Internet-Draft | OAuth DPoP | May 2020 |
Fett, et al. | Expires 2 November 2020 | [Page] |
- Workgroup:
- Web Authorization Protocol
- Internet-Draft:
- draft-ietf-oauth-dpop-01
- Published:
- Intended Status:
- Standards Track
- Expires:
OAuth 2.0 Demonstration of Proof-of-Possession at the Application Layer (DPoP)
Abstract
This document describes a mechanism for sender-constraining OAuth 2.0 tokens via a proof-of-possession mechanism on the application level. This mechanism allows for the detection of replay attacks with access and refresh 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 working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 2 November 2020.¶
Copyright Notice
Copyright (c) 2020 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 Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.¶
1. Introduction
This document outlines a relatively simple application-level mechanism for
sender-constraining OAuth access and refresh tokens. It enables a client to
demonstrate proof-of-possession of a public/private key pair by including
the DPoP
header in an HTTP request. Using that header, an authorization
server is able to bind issued tokens to the public part of the client's
key pair. Recipients of such tokens are then able to verify the binding of the
token to the key pair that the client has demonstrated that it holds via
the DPoP
header, thereby providing some assurance that the client presenting
the token also possesses the private key.
In other words, the legitimate presenter of the token is constrained to be
the sender that holds and can prove possession of the private part of the
key pair.¶
The mechanism described herein can be used in cases where potentially stronger methods of sender-constraining tokens that utilize elements of the underlying secure transport layer, such as [RFC8705] or [I-D.ietf-oauth-token-binding], are not available or desirable. For example, due to a sub-par user experience of TLS client authentication in user agents and a lack of support for HTTP token binding, neither mechanism can be used if an OAuth client is a Single Page Application (SPA) running in a web browser.¶
DPoP can be used with public clients to sender-constrain access tokens and refresh tokens. With confidential clients, DPoP can be used in conjunction with any client authentication method to sender-constrain access tokens.¶
1.1. Conventions and 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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
This specification uses the terms "access token", "refresh token", "authorization server", "resource server", "authorization endpoint", "authorization request", "authorization response", "token endpoint", "grant type", "access token request", "access token response", and "client" defined by The OAuth 2.0 Authorization Framework [RFC6749].¶
2. Main Objective
Under the attacker model defined in [I-D.ietf-oauth-security-topics], the mechanism defined by this specification aims to prevent token replay at a different endpoint.¶
More precisely, if an adversary is able to get hold of an access token or refresh token because it set up a counterfeit authorization server or resource server, the adversary is not able to replay the respective token at another authorization or resource server.¶
3. Concept
The main data structure introduced by this specification is a DPoP proof JWT, described in detail below, sent as a header in an HTTP request. A client uses a DPoP proof JWT to prove the possession of a private key corresponding to a certain public key. Roughly speaking, a DPoP proof is a signature over a timestamp and some data of the HTTP request to which it is attached.¶
+--------+ +---------------+ | |--(A)-- Token Request ------------------->| | | Client | (DPoP Proof) | Authorization | | | | Server | | |<-(B)-- DPoP-bound Access Token ----------| | | | (token_type=DPoP) +---------------+ | | PoP Refresh Token for public clients | | | | +---------------+ | |--(C)-- DPoP-bound Access Token --------->| | | | (DPoP Proof) | Resource | | | | Server | | |<-(D)-- Protected Resource ---------------| | | | +---------------+ +--------+
The basic steps of an OAuth flow with DPoP are shown in Figure 1:¶
- (A) In the Token Request, the client sends an authorization code to the authorization server in order to obtain an access token (and potentially a refresh token). The client attaches a DPoP proof to the request in an HTTP header.¶
- (B) The AS binds (sender-constrains) the access token to the
public key claimed by the client in the DPoP proof; that is, the access token cannot
be used without proving possession of the respective private key.
This is signaled to the client by using the
token_type
valueDPoP
.¶ - If a refresh token is issued to a public client, it is
bound to the public key of the DPoP proof in a similar way.
