draft-ietf-oauth-dpop-01.txt   draft-ietf-oauth-dpop-02.txt 
Web Authorization Protocol D. Fett Web Authorization Protocol D. Fett
Internet-Draft yes.com Internet-Draft yes.com
Intended status: Standards Track B. Campbell Intended status: Standards Track B. Campbell
Expires: 2 November 2020 Ping Identity Expires: 22 May 2021 Ping Identity
J. Bradley J. Bradley
Yubico Yubico
T. Lodderstedt T. Lodderstedt
yes.com yes.com
M. Jones M. Jones
Microsoft Microsoft
D. Waite D. Waite
Ping Identity Ping Identity
1 May 2020 18 November 2020
OAuth 2.0 Demonstration of Proof-of-Possession at the Application Layer OAuth 2.0 Demonstrating Proof-of-Possession at the Application Layer
(DPoP) (DPoP)
draft-ietf-oauth-dpop-01 draft-ietf-oauth-dpop-02
Abstract Abstract
This document describes a mechanism for sender-constraining OAuth 2.0 This document describes a mechanism for sender-constraining OAuth 2.0
tokens via a proof-of-possession mechanism on the application level. tokens via a proof-of-possession mechanism on the application level.
This mechanism allows for the detection of replay attacks with access This mechanism allows for the detection of replay attacks with access
and refresh tokens. and refresh tokens.
Status of This Memo Status of This Memo
skipping to change at page 1, line 43 skipping to change at page 1, line 43
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This Internet-Draft will expire on 2 November 2020. This Internet-Draft will expire on 22 May 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions and Terminology . . . . . . . . . . . . . . . 3 1.1. Conventions and Terminology . . . . . . . . . . . . . . . 3
2. Main Objective . . . . . . . . . . . . . . . . . . . . . . . 4 2. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. DPoP Proof JWTs . . . . . . . . . . . . . . . . . . . . . . . 6 4. DPoP Proof JWTs . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. DPoP Proof JWT Syntax . . . . . . . . . . . . . . . . . . 6 4.1. The DPoP HTTP Header . . . . . . . . . . . . . . . . . . 7
4.2. Checking DPoP Proofs . . . . . . . . . . . . . . . . . . 7 4.2. DPoP Proof JWT Syntax . . . . . . . . . . . . . . . . . . 8
5. Token Request (Binding Tokens to a Public Key) . . . . . . . 8 4.3. Checking DPoP Proofs . . . . . . . . . . . . . . . . . . 9
6. Resource Access (Proof of Possession for Access Tokens) . . . 9 5. DPoP Access Token Request . . . . . . . . . . . . . . . . . . 10
7. Public Key Confirmation . . . . . . . . . . . . . . . . . . . 11 5.1. Authorization Server Metadata . . . . . . . . . . . . . . 13
8. Authorization Server Metadata . . . . . . . . . . . . . . . . 12 6. Public Key Confirmation . . . . . . . . . . . . . . . . . . . 13
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 6.1. JWK Thumbprint Confirmation Method . . . . . . . . . . . 14
9.1. DPoP Proof Replay . . . . . . . . . . . . . . . . . . . . 13 6.2. JWK Thumbprint Confirmation Method in Token
9.2. Signed JWT Swapping . . . . . . . . . . . . . . . . . . . 13 Introspection . . . . . . . . . . . . . . . . . . . . . . 14
9.3. Signature Algorithms . . . . . . . . . . . . . . . . . . 13 7. Protected Resource Access . . . . . . . . . . . . . . . . . . 16
9.4. Message Integrity . . . . . . . . . . . . . . . . . . . . 13 7.1. The DPoP Authorization Request Header Scheme . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7.2. The Bearer Authorization Request Header Scheme . . . . . 18
10.1. OAuth Access Token Type Registration . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10.2. HTTP Authentication Scheme Registration . . . . . . . . 14 8.1. DPoP Proof Replay . . . . . . . . . . . . . . . . . . . . 19
10.3. Media Type Registration . . . . . . . . . . . . . . . . 14 8.2. Signed JWT Swapping . . . . . . . . . . . . . . . . . . . 19
10.4. JWT Confirmation Methods Registration . . . . . . . . . 15 8.3. Signature Algorithms . . . . . . . . . . . . . . . . . . 19
10.5. JSON Web Token Claims Registration . . . . . . . . . . . 15 8.4. Message Integrity . . . . . . . . . . . . . . . . . . . . 20
10.6. HTTP Message Header Field Names Registration . . . . . . 15 8.5. Public Key Binding . . . . . . . . . . . . . . . . . . . 20
10.7. Authorization Server Metadata Registration . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
11. Normative References . . . . . . . . . . . . . . . . . . . . 16 9.1. OAuth Access Token Type Registration . . . . . . . . . . 20
12. Informative References . . . . . . . . . . . . . . . . . . . 17 9.2. HTTP Authentication Scheme Registration . . . . . . . . . 21
