|Internet-Draft||OAuth DPoP||November 2020|
|Fett, et al.||Expires 22 May 2021||[Page]|
- Web Authorization Protocol
- Intended Status:
- Standards Track
OAuth 2.0 Demonstrating Proof-of-Possession at the Application Layer (DPoP)
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 22 May 2021.¶
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.¶
DPoP, an abbreviation for Demonstrating Proof-of-Possession at the Application Layer,
is an 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
DPoP header in an HTTP request. The value of the header is a JWT [RFC7519] that
enables the authorization
server 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
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
The mechanism described herein can be used in cases where other 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. Native applications installed and run on a user's device, which often have dedicated protected storage for cryptographic keys. are another example well positioned to benefit from DPoP-bound tokens to guard against misuse of tokens by a compromised or malicious resource.¶
DPoP can be used to sender-constrain access tokens regardless of the
client authentication method employed. Furthermore, DPoP can
also be used to sender-constrain refresh tokens issued to public clients
(those without authentication credentials associated with the
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].¶
The primary aim of DPoP is to prevent unauthorized or illegitimate parties from using leaked or stolen access tokens by binding a token to a public key upon issuance and requiring that the client demonstrate possession of the corresponding private key when using the token. This constrains the legitimate sender of the token to only the party with access to the private key and gives the server receiving the token added assurances that the sender is legitimately authorized to use it.¶
Access tokens that are sender-constrained via DPoP thus stand in contrast to the typical bearer token, which can be used by any party in possession of such a token. Although protections generally exist to prevent unintended disclosure of bearer tokens, unforeseen vectors for leakage have occurred due to vulnerabilities and implementation issues in other layers in the protocol or software stack (CRIME, BREACH, Heartbleed, and the Cloudflare parser bug are some examples). There have also been numerous published token theft attacks on OAuth implementations themselves. DPoP provides a general defense in depth against the impact of unanticipated token leakage. DPoP is not, however, a substitute for a secure transport and MUST always be used in conjunction with HTTPS.¶
The very nature of the typical OAuth protocol interaction necessitates that the client disclose the access token to the protected resources that it accesses. The attacker model in [I-D.ietf-oauth-security-topics] describes cases where a protected resource might be counterfeit, malicious or compromised and play received tokens against other protected resources to gain unauthorized access. Properly audience restricting access tokens can prevent such misuse, however, doing so in practice has proven to be prohibitively cumbersome (even despite extensions such as [RFC8707]) for many deployments. Sender-constraining access tokens is a more robust and straightforward mechanism to prevent such token replay at a different endpoint and DPoP is an accessible application layer means of doing so.¶
Due to the potential for cross-site scripting (XSS), browser-based OAuth clients bring to bear added considerations with respect to protecting tokens. The most straightforward XSS-based attack is for an attacker to exfiltrate a token and use it themselves completely independent from the legitimate client. A stolen access token is used for protected resource access and a stolen refresh token for obtaining new access tokens. If the private key is non-extractable (as is possible with [W3C.WebCryptoAPI]), DPoP renders exfiltrated tokens alone unusable.¶
XXS vulnerabilities also allow an attacker to execute code in the context of the browser-based client application and maliciously use a token indirectly through the the client. That execution context has access to utilize the signing key and thus can produce DPoP proofs to use in conjunction with the token. At this application layer there is most likely no feasible defense against this threat except generally preventing XSS, therefore it is considered out of scope for DPoP.¶
Malicious XSS code executed in the context of the browser-based client application is also in a position to create DPoP proofs with timestamp values in the future and exfiltrate them in conjunction with a token. These stolen artifacts can later be used together independent of the client application to access protected resources. The impact of such precomputed DPoP proofs can be limited somewhat by a browser-based client generating and using a new DPoP key for each new authorization code grant.¶
Additional security considerations are discussed in Section 8.¶
The main data structure introduced by this specification is a DPoP proof JWT, described in detail below, which is 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.¶
The basic steps of an OAuth flow with DPoP are shown in Figure 1:¶
- (A) In the Token Request, the client sends an authorization grant
(e.g., an authorization code, refresh token, etc.)