Note that for confidential clients, refresh tokens are required by [RFC6749]
to bound to the
client_id
and associated authentication credentials, which is a sender-constraining mechanism that is more flexible than binding to a particular public key.¶ - (C) If the client wants to use the access token, it has to prove possession of the private key by, again, adding a header to the request that carries the DPoP proof. The resource server needs to receive information about the public key to which the access token is bound. This information is either encoded directly into the access token (for JWT structured access tokens), or provided at the token introspection endpoint of the authorization server (not shown). The resource server verifies that the public key to which the access token is bound matches the public key of the DPoP proof.¶
- (D) The resource server refuses to serve the request if the signature check fails or the data in the DPoP proof is wrong, e.g., the request URI does not match the URI claim in the DPoP proof JWT.¶
- When a refresh token that is sender-constrained using DPoP is used by the client, the client has to provide a DPoP proof just as in the case of a resource access. The new access token will be bound to the same public key.¶
The mechanism presented herein is not a client authentication method.
In fact, a primary use case of DPoP is for public clients (e.g., single page
applications) that do not use client authentication. Nonetheless, DPoP
is designed such that it is compatible with private_key_jwt
and all
other client authentication methods.¶
DPoP does not directly ensure message integrity but relies on the TLS layer for that purpose. See Section 9 for details.¶
4. DPoP Proof JWTs
DPoP introduces concept of a DPoP proof JWT, which is used for binding public
keys and proving knowledge about private keys. The DPoP proof JWT is sent with
an HTTP request using the DPoP
header field.¶
4.1. DPoP Proof JWT Syntax
A DPoP proof is a JWT ([RFC7519]) that is signed (using JWS, [RFC7515]) using a private key chosen by the client (see below). The header of a DPoP JWT contains at least the following parameters:¶
-
typ
: type header, valuedpop+jwt
(REQUIRED).¶ -
alg
: a digital signature algorithm identifier as per [RFC7518] (REQUIRED). MUST NOT benone
or an identifier for a symmetric algorithm (MAC).¶ -
jwk
: representing the public key chosen by the client, in JWK format, as defined in [RFC7515] (REQUIRED)¶
The body of a DPoP proof contains at least the following claims:¶
-
jti
: Unique identifier for the DPoP proof JWT (REQUIRED). The value MUST be assigned such that there is a negligible probability that the same value will be assigned to any other DPoP proof used in the same context during the time window of validity. Such uniqueness can be accomplished by encoding (base64url or any other suitable encoding) at least 96 bits of pseudorandom data or by using a version 4 UUID string according to [RFC4122]. Thejti
SHOULD be used by the server for replay detection and prevention, see Section 9.1.¶ -
htm
: The HTTP method for the request to which the JWT is attached, as defined in [RFC7231] (REQUIRED).¶ -
htu
: The HTTP URI used for the request, without query and fragment parts (REQUIRED).¶ -
iat
: Time at which the JWT was created (REQUIRED).¶
Figure 2 shows the JSON header and payload of a DPoP proof JWT.¶
{ "typ":"dpop+jwt", "alg":"ES256", "jwk": { "kty":"EC", "x":"l8tFrhx-34tV3hRICRDY9zCkDlpBhF42UQUfWVAWBFs", "y":"9VE4jf_Ok_o64zbTTlcuNJajHmt6v9TDVrU0CdvGRDA", "crv":"P-256" } }.{ "jti":"-BwC3ESc6acc2lTc", "htm":"POST", "htu":"https://server.example.com/token", "iat":1562262616 }
DPoP
proof header