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 19 9.3. Media Type Registration . . . . . . . . . . . . . . . . . 21
Appendix B. Document History . . . . . . . . . . . . . . . . . . 19 9.4. JWT Confirmation Methods Registration . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 9.5. JSON Web Token Claims Registration . . . . . . . . . . . 22
9.6. HTTP Message Header Field Names Registration . . . . . . 22
9.7. Authorization Server Metadata Registration . . . . . . . 22
10. Normative References . . . . . . . . . . . . . . . . . . . . 23
11. Informative References . . . . . . . . . . . . . . . . . . . 23
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 26
Appendix B. Document History . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction 1. Introduction
This document outlines a relatively simple application-level DPoP, an abbreviation for Demonstrating Proof-of-Possession at the
mechanism for sender-constraining OAuth access and refresh tokens. Application Layer, is an application-level mechanism for sender-
It enables a client to demonstrate proof-of-possession of a public/ constraining OAuth access and refresh tokens. It enables a client to
private key pair by including the "DPoP" header in an HTTP request. demonstrate proof-of-possession of a public/private key pair by
Using that header, an authorization server is able to bind issued including a "DPoP" header in an HTTP request. The value of the
tokens to the public part of the client's key pair. Recipients of header is a JWT [RFC7519] that enables the authorization server to
such tokens are then able to verify the binding of the token to the bind issued tokens to the public part of the client's key pair.
key pair that the client has demonstrated that it holds via the Recipients of such tokens are then able to verify the binding of the
"DPoP" header, thereby providing some assurance that the client token to the key pair that the client has demonstrated that it holds
presenting the token also possesses the private key. In other words, via the "DPoP" header, thereby providing some assurance that the
the legitimate presenter of the token is constrained to be the sender client presenting the token also possesses the private key. In other
that holds and can prove possession of the private part of the key words, the legitimate presenter of the token is constrained to be the
pair. 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 The mechanism described herein can be used in cases where other
stronger methods of sender-constraining tokens that utilize elements methods of sender-constraining tokens that utilize elements of the
of the underlying secure transport layer, such as [RFC8705] or underlying secure transport layer, such as [RFC8705] or
[I-D.ietf-oauth-token-binding], are not available or desirable. For [I-D.ietf-oauth-token-binding], are not available or desirable. For
example, due to a sub-par user experience of TLS client example, due to a sub-par user experience of TLS client
authentication in user agents and a lack of support for HTTP token 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 binding, neither mechanism can be used if an OAuth client is a Single
Page Application (SPA) running in a web browser. 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 with public clients to sender-constrain access DPoP can be used to sender-constrain access tokens regardless of the
tokens and refresh tokens. With confidential clients, DPoP can be client authentication method employed. Furthermore, DPoP can also be
used in conjunction with any client authentication method to sender- used to sender-constrain refresh tokens issued to public clients
constrain access tokens. (those without authentication credentials associated with the
"client_id").
1.1. Conventions and Terminology 1.1. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This specification uses the terms "access token", "refresh token", This specification uses the terms "access token", "refresh token",
"authorization server", "resource server", "authorization endpoint", "authorization server", "resource server", "authorization endpoint",
"authorization request", "authorization response", "token endpoint", "authorization request", "authorization response", "token endpoint",
"grant type", "access token request", "access token response", and "grant type", "access token request", "access token response", and
"client" defined by The OAuth 2.0 Authorization Framework [RFC6749]. "client" defined by The OAuth 2.0 Authorization Framework [RFC6749].
