual TLS Profiles for OAuth Clients").
draft-ietf-oauth-mtls-01
o Added more explicit details of using RFC 7662 token introspection
with mutual TLS sender constrained access tokens.
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o Added an IANA OAuth Token Introspection Response Registration
request for "cnf".
o Specify that tls_client_auth_subject_dn and
tls_client_auth_root_dn are RFC 4514 String Representation of
Distinguished Names.
o Changed tls_client_auth_issuer_dn to tls_client_auth_root_dn.
o Changed the text in the Section 3 to not be specific about using a
hash of the cert.
o Changed the abbreviated title to 'OAuth Mutual TLS' (previously
was the acronym MTLSPOC).
draft-ietf-oauth-mtls-00
o Created the initial working group version from draft-campbell-
oauth-mtls
draft-campbell-oauth-mtls-01
o Fix some typos.
o Add to the acknowledgements list.
draft-campbell-oauth-mtls-00
o Add a Mutual TLS sender constrained protected resource access
method and a x5t#S256 cnf method for JWT access tokens (concepts
taken in part from draft-sakimura-oauth-jpop-04).
o Fixed "token_endpoint_auth_methods_supported" to
"token_endpoint_auth_method" for client metadata.
o Add "tls_client_auth_subject_dn" and "tls_client_auth_issuer_dn"
client metadata parameters and mention using "jwks_uri" or "jwks".
o Say that the authentication method is determined by client policy
regardless of whether the client was dynamically registered or
statically configured.
o Expand acknowledgements to those that participated in discussions
around draft-campbell-oauth-tls-client-auth-00
o Add Nat Sakimura and Torsten Lodderstedt to the author list.
draft-campbell-oauth-tls-client-auth-00
o Initial draft.
Authors' Addresses
Brian Campbell
Ping Identity
Email: brian.d.campbell@gmail.com
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John Bradley
Yubico
Email: ve7jtb@ve7jtb.com
URI: http://www.thread-safe.com/
Nat Sakimura
Nomura Research Institute
Email: n-sakimura@nri.co.jp
URI: https://nat.sakimura.org/
Torsten Lodderstedt
YES Europe AG
Email: torsten@lodderstedt.net
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