Note: To keep DPoP simple to implement, only the HTTP method and URI are signed in DPoP proofs. The idea is sign just enough of the HTTP data to provide reasonable proof-of-possession with respect to the HTTP request. But that it be a minimal subset of the HTTP data so as to avoid the substantial difficulties inherent in attempting to normalize HTTP messages. Nonetheless, DPoP proofs can be extended to contain other information of the HTTP request (see also Section 9.4).¶
4.2. Checking DPoP Proofs
To check if a string that was received as part of an HTTP Request is a valid DPoP proof, the receiving server MUST ensure that¶
- the string value is a well-formed JWT,¶
- all required claims are contained in the JWT,¶
- the
typ
field in the header has the valuedpop+jwt
,¶ - the algorithm in the header of the JWT indicates an asymmetric digital
signature algorithm, is not
none
, is supported by the application, and is deemed secure,¶ - that the JWT is signed using the public key contained in the
jwk
header of the JWT,¶ - the
htm
claim matches the HTTP method value of the HTTP request in which the JWT was received (case-insensitive),¶ - the
htu
claims matches the HTTP URI value for the HTTP request in which the JWT was received, ignoring any query and fragment parts,¶ - the token was issued within an acceptable timeframe (see Section 9.1), and¶
- that, within a reasonable consideration of accuracy and resource utilization,
a JWT with the same
jti
value has not been received previously (see Section 9.1).¶
Servers SHOULD employ Syntax-Based Normalization and Scheme-Based
Normalization in accordance with Section 6.2.2. and Section 6.2.3. of
[RFC3986] before comparing the htu
claim.¶
5. Token Request (Binding Tokens to a Public Key)
To bind a token to a public key in the token request, the client MUST
provide a valid DPoP proof JWT in a DPoP
header. The HTTPS request shown
in Figure 3 illustrates the protocol for this (with extra line breaks
for display purposes only).¶
POST /token HTTP/1.1 Host: server.example.com Content-Type: application/x-www-form-urlencoded;charset=UTF-8 DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg 4PtFLbdLXiOSsX0x7NVY-FNyJK70nfbV37xRZT3Lg grant_type=authorization_code &code=SplxlOBeZQQYbYS6WxSbIA &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &code_verifier=bEaL42izcC-o-xBk0K2vuJ6U-y1p9r_wW2dFWIWgjz-
The DPoP
HTTP header MUST contain a valid DPoP proof JWT.
If the DPoP proof is invalid, the authorization server issues an error
response per Section 5.2 of [RFC6749] with invalid_dpop_proof
as the
value of the error
parameter.¶
The authorization server, after checking the validity of the DPoP proof,
associates the access token issued at the token endpoint with the
public key. It then sets token_type
to DPoP
in the token
response, which signals to the client that the access token was bound to
its DPoP key and can used as described in Section 6.¶
If a refresh token is issued to a public client at the token endpoint and a valid DPoP proof is presented, the refresh token MUST be bound to the public key contained in the header of the DPoP proof JWT.¶
When a DPoP-bound refresh token is used at the token endpoint by a public client, the AS MUST ensure that the DPoP proof contains the same public key as the one the refresh token is bound to. The access token issued MUST be bound to the public key contained in the DPoP proof.¶
6. Resource Access (Proof of Possession for Access Tokens)
To make use of an access token that is bound to a public key
using DPoP, a client MUST prove the possession of the corresponding
private key by providing a DPoP proof in the DPoP
request header.¶
A DPoP-bound access token is sent using the Authorization
request
header field per Section 2 of [RFC7235] using an
authentication scheme of DPoP
. The syntax of the Authorization
header field for the DPoP
scheme
uses the token68
syntax defined in Section 2.1 of [RFC7235]
(repeated below for ease of reference) for credentials.