2. Main Objective 2. Objectives
Under the attacker model defined in [I-D.ietf-oauth-security-topics], The primary aim of DPoP is to prevent unauthorized or illegitimate
the mechanism defined by this specification aims to prevent token parties from using leaked or stolen access tokens by binding a token
replay at a different endpoint. 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.
More precisely, if an adversary is able to get hold of an access Access tokens that are sender-constrained via DPoP thus stand in
token or refresh token because it set up a counterfeit authorization contrast to the typical bearer token, which can be used by any party
server or resource server, the adversary is not able to replay the in possession of such a token. Although protections generally exist
respective token at another authorization or resource server. 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.
Secondary objectives are discussed in Section 9. 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.
3. Concept 3. Concept
The main data structure introduced by this specification is a DPoP The main data structure introduced by this specification is a DPoP
proof JWT, described in detail below, sent as a header in an HTTP proof JWT, described in detail below, which is sent as a header in an
request. A client uses a DPoP proof JWT to prove the possession of a HTTP request. A client uses a DPoP proof JWT to prove the possession
private key corresponding to a certain public key. Roughly speaking, of a private key corresponding to a certain public key. Roughly
a DPoP proof is a signature over a timestamp and some data of the speaking, a DPoP proof is a signature over a timestamp and some data
HTTP request to which it is attached. of the HTTP request to which it is attached.
+--------+ +---------------+ +--------+ +---------------+
| |--(A)-- Token Request ------------------->| | | |--(A)-- Token Request ------------------->| |
| Client | (DPoP Proof) | Authorization | | Client | (DPoP Proof) | Authorization |
| | | Server | | | | Server |
| |<-(B)-- DPoP-bound Access Token ----------| | | |<-(B)-- DPoP-bound Access Token ----------| |
| | (token_type=DPoP) +---------------+ | | (token_type=DPoP) +---------------+
| | PoP Refresh Token for public clients | |
| | | |
| | +---------------+ | | +---------------+
| |--(C)-- DPoP-bound Access Token --------->| | | |--(C)-- DPoP-bound Access Token --------->| |
| | (DPoP Proof) | Resource | | | (DPoP Proof) | Resource |
| | | Server | | | | Server |
| |<-(D)-- Protected Resource ---------------| | | |<-(D)-- Protected Resource ---------------| |
| | +---------------+ | | +---------------+
+--------+ +--------+
Figure 1: Basic DPoP Flow Figure 1: Basic DPoP Flow
The basic steps of an OAuth flow with DPoP are shown in Figure 1: 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 * (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 to the authorization server in order to obtain an access token
(and potentially a refresh token). The client attaches a DPoP (and potentially a refresh token). The client attaches a DPoP
proof to the request in an HTTP header. proof to the request in an HTTP header.
* (B) The AS binds (sender-constrains) the access token to the * (B) The authorization server binds (sender-constrains) the access
public key claimed by the client in the DPoP proof; that is, the token to the public key claimed by the client in the DPoP proof;
access token cannot be used without proving possession of the that is, the access token cannot be used without proving
respective private key. This is signaled to the client by using possession of the respective private key. If a refresh token is
the "token_type" value "DPoP". issued to a public client, it too is bound to the public key of
the DPoP proof.
* 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 * (C) To use the access token the client has to prove possession of
possession of the private key by, again, adding a header to the the private key by, again, adding a header to the request that
request that carries the DPoP proof. The resource server needs to carries the DPoP proof. The resource server needs to receive
receive information about the public key to which the access token information about the public key to which the access token is
is bound. This information is either encoded directly into the bound. This information may be encoded directly into the access
access token (for JWT structured access tokens), or provided at token (for JWT structured access tokens) or provided via token
the token introspection endpoint of the authorization server (not introspection endpoint (not shown). The resource server verifies
shown). The resource server verifies that the public key to which that the public key to which the access token is bound matches the
the access token is bound matches the public key of the DPoP public key of the DPoP proof.
proof.
* (D) The resource server refuses to serve the request if the * (D) The resource server refuses to serve the request if the
signature check fails or the data in the DPoP proof is wrong, 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 e.g., the request URI does not match the URI claim in the DPoP
proof JWT. proof JWT. The access token itself, of course, must also be valid
in all other respects.