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 authorization server 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. If a refresh token is issued to a public client, it too is bound to the public key of the DPoP proof.¶
- (C) To use the access token the client 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 may be encoded directly into the access token (for JWT structured access tokens) or provided via token introspection endpoint (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. The access token itself, of course, must also be valid in all other respects.¶
The DPoP 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 and native 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 8 for details.¶
4. DPoP Proof JWTs
DPoP introduces the concept of a DPoP proof, which is a JWT created by
the client and sent with an HTTP request using the
DPoP header field.
A valid DPoP proof demonstrates to the server that the client holds the private
key that was used to sign the JWT. This enables authorization servers to bind
issued tokens to the corresponding public key (as described in Section 5)
and for resource servers to verify the key-binding of tokens that
it receives (see Section 7.1), which prevents said tokens from
being used by any entity that does not have access to the private key.¶
The DPoP proof demonstrates possession of a key and, by itself, is not an authentication or access control mechanism. When presented in conjunction with a key-bound access token as described in Section 7.1, the DPoP proof provides additional assurance about the legitimacy of the client to present the access token. But a valid DPoP proof JWT is not sufficient alone to make access control decisions.¶
4.1. The DPoP HTTP Header
A DPoP proof is included in an HTTP request using the following message header field.¶
- A JWT that adheres to the structure and syntax of Section 4.2.¶
Figure 2 shows an example DPoP HTTP header field (line breaks and extra whitespace for display purposes only).¶
Note that per [RFC7230] header field names are case-insensitive;
dpop, etc., are all valid and equivalent header
field names. Case is significant in the header field value, however.¶
4.2. DPoP Proof JWT Syntax
A DPoP proof is a JWT ([RFC7519]) that is signed (using JWS, [RFC7515]) with a private key chosen by the client (see below). The header of a DPoP JWT contains at least the following parameters:¶
typ: type header, value
alg: a digital signature algorithm identifier as per [RFC7518] (REQUIRED). MUST NOT be
noneor 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]. The
jtican be used by the server for replay detection and prevention, see Section 8.1.¶
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 3 is a conceptual example showing the decoded content of the DPoP proof in Figure 2. The JSON of the JOSE header and payload are shown but the signature part is omitted. As usual, line breaks and extra whitespace are included for formatting and readability.¶
Of the HTTP content in the request, only the HTTP method and URI are included in the DPoP JWT, and therefore only these 2 headers of the request are covered by the DPoP proof and its signature. 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 8.4).¶
4.3. 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,¶
typfield in the header has the value
- 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
jwkheader of the JWT,¶
htmclaim matches the HTTP method value of the HTTP request in which the JWT was received,¶
htuclaims matches the HTTPS 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 8.1), and¶
- that, within a reasonable consideration of accuracy and resource utilization,
a JWT with the same
jtivalue has not previously been received at the same URI (see Section 8.1).¶
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
5. DPoP Access Token Request
To request an access token that is bound to a public key using DPoP, the client MUST
provide a valid DPoP proof JWT in a
DPoP header when making an access token
request to the authorization server's token endpoint. This is applicable for all
access token requests regardless of grant type (including, for example,
refresh_token grant types but also extension grants
such as the JWT authorization grant [RFC7523]). The HTTPS request shown in
Figure 4 illustrates an such an access
token request using an an authorization code grant with a DPoP proof JWT
DPoP header (extra line breaks and whitespace for display purposes only).¶
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
To sender-constrain the access token, after checking the validity of the
DPoP proof, the authorization server associates the issued access token with the
public key from the DPoP proof, which can be accomplished as described in Section 6.
DPoP in the access token
response signals to the client that the access token was bound to
its DPoP key and can used as described in Section 7.1.
The example response shown in Figure 5 illustrates such a
The example response in Figure 5 included a refresh token, which the
client can use to obtain a new access token when the the previous one expires.