The Augmented Backus-Naur Form (ABNF) notation [RFC5234] syntax
for DPoP Authorization scheme credentials is as follows:¶
token68 = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" ) *"=" credentials = "DPoP" 1*SP token68
For such an access token, a resource server
MUST check that a DPoP
header was received in the HTTP request,
check the header's contents according to the rules in Section 4.2,
and check that the public key of the DPoP proof matches the public
key to which the access token is bound per Section 7.¶
The resource server MUST NOT grant access to the resource unless all checks are successful.¶
GET /protectedresource HTTP/1.1 Host: resource.example.org Authorization: DPoP eyJhbGciOiJFUzI1NiIsImtpZCI6IkJlQUxrYiJ9.eyJzdWI iOiJzb21lb25lQGV4YW1wbGUuY29tIiwiaXNzIjoiaHR0cHM6Ly9zZXJ2ZXIuZXhhbX BsZS5jb20iLCJhdWQiOiJodHRwczovL3Jlc291cmNlLmV4YW1wbGUub3JnIiwibmJmI joxNTYyMjYyNjExLCJleHAiOjE1NjIyNjYyMTYsImNuZiI6eyJqa3QiOiIwWmNPQ09S Wk5ZeS1EV3BxcTMwalp5SkdIVE4wZDJIZ2xCVjN1aWd1QTRJIn19.vsFiVqHCyIkBYu 50c69bmPJsj8qYlsXfuC6nZcLl8YYRNOhqMuRXu6oSZHe2dGZY0ODNaGg1cg-kVigzY hF1MQ DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiJlMWozVl9iS2ljOC1MQUVCIiwiaHRtIj oiR0VUIiwiaHR1IjoiaHR0cHM6Ly9yZXNvdXJjZS5leGFtcGxlLm9yZy9wcm90ZWN0Z WRyZXNvdXJjZSIsImlhdCI6MTU2MjI2MjYxOH0.lNhmpAX1WwmpBvwhok4E74kWCiGB NdavjLAeevGy32H3dbF0Jbri69Nm2ukkwb-uyUI4AUg1JSskfWIyo4UCbQ
Upon receipt of a request for a URI of a protected resource within
the protection space requiring DPoP authorization, if the request does
not include valid credentials or or does not contain an access
token sufficient for access to the protected resource, the server
can reply with a challenge using the 401 (Unauthorized) status code
([RFC7235], Section 3.1) and the WWW-Authenticate
header field
([RFC7235], Section 4.1). The server MAY include the
WWW-Authenticate
header in response to other conditions as well.¶
In such challenges:¶
- The scheme name is
DPoP
.¶ - The authentication parameter
realm
MAY be included to indicate the scope of protection in the manner described in [RFC7235], Section 2.2.¶ - A
scope
authentication parameter MAY be included as defined in [RFC6750], Section 3.¶ - An
error
parameter ([RFC6750], Section 3) SHOULD be included to indicate the reason why the request was declined, if the request included an access token but failed authorization. Parameter values are described in Section 3.1 of [RFC6750].¶ - An
error_description
parameter ([RFC6750], Section 3) MAY be included along with theerror
parameter to provide developers a human-readable explanation that is not meant to be displayed to end-users.¶ - An
algs
parameter SHOULD be included to signal to the client the JWS algorithms that are acceptable for the DPoP proof JWT. The value of the parameter is a space-delimited list of JWSalg
(Algorithm) header values ([RFC7515], Section 4.1.1).¶ - Additional authentication parameters MAY be used and unknown parameters MUST be ignored by recipients¶
For example, in response to a protected resource request without authentication:¶
HTTP/1.1 401 Unauthorized WWW-Authenticate: DPoP realm="WallyWorld", algs="ES256 PS256"
And in response to a protected resource request that was rejected because the confirmation of the DPoP binding in the access token failed:¶
HTTP/1.1 401 Unauthorized WWW-Authenticate: DPoP realm="WallyWorld", error="invalid_token", error_description="Invalid DPoP key binding", algs="ES256"
7. Public Key Confirmation
It MUST be ensured that resource servers can reliably identify whether a token is bound using DPoP and learn the public key to which the token is bound.¶
Access tokens that are represented as JSON Web Tokens (JWT) [RFC7519]
MUST contain information about the DPoP public key (in JWK format) in
the member jkt
of the cnf
claim, as shown in Figure 8.¶
The value in jkt
MUST be the base64url encoding [RFC7515] of
the JWK SHA-256 Thumbprint (according to [RFC7638]) of the public
key to which the access token is bound.¶
{ "sub":"someone@example.com", "iss":"https://server.example.com", "aud":"https://resource.example.org", "nbf":1562262611, "exp":1562266216, "cnf":{ "jkt":"0ZcOCORZNYy-DWpqq30jZyJGHTN0d2HglBV3uiguA4I" } }
cnf
claim
When access token introspection is used, the same cnf
claim as above
MUST be contained in the introspection response.¶
Resource servers MUST ensure that the fingerprint of the public key in
the DPoP proof JWT equals the value in the jkt
claim in the access
token or introspection response.¶
8. Authorization Server Metadata
This document introduces the following new authorization server metadata
[RFC8414] parameter to signal the JWS alg
values the authorization server
supports for DPoP proof JWTs:¶
dpop_signing_alg_values_supported
- OPTIONAL. JSON array containing a list of the JWS
alg
values supported by the authorization server for DPoP proof JWTs¶
9. Security Considerations
In DPoP, the prevention of token replay at a different endpoint (see Section 2) is achieved through the binding of the DPoP proof to a certain URI and HTTP method. DPoP does not, however, achieve the same level of protection as TLS-based methods such as OAuth Mutual TLS [RFC8705] or OAuth Token Binding [I-D.ietf-oauth-token-binding] (see also Section 9.1 and Section 9.4). TLS-based mechanisms can leverage a tight integration between the TLS layer and the application layer to achieve a very high level of message integrity and replay protection. Therefore, it is RECOMMENDED to prefer TLS-based methods over DPoP if such methods are suitable for the scenario at hand.¶
9.1. DPoP Proof Replay
If an adversary is able to get hold of a DPoP proof JWT, the adversary
could replay that token at the same endpoint (the HTTP endpoint
and method are enforced via the respective claims in the JWTs). To
prevent this, servers MUST only accept DPoP proofs for a limited time
window after their iat
time, preferably only for a relatively brief period.