* 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. The DPoP mechanism presented herein is not a client authentication
In fact, a primary use case of DPoP is for public clients (e.g., method. In fact, a primary use case of DPoP is for public clients
single page applications) that do not use client authentication. (e.g., single page applications and native applications) that do not
Nonetheless, DPoP is designed such that it is compatible with use client authentication. Nonetheless, DPoP is designed such that
"private_key_jwt" and all other client authentication methods. 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 DPoP does not directly ensure message integrity but relies on the TLS
layer for that purpose. See Section 9 for details. layer for that purpose. See Section 8 for details.
4. DPoP Proof JWTs 4. DPoP Proof JWTs
DPoP introduces concept of a DPoP proof JWT, which is used for DPoP introduces the concept of a DPoP proof, which is a JWT created
binding public keys and proving knowledge about private keys. The by the client and sent with an HTTP request using the "DPoP" header
DPoP proof JWT is sent with an HTTP request using the "DPoP" header field. A valid DPoP proof demonstrates to the server that the client
field. 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.
4.1. DPoP Proof JWT Syntax 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.
"DPoP" 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).
DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik
VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR
nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE
QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj
oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia
WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg
4PtFLbdLXiOSsX0x7NVY-FNyJK70nfbV37xRZT3Lg
Figure 2: Example "DPoP" header
Note that per [RFC7230] header field names are case-insensitive; so
"DPoP", "DPOP", "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, A DPoP proof is a JWT ([RFC7519]) that is signed (using JWS,
[RFC7515]) using a private key chosen by the client (see below). The [RFC7515]) with a private key chosen by the client (see below). The
header of a DPoP JWT contains at least the following parameters: header of a DPoP JWT contains at least the following parameters:
* "typ": type header, value "dpop+jwt" (REQUIRED). * "typ": type header, value "dpop+jwt" (REQUIRED).
* "alg": a digital signature algorithm identifier as per [RFC7518] * "alg": a digital signature algorithm identifier as per [RFC7518]
(REQUIRED). MUST NOT be "none" or an identifier for a symmetric (REQUIRED). MUST NOT be "none" or an identifier for a symmetric
algorithm (MAC). algorithm (MAC).
* "jwk": representing the public key chosen by the client, in JWK * "jwk": representing the public key chosen by the client, in JWK
format, as defined in [RFC7515] (REQUIRED) format, as defined in [RFC7515] (REQUIRED)
The body of a DPoP proof contains at least the following claims: The body of a DPoP proof contains at least the following claims:
* "jti": Unique identifier for the DPoP proof JWT (REQUIRED). The * "jti": Unique identifier for the DPoP proof JWT (REQUIRED). The
value MUST be assigned such that there is a negligible probability value MUST be assigned such that there is a negligible probability
that the same value will be assigned to any other DPoP proof used that the same value will be assigned to any other DPoP proof used
in the same context during the time window of validity. Such in the same context during the time window of validity. Such
uniqueness can be accomplished by encoding (base64url or any other uniqueness can be accomplished by encoding (base64url or any other
suitable encoding) at least 96 bits of pseudorandom data or by suitable encoding) at least 96 bits of pseudorandom data or by
using a version 4 UUID string according to [RFC4122]. The "jti" using a version 4 UUID string according to [RFC4122]. The "jti"
SHOULD be used by the server for replay detection and prevention, can be used by the server for replay detection and prevention, see
see Section 9.1. Section 8.1.
* "htm": The HTTP method for the request to which the JWT is * "htm": The HTTP method for the request to which the JWT is
attached, as defined in [RFC7231] (REQUIRED). attached, as defined in [RFC7231] (REQUIRED).
* "htu": The HTTP URI used for the request, without query and * "htu": The HTTP URI used for the request, without query and
fragment parts (REQUIRED). fragment parts (REQUIRED).
* "iat": Time at which the JWT was created (REQUIRED). * "iat": Time at which the JWT was created (REQUIRED).
Figure 2 shows the JSON header and payload of a DPoP proof JWT. 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.
{ {
"typ":"dpop+jwt", "typ":"dpop+jwt",
"alg":"ES256", "alg":"ES256",
"jwk": { "jwk": {
"kty":"EC", "kty":"EC",
"x":"l8tFrhx-34tV3hRICRDY9zCkDlpBhF42UQUfWVAWBFs", "x":"l8tFrhx-34tV3hRICRDY9zCkDlpBhF42UQUfWVAWBFs",
"y":"9VE4jf_Ok_o64zbTTlcuNJajHmt6v9TDVrU0CdvGRDA", "y":"9VE4jf_Ok_o64zbTTlcuNJajHmt6v9TDVrU0CdvGRDA",
"crv":"P-256" "crv":"P-256"
} }
}.{ }
.