Refreshing an access token is a token request using the
grant type made to the the authorization server's token endpoint. As with
all access token requests, the client makes it a DPoP request by including
a DPoP proof, which is shown in the Figure 6 example
(extra line breaks and whitespace for display purposes only).¶
When an authorization server supporting DPoP issues a refresh token to a public client that presents a valid DPoP proof at the token endpoint, the refresh token MUST be bound to the respective public key. The binding MUST be validated when the refresh token is later presented to get new access tokens. As a result, such a client MUST present a DPoP proof for the same key that was used to obtain the refresh token each time that refresh token is used to obtain a new access token. The implementation details of the binding of the refresh token are at the discretion of the authorization server. The server both produces and validates the refresh tokens that it issues so there's no interoperability consideration in the specific details of the binding.¶
An authorization server MAY elect to issue access tokens which are not DPoP bound,
which is signaled to the client with a value of
Bearer in the
of the access token response per [RFC6750]. For a public client that is
also issued a refresh token, this has the effect of DPoP-binding the refresh token
alone, which can improve the security posture even when protected resources are not
updated to support DPoP.¶
Refresh tokens issued to confidential clients (those having established authentication credentials with the authorization server) are not bound to the DPoP proof public key because they are already sender-constrained with a different existing mechanism. The OAuth 2.0 Authorization Framework [RFC6749] already requires that an authorization server bind refresh tokens to the client to which they were issued and that confidential clients authenticate to the authorization server when presenting a refresh token. As a result, such refresh tokens are sender-constrained by way of the client ID and the associated authentication requirement. This existing sender-constraining mechanism is more flexible (e.g., it allows credential rotation for the client without invalidating refresh tokens) than binding directly to a particular public key.¶
5.1. Authorization Server Metadata
This document introduces the following new authorization server metadata
[RFC8414] parameter to signal support for DPoP in general and the specific
alg values the authorization server supports for DPoP proof JWTs.¶
- A JSON array containing a list of the JWS
algvalues supported by the authorization server for DPoP proof JWTs.¶
6. Public Key Confirmation
Resource servers MUST be able to reliably identify whether an access token is bound using DPoP and ascertain sufficient information about the public key to which the token is bound in order to verify the binding with respect to the the presented DPoP proof (see Section 7.1). Such a binding is accomplished by associating the public key with the token in a way that can be accessed by the protected resource, such as embedding the JWK hash in the issued access token directly, using the syntax described in Section 6.1, or through token introspection as described in Section 6.2. Other methods of associating a public key with an access token are possible, per agreement by the authorization server and the protected resource, but are beyond the scope of this specification.¶
Resource servers supporting DPoP MUST ensure that the the public key from the DPoP proof matches the pubic key to which the access token is bound.¶
6.1. JWK Thumbprint Confirmation Method
When access tokens are represented as JSON Web Tokens (JWT) [RFC7519],
the public key information SHOULD be represented
jkt confirmation method member defined herein.
To convey the hash of a public key in a JWT, this specification
introduces the following new JWT Confirmation Method [RFC7800] member for
use under the
- JWK SHA-256 Thumbprint Confirmation Method. The value of the
jktmember MUST be the base64url encoding (as defined in [RFC7515]) of the JWK SHA-256 Thumbprint (according to [RFC7638]) of the DPoP public key (in JWK format) to which the access token is bound.¶
The following example JWT in Figure 7 with decoded JWT payload shown in
Figure 8 contains a
cnf claim with the
jkt JWK thumbprint confirmation
method member. The
jkt value in these examples is the hash of the public key
from the DPoP proofs in the examples in Section 5.¶
6.2. JWK Thumbprint Confirmation Method in 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 metainformation about the token.¶
For a DPoP-bound access token, the hash of the public key to which the token
is bound is conveyed to the protected resource as metainformation in a token
introspection response. The hash is conveyed using the same
cnf content with
jkt member structure as the JWK thumbprint confirmation method, described in
Section 6.1, as a top-level member of the
introspection response JSON. Note that the resource server
does not send a DPoP proof with the introspection request and the authorization
server does not validate an access token's DPoP binding at the introspection
endpoint. Rather the resource server uses the data of the introspection response
to validate the access token binding itself locally.¶
The example introspection request in Figure 9 and corresponding response in Figure 10 illustrate an introspection exchange for the example DPoP-bound access token that was issued in Figure 5.¶
7. Protected Resource Access
To make use of an access token that is bound to a public key
using DPoP, a client MUST prove possession of the corresponding
private key by providing a DPoP proof in the
DPoP request header.