Servers SHOULD store the jti
value of each DPoP proof for the time window in
which the respective DPoP proof JWT would be accepted and decline HTTP requests
for which the jti
value has been seen before. In order to guard against
memory exhaustion attacks a server SHOULD reject DPoP proof JWTs with unnecessarily
large jti
values or store only a hash thereof.¶
Note: To accommodate for clock offsets, the server MAY accept DPoP
proofs that carry an iat
time in the near future (e.g., up to a few
seconds in the future).¶
9.2. Signed JWT Swapping
Servers accepting signed DPoP proof JWTs MUST check the typ
field in the
headers of the JWTs to ensure that adversaries cannot use JWTs created
for other purposes.¶
9.3. Signature Algorithms
Implementers MUST ensure that only asymmetric digital signature algorithms that
are deemed secure can be used for signing DPoP proofs. In particular,
the algorithm none
MUST NOT be allowed.¶
9.4. Message Integrity
DPoP does not ensure the integrity of the payload or headers of requests. The signature of DPoP proofs only contains the HTTP URI and method, but not, for example, the message body or other request headers.¶
This is an intentional design decision to keep DPoP simple to use, but as described, makes DPoP potentially susceptible to replay attacks where an attacker is able to modify message contents and headers. In many setups, the message integrity and confidentiality provided by TLS is sufficient to provide a good level of protection.¶
Implementers that have stronger requirements on the integrity of messages are encouraged to either use TLS-based mechanisms or signed requests. TLS-based mechanisms are in particular OAuth Mutual TLS [RFC8705] and OAuth Token Binding [I-D.ietf-oauth-token-binding].¶
Note: While signatures on (parts of) requests are out of the scope of this specification, signatures or information to be signed can be added into DPoP proofs.¶
10. IANA Considerations
10.1. OAuth Access Token Type Registration
This specification requests registration of the following access token type in the "OAuth Access Token Types" registry [IANA.OAuth.Params] established by [RFC6749].¶
10.2. HTTP Authentication Scheme Registration
This specification requests registration of the following scheme in the "Hypertext Transfer Protocol (HTTP) Authentication Scheme Registry" [RFC7235][IANA.HTTP.AuthSchemes]:¶
10.3. Media Type Registration
[[
Is a media type registration at [IANA.MediaTypes] necessary for application/dpop+jwt
?
There is a +jwt
structured syntax suffix registered already at [IANA.MediaType.StructuredSuffixs]
by Section 7.2 of [RFC8417], which is maybe sufficient? A fullblown registration
of application/dpop+jwt
seems like it'd be overkill.