{
"jti":"-BwC3ESc6acc2lTc", "jti":"-BwC3ESc6acc2lTc",
"htm":"POST", "htm":"POST",
"htu":"https://server.example.com/token", "htu":"https://server.example.com/token",
"iat":1562262616 "iat":1562262616
} }
Figure 2: Example JWT content for "DPoP" proof header Figure 3: Example JWT content of a "DPoP" proof
Note: To keep DPoP simple to implement, only the HTTP method and URI Of the HTTP content in the request, only the HTTP method and URI are
are signed in DPoP proofs. The idea is sign just enough of the HTTP included in the DPoP JWT, and therefore only these 2 headers of the
data to provide reasonable proof-of-possession with respect to the request are covered by the DPoP proof and its signature. The idea is
HTTP request. But that it be a minimal subset of the HTTP data so as sign just enough of the HTTP data to provide reasonable proof-of-
to avoid the substantial difficulties inherent in attempting to possession with respect to the HTTP request. But that it be a
normalize HTTP messages. Nonetheless, DPoP proofs can be extended to minimal subset of the HTTP data so as to avoid the substantial
contain other information of the HTTP request (see also Section 9.4). 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).
4.2. Checking DPoP Proofs 4.3. Checking DPoP Proofs
To check if a string that was received as part of an HTTP Request is 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 a valid DPoP proof, the receiving server MUST ensure that
1. the string value is a well-formed JWT, 1. the string value is a well-formed JWT,
2. all required claims are contained in the JWT, 2. all required claims are contained in the JWT,
3. the "typ" field in the header has the value "dpop+jwt", 3. the "typ" field in the header has the value "dpop+jwt",
4. the algorithm in the header of the JWT indicates an asymmetric 4. the algorithm in the header of the JWT indicates an asymmetric
digital signature algorithm, is not "none", is supported by the digital signature algorithm, is not "none", is supported by the
application, and is deemed secure, application, and is deemed secure,
5. that the JWT is signed using the public key contained in the 5. that the JWT is signed using the public key contained in the
"jwk" header of the JWT, "jwk" header of the JWT,
6. the "htm" claim matches the HTTP method value of the HTTP request 6. the "htm" claim matches the HTTP method value of the HTTP request
in which the JWT was received (case-insensitive), in which the JWT was received,
7. the "htu" claims matches the HTTP URI value for the HTTP request 7. the "htu" claims matches the HTTPS URI value for the HTTP request
in which the JWT was received, ignoring any query and fragment in which the JWT was received, ignoring any query and fragment
parts, parts,
8. the token was issued within an acceptable timeframe (see 8. the token was issued within an acceptable timeframe (see
Section 9.1), and Section 8.1), and
9. that, within a reasonable consideration of accuracy and resource 9. that, within a reasonable consideration of accuracy and resource
utilization, a JWT with the same "jti" value has not been utilization, a JWT with the same "jti" value has not previously
received previously (see Section 9.1). been received at the same URI (see Section 8.1).
Servers SHOULD employ Syntax-Based Normalization and Scheme-Based Servers SHOULD employ Syntax-Based Normalization and Scheme-Based
Normalization in accordance with Section 6.2.2. and Section 6.2.3. of Normalization in accordance with Section 6.2.2. and Section 6.2.3. of
[RFC3986] before comparing the "htu" claim. [RFC3986] before comparing the "htu" claim.
5. Token Request (Binding Tokens to a Public Key) 5. DPoP Access Token Request
To bind a token to a public key in the token request, the client MUST To request an access token that is bound to a public key using DPoP,
provide a valid DPoP proof JWT in a "DPoP" header. The HTTPS request the client MUST provide a valid DPoP proof JWT in a "DPoP" header
shown in Figure 3 illustrates the protocol for this (with extra line when making an access token request to the authorization server's
breaks for display purposes only). token endpoint. This is applicable for all access token requests
regardless of grant type (including, for example, the common
"authorization_code" and "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 in
the "DPoP" header (extra line breaks and whitespace for display
purposes only).