As such, protected resource requests with a DPoP-bound access token
necessarily must include both a DPoP proof as per Section 4 and
the access token as described in Section 7.1.¶
7.1. The DPoP Authorization Request Header Scheme
A DPoP-bound access token is sent using the
header field per Section 2 of [RFC7235] using an
authentication scheme of
DPoP. The syntax of the
header field for 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:¶
For such an access token, a resource server MUST check that a DPoP proof
was also received in the
DPoP header field of the HTTP request,
check the DPoP proof according to the rules in Section 4.3,
and check that the public key of the DPoP proof matches the public
key to which the access token is bound per Section 6.¶
The resource server MUST NOT grant access to the resource unless all checks are successful.¶
Figure 12 shows an example request to a protected
resource with a DPoP-bound access token in the
and the DPoP proof in the
DPoP header (line breaks and extra
whitespace for display purposes only).¶
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 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
- The authentication parameter
realmMAY be included to indicate the scope of protection in the manner described in [RFC7235], Section 2.2.¶
scopeauthentication parameter MAY be included as defined in [RFC6750], Section 3.¶
errorparameter ([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].¶
error_descriptionparameter ([RFC6750], Section 3) MAY be included along with the
errorparameter to provide developers a human-readable explanation that is not meant to be displayed to end-users.¶
algsparameter 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 JWS
alg(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:¶
And in response to a protected resource request that was rejected because the confirmation of the DPoP binding in the access token failed:¶
8. 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, however, has a somewhat different nature of protection than TLS-based methods such as OAuth Mutual TLS [RFC8705] or OAuth Token Binding [I-D.ietf-oauth-token-binding] (see also Section 8.1 and Section 8.4). 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 with respect to the transport layer to which the token is bound and replay protection in general.¶
8.1. 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, in the context of the request URI, 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 to the same URI
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
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 reasonably near future (e.g., a few
seconds in the future).¶
8.2. 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.¶
8.3. Signature Algorithms
Implementers MUST ensure that only asymmetric digital signature algorithms that
are deemed secure can be used for signing DPoP proofs. In particular,
none MUST NOT be allowed.¶
8.4. Message Integrity
DPoP does not ensure the integrity of the payload or headers of requests. The DPoP proof only contains claims for the HTTP URI and method, but not, for example, the message body or general request headers.¶
This is an intentional design decision intended 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 covering other parts of requests are out of the scope of this specification, additional information to be signed can be added into DPoP proofs.¶
8.5. Public Key Binding
The binding between the DPoP public key and the access token, which is specified in Section 6, uses a cryptographic hash of the JWK representation of the public key. It relies on the hash function having sufficient second-preimage resistance so as to make it computationally infeasible to find or create another key that produces to the same hash output value. The SHA-256 hash function was used because it meets the aforementioned requirement while being widely available. If, in the future, JWK thumbprints need to be computed using hash function(s) other than SHA-256, it is suggested that, for additional related JWT confirmation methods, members be defined for that purpose and registered in the IANA "JWT Confirmation Methods" registry [IANA.JWT.Claims] for JWT "cnf" member values.¶
9. IANA Considerations
9.1. 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].¶
9.2. 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]:¶
- Authentication Scheme Name:
- Reference: [[ Section 7.1 of this specification ]]¶
9.3. Media Type Registration
Is a media type registration at [IANA.MediaTypes] necessary for
There is a
+jwt structured syntax suffix registered already at [IANA.MediaType.StructuredSuffix]
by Section 7.2 of [RFC8417], which is maybe sufficient? A full-blown registration
application/dpop+jwt seems like it'd be overkill.
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. ]]¶
9.4. JWT Confirmation Methods Registration
This specification requests registration of the following value
in the IANA "JWT Confirmation Methods" registry [IANA.JWT]
cnf member values established by [RFC7800].¶
9.5. 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].¶
- Claim Name:
- Claim Description: The HTTP method of the request¶
- Change Controller: IESG¶
- Specification Document(s): [[ Section 4.2 of this specification ]]¶
- Claim Name:
- Claim Description: The HTTP URI of the request (without query and fragment parts)¶
- Change Controller: IESG¶
- Specification Document(s): [[ Section 4.2 of this specification ]]¶
9.6. 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].¶
10. Normative References
- Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, , <https://www.rfc-editor.org/info/rfc7515>.
- Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, DOI 10.17487/RFC7518, , <https://www.rfc-editor.org/info/rfc7518>.
- Jones, M. and N. Sakimura, "JSON Web Key (JWK) Thumbprint", RFC 7638, DOI 10.17487/RFC7638, , <https://www.rfc-editor.org/info/rfc7638>.
- 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>.
- Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, , <https://www.rfc-editor.org/info/rfc6749>.