The dpop+jwt
is used in the JWS/JWT typ
header for explicit typing of the JWT per
Section 3.11 of [RFC8725] but it is not used anywhere else (such as the Content-Type
of HTTP messages).¶
Note that there does seem to be some precedence for [IANA.MediaTypes] registration with [I-D.ietf-oauth-access-token-jwt], [I-D.ietf-oauth-jwsreq], [RFC8417], and of course [RFC7519]. But precedence isn't always right. ]]¶
10.4. JWT Confirmation Methods Registration
This specification requests registration of the following value
in the IANA "JWT Confirmation Methods" registry [IANA.JWT]
for JWT cnf
member values established by [RFC7800].¶
10.5. JSON Web Token Claims Registration
This specification requests registration of the following Claims in the IANA "JSON Web Token Claims" registry [IANA.JWT] established by [RFC7519].¶
HTTP method:¶
- Claim Name:
htm
¶ - Claim Description: The HTTP method of the request¶
- Change Controller: IESG¶
- Specification Document(s): [[ Section 4.1 of this specification ]]¶
HTTP URI:¶
- Claim Name:
htu
¶ - Claim Description: The HTTP URI of the request (without query and fragment parts)¶
- Change Controller: IESG¶
- Specification Document(s): [[ Section 4.1 of this specification ]]¶
10.6. HTTP Message Header Field Names Registration
This document specifies the following new HTTP header fields, registration of which is requested in the "Permanent Message Header Field Names" registry [IANA.Headers] defined in [RFC3864].¶
11. Normative References
- [RFC7800]
- Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)", RFC 7800, DOI 10.17487/RFC7800, , <https://www.rfc-editor.org/info/rfc7800>.
- [RFC6749]
- Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, , <https://www.rfc-editor.org/info/rfc6749>.
- [RFC5234]
- Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, , <https://www.rfc-editor.org/info/rfc5234>.
- [RFC3986]
- Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, , <https://www.rfc-editor.org/info/rfc3986>.
- [RFC6750]
- Jones, M. and D. Hardt, "The OAuth 2.0 Authorization Framework: Bearer Token Usage", RFC 6750, DOI 10.17487/RFC6750, , <https://www.rfc-editor.org/info/rfc6750>.
- [RFC7518]
- Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, DOI 10.17487/RFC7518, , <https://www.rfc-editor.org/info/rfc7518>.
- [RFC7638]
- Jones, M. and N. Sakimura, "JSON Web Key (JWK) Thumbprint", RFC 7638, DOI 10.17487/RFC7638, , <https://www.rfc-editor.org/info/rfc7638>.
- [RFC7231]
- Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, , <https://www.rfc-editor.org/info/rfc7231>.
- [RFC7515]
- Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, , <https://www.rfc-editor.org/info/rfc7515>.
12. Informative References
- [I-D.ietf-oauth-token-binding]
- Jones, M., Campbell, B., Bradley, J., and W. Denniss, "OAuth 2.0 Token Binding", Work in Progress, Internet-Draft, draft-ietf-oauth-token-binding-08, , <https://tools.ietf.org/html/draft-ietf-oauth-token-binding-08>.
- [I-D.ietf-oauth-access-token-jwt]
- Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0 Access Tokens", Work in Progress, Internet-Draft, draft-ietf-oauth-access-token-jwt-07, , <https://tools.ietf.org/html/draft-ietf-oauth-access-token-jwt-07>.
- [I-D.ietf-oauth-jwsreq]
- Sakimura, N. and J. Bradley, "The OAuth 2.0 Authorization Framework: JWT Secured Authorization Request (JAR)", Work in Progress, Internet-Draft, draft-ietf-oauth-jwsreq-21, , <https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-21>.
- [RFC8705]
- Campbell, B., Bradley, J., Sakimura, N., and T. Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication and Certificate-Bound Access Tokens", RFC 8705, DOI 10.17487/RFC8705, , <https://www.rfc-editor.org/info/rfc8705>.
- [RFC8174]
- Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
- [IANA.MediaTypes]
- IANA, "Media Types", , <https://www.iana.org/assignments/media-types>.
- [RFC8414]
- Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0 Authorization Server Metadata", RFC 8414, DOI 10.17487/RFC8414, , <https://www.rfc-editor.org/info/rfc8414>.
- [RFC8417]
- Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, "Security Event Token (SET)", RFC 8417, DOI 10.17487/RFC8417, , <https://www.rfc-editor.org/info/rfc8417>.