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8 Content-Type: application/x-www-form-urlencoded;charset=UTF-8
DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik
VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR
nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE
QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj
oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia
WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg
skipping to change at page 8, line 37 skipping to change at page 10, line 47
POST /token HTTP/1.1 POST /token HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8 Content-Type: application/x-www-form-urlencoded;charset=UTF-8
DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik
VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR
nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE
QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj
oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia
WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg
4PtFLbdLXiOSsX0x7NVY-FNyJK70nfbV37xRZT3Lg 4PtFLbdLXiOSsX0x7NVY-FNyJK70nfbV37xRZT3Lg
grant_type=authorization_code grant_type=authorization_code
&code=SplxlOBeZQQYbYS6WxSbIA &code=SplxlOBeZQQYbYS6WxSbIA
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
&code_verifier=bEaL42izcC-o-xBk0K2vuJ6U-y1p9r_wW2dFWIWgjz- &code_verifier=bEaL42izcC-o-xBk0K2vuJ6U-y1p9r_wW2dFWIWgjz-
Figure 4: Token Request for a DPoP sender-constrained token using an
Figure 3: Token Request for a DPoP sender-constrained token authorization code
The "DPoP" HTTP header MUST contain a valid DPoP proof JWT. If the The "DPoP" HTTP header MUST contain a valid DPoP proof JWT. If the
DPoP proof is invalid, the authorization server issues an error DPoP proof is invalid, the authorization server issues an error
response per Section 5.2 of [RFC6749] with "invalid_dpop_proof" as response per Section 5.2 of [RFC6749] with "invalid_dpop_proof" as
the value of the "error" parameter. the value of the "error" parameter.
The authorization server, after checking the validity of the DPoP To sender-constrain the access token, after checking the validity of
proof, associates the access token issued at the token endpoint with the DPoP proof, the authorization server associates the issued access
the public key. It then sets "token_type" to "DPoP" in the token token with the public key from the DPoP proof, which can be
response, which signals to the client that the access token was bound accomplished as described in Section 6. A "token_type" of "DPoP" in
to its DPoP key and can used as described in Section 6. 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 response.
If a refresh token is issued to a public client at the token endpoint HTTP/1.1 200 OK
and a valid DPoP proof is presented, the refresh token MUST be bound Content-Type: application/json
to the public key contained in the header of the DPoP proof JWT. Cache-Control: no-cache, no-store
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 "access_token": "Kz~8mXK1EalYznwH-LC-1fBAo.4Ljp~zsPE_NeO.gxU",
same public key as the one the refresh token is bound to. The access "token_type": "DPoP",
token issued MUST be bound to the public key contained in the DPoP "expires_in": 2677,
proof. "refresh_token": "Q..Zkm29lexi8VnWg2zPW1x-tgGad0Ibc3s3EwM_Ni4-g"
}
6. Resource Access (Proof of Possession for Access Tokens) Figure 5: Access Token Response
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
"refresh_token" 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).
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
WF0IjoxNTYyMjY1Mjk2fQ.pAqut2IRDm_De6PR93SYmGBPXpwrAk90e8cP2hjiaG5Qs
GSuKDYW7_X620BxqhvYC8ynrrvZLTk41mSRroapUA
grant_type=refresh_token
&refresh_token=Q..Zkm29lexi8VnWg2zPW1x-tgGad0Ibc3s3EwM_Ni4-g
Figure 6: Token Request for a DPoP-bound token using a refresh token
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 "token_type" parameter 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 JWS "alg" values the authorization server supports
for DPoP proof JWTs.
"dpop_signing_alg_values_supported" A JSON array containing a list
of the JWS "alg" values 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 using the
"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 "cnf"
claim.