- 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>.
- 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>.
- 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>.
11. Informative References
- 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-16, , <https://tools.ietf.org/html/draft-ietf-oauth-security-topics-16>.
- Richer, J., Ed., "OAuth 2.0 Token Introspection", RFC 7662, DOI 10.17487/RFC7662, , <https://www.rfc-editor.org/info/rfc7662>.
- IANA, "OAuth Parameters", <https://www.iana.org/assignments/oauth-parameters>.
- 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>.
- 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>.
- 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>.
- Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0 Access Tokens", Work in Progress, Internet-Draft, draft-ietf-oauth-access-token-jwt-10, , <https://tools.ietf.org/html/draft-ietf-oauth-access-token-jwt-10>.
- IANA, "Message Headers", <https://www.iana.org/assignments/message-headers>.
- Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, , <https://www.rfc-editor.org/info/rfc7519>.
- 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>.
- Watson, M., "Web Cryptography API", , <https://www.w3.org/TR/2017/REC-WebCryptoAPI-20170126>.
- Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, , <https://www.rfc-editor.org/info/rfc7230>.
- 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>.
- 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>.
- Campbell, B., Bradley, J., and H. Tschofenig, "Resource Indicators for OAuth 2.0", RFC 8707, DOI 10.17487/RFC8707, , <https://www.rfc-editor.org/info/rfc8707>.
- Jones, M., Campbell, B., and C. Mortimore, "JSON Web Token (JWT) Profile for OAuth 2.0 Client Authentication and Authorization Grants", RFC 7523, DOI 10.17487/RFC7523, , <https://www.rfc-editor.org/info/rfc7523>.
- 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, "JSON Web Token Claims", <http://www.iana.org/assignments/jwt>.
- 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>.
- IANA, "Hypertext Transfer Protocol (HTTP) Authentication Scheme Registry", <https://www.iana.org/assignments/http-authschemes>.
- IANA, "Structured Syntax Suffix Registry", <https://www.iana.org/assignments/media-type-structured-suffix>.
- 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>.
- 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>.
- 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>.
- IANA, "Media Types", <https://www.iana.org/assignments/media-types>.
- Sakimura, N., Bradley, J., and M. Jones, "The OAuth 2.0 Authorization Framework: JWT Secured Authorization Request (JAR)", Work in Progress, Internet-Draft, draft-ietf-oauth-jwsreq-30, , <https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-30>.
Appendix A. Acknowledgements
We would like to thank Annabelle Backman, Dominick Baier, William Denniss, Vladimir Dzhuvinov, Mike Engan, Nikos Fotiou, Mark Haine, Dick Hardt, Bjorn Hjelm, Jared Jennings, Steinar Noem, Neil Madden, Rob Otto, Aaron Parecki, Michael Peck, Paul Querna, Justin Richer, Filip Skokan, Dave Tonge, Jim Willeke, 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 ]]¶
- Lots of editorial updates and additions including expanding on the objectives, better defining the key confirmation representations, example updates and additions, better describing mixed bearer/dpop token type deployments, clarify RT binding only being done for public clients and why, more clearly allow for a bound RT but with bearer AT, explain/justify the choice of SHA-256 for key binding, and more¶
- Require that a protected resource supporting bearer and DPoP at the same time must reject an access token received as bearer, if that token is DPoP-bound¶
- Remove the case-insensitive qualification on the
- Relax the jti tracking requirements a bit and qualify it by URI¶
- Editorial updates¶
- Attempt to more formally define the DPoP Authorization header scheme¶
- Define the 401/WWW-Authenticate challenge¶
invalid_dpop_prooferror code for DPoP errors in token request¶
- Fixed up and added to the IANA section¶
dpop_signing_alg_values_supportedauthorization server metadata¶
- Moved the Acknowledgements into an Appendix and added a bunch of names (best effort)¶
-00 [[ Working Group Draft ]]¶
- Working group draft¶
- rework the text around uniqueness requirements on the jti claim in the DPoP proof JWT¶
- make tokens a bit smaller by using
- more explicit recommendation to use mTLS if that is available¶
- added David Waite as co-author¶
- editorial updates¶
- 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¶
- fixed inconsistencies¶
- moved binding and proof messages to headers instead of parameters¶
- extracted and unified definition of DPoP JWTs¶
- improved description¶
- first draft¶