- [IANA.JWT]
- IANA, "JSON Web Token Claims", , <http://www.iana.org/assignments/jwt>.
- [RFC3864]
- Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, DOI 10.17487/RFC3864, , <https://www.rfc-editor.org/info/rfc3864>.
- [RFC2119]
- Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
- [RFC7519]
- Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, , <https://www.rfc-editor.org/info/rfc7519>.
- [IANA.OAuth.Params]
- IANA, "OAuth Parameters", , <https://www.iana.org/assignments/oauth-parameters>.
- [IANA.MediaType.StructuredSuffixs]
- IANA, "Structured Syntax Suffix Registry", , <https://www.iana.org/assignments/media-type-structured-suffixs>.
- [IANA.Headers]
- IANA, "Message Headers", , <https://www.iana.org/assignments/message-headers>.
- [RFC7235]
- Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Authentication", RFC 7235, DOI 10.17487/RFC7235, , <https://www.rfc-editor.org/info/rfc7235>.
- [IANA.HTTP.AuthSchemes]
- IANA, "Hypertext Transfer Protocol (HTTP) Authentication Scheme Registry", , <https://www.iana.org/assignments/http-authschemes>.
- [RFC8725]
- Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best Current Practices", BCP 225, RFC 8725, DOI 10.17487/RFC8725, , <https://www.rfc-editor.org/info/rfc8725>.
- [I-D.ietf-oauth-security-topics]
- Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett, "OAuth 2.0 Security Best Current Practice", Work in Progress, Internet-Draft, draft-ietf-oauth-security-topics-15, , <https://tools.ietf.org/html/draft-ietf-oauth-security-topics-15>.
- [RFC4122]
- Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, DOI 10.17487/RFC4122, , <https://www.rfc-editor.org/info/rfc4122>.
Appendix A. Acknowledgements
We would like to thank Filip Skokan, Mike Engan, Justin Richer, Michael Peck, Vladimir Dzhuvinov, Rob Otto, Dominick Baier, Jim Willeke, Annabelle Backman, Bjorn Hjelm, Steinar Noem, Aaron Parecki, Neil Madden, Paul Querna, Dick Hardt, Dave Tonge, Jared Jennings, Mark Haine and others (please let us know, if you've been mistakenly omitted) for their valuable input, feedback and general support of this work.¶
This document resulted from discussions at the 4th OAuth Security Workshop in Stuttgart, Germany. We thank the organizers of this workshop (Ralf Kusters, Guido Schmitz).¶
Appendix B. Document History
[[ To be removed from the final specification ]]¶
-01¶
- Editorial updates¶
- Attempt to more formally define the DPoP Authorization header scheme¶
- Define the 401/WWW-Authenticate challenge¶
- Added
invalid_dpop_proof
error code for DPoP errors in token request¶ - Fixed up and added to the IANA section¶
- Added
dpop_signing_alg_values_supported
authorization server metadata¶ - Moved the Acknowledgements into an Appendix and added a bunch of names (best effort)¶
-00 [[ Working Group Draft ]]¶
- Working group draft¶
-04¶
-03¶
- rework the text around uniqueness requirements on the jti claim in the DPoP proof JWT¶
- make tokens a bit smaller by using
htm
,htu
, andjkt
rather thanhttp_method
,http_uri
, andjkt#S256
respectively¶ - more explicit recommendation to use mTLS if that is available¶
- added David Waite as co-author¶
- editorial updates¶
-02¶
- added normalization rules for URIs¶
- removed distinction between proof and binding¶
- "jwk" header again used instead of "cnf" claim in DPoP proof¶
- renamed "Bearer-DPoP" token type to "DPoP"¶
- removed ability for key rotation¶
- added security considerations on request integrity¶
- explicit advice on extending DPoP proofs to sign other parts of the HTTP messages¶
- only use the jkt#S256 in ATs¶
- iat instead of exp in DPoP proof JWTs¶
- updated guidance on token_type evaluation¶
-01¶
- fixed inconsistencies¶
- moved binding and proof messages to headers instead of parameters¶
- extracted and unified definition of DPoP JWTs¶
- improved description¶
-00¶
- first draft¶