"jkt" JWK SHA-256 Thumbprint Confirmation Method. The value of the
"jkt" member 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.
eyJhbGciOiJFUzI1NiIsImtpZCI6IkJlQUxrYiJ9.eyJzdWIiOiJzb21lb25lQGV4YW1
wbGUuY29tIiwiaXNzIjoiaHR0cHM6Ly9zZXJ2ZXIuZXhhbXBsZS5jb20iLCJuYmYiOjE
1NjIyNjI2MTEsImV4cCI6MTU2MjI2NjIxNiwiY25mIjp7ImprdCI6IjBaY09DT1JaTll
5LURXcHFxMzBqWnlKR0hUTjBkMkhnbEJWM3VpZ3VBNEkifX0.3Tyo8VTcn6u_PboUmAO
YUY1kfAavomW_YwYMkmRNizLJoQzWy2fCo79Zi5yObpIzjWb5xW4OGld7ESZrh0fsrA
Figure 7: JWT containing a JWK SHA-256 Thumbprint Confirmation
{
"sub":"someone@example.com",
"iss":"https://server.example.com",
"nbf":1562262611,
"exp":1562266216,
"cnf":{"jkt":"0ZcOCORZNYy-DWpqq30jZyJGHTN0d2HglBV3uiguA4I"}
}
Figure 8: JWT Claims Set with a JWK SHA-256 Thumbprint Confirmation
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.
POST /as/introspect.oauth2 HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
Authorization: Basic cnM6cnM6TWt1LTZnX2xDektJZHo0ZnNON2tZY3lhK1Rp
token=Kz~8mXK1EalYznwH-LC-1fBAo.4Ljp~zsPE_NeO.gxU
Figure 9: Example Introspection Request
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-cache, no-store
{
"active": true,
"sub": "someone@example.com",
"iss": "https://server.example.com",
"nbf": 1562262611,
"exp": 1562266216,
"cnf": {"jkt": "0ZcOCORZNYy-DWpqq30jZyJGHTN0d2HglBV3uiguA4I"}
}
Figure 10: Example Introspection Response for a DPoP-Bound Access
Token
7. Protected Resource Access
To make use of an access token that is bound to a public key using 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 DPoP, a client MUST prove possession of the corresponding private key
key by providing a DPoP proof in the "DPoP" request header. 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 "Authorization" request A DPoP-bound access token is sent using the "Authorization" request
header field per Section 2 of [RFC7235] using an authentication header field per Section 2 of [RFC7235] using an authentication
scheme of "DPoP". The syntax of the "Authorization" header field for scheme of "DPoP". The syntax of the "Authorization" header field for
the "DPoP" scheme uses the "token68" syntax defined in Section 2.1 of the "DPoP" scheme uses the "token68" syntax defined in Section 2.1 of
[RFC7235] (repeated below for ease of reference) for credentials. [RFC7235] (repeated below for ease of reference) for credentials.
The Augmented Backus-Naur Form (ABNF) notation [RFC5234] syntax for The Augmented Backus-Naur Form (ABNF) notation [RFC5234] syntax for
DPoP Authorization scheme credentials is as follows: DPoP Authorization scheme credentials is as follows:
token68 = 1*( ALPHA / DIGIT / token68 = 1*( ALPHA / DIGIT /
"-" / "." / "_" / "~" / "+" / "/" ) *"=" "-" / "." / "_" / "~" / "+" / "/" ) *"="
credentials = "DPoP" 1*SP token68 credentials = "DPoP" 1*SP token68
Figure 4: DPoP Authorization Scheme ABNF Figure 11: DPoP Authorization Scheme ABNF
For such an access token, a resource server MUST check that a "DPoP" 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 proof was also received in the "DPoP" header field of the HTTP
according to the rules in Section 4.2, and check that the public key request, check the DPoP proof according to the rules in Section 4.3,
of the DPoP proof matches the public key to which the access token is and check that the public key of the DPoP proof matches the public
bound per Section 7. key to which the access token is bound per Section 6.
The resource server MUST NOT grant access to the resource unless all The resource server MUST NOT grant access to the resource unless all
checks are successful. checks are successful.
Figure 12 shows an example request to a protected resource with a
DPoP-bound access token in the "Authorization" header and the DPoP
proof in the "DPoP" header (line breaks and extra whitespace for
display purposes only).
GET /protectedresource HTTP/1.1 GET /protectedresource HTTP/1.1
Host: resource.example.org Host: resource.example.org
Authorization: DPoP eyJhbGciOiJFUzI1NiIsImtpZCI6IkJlQUxrYiJ9.eyJzdWI Authorization: DPoP Kz~8mXK1EalYznwH-LC-1fBAo.4Ljp~zsPE_NeO.gxU
iOiJzb21lb25lQGV4YW1wbGUuY29tIiwiaXNzIjoiaHR0cHM6Ly9zZXJ2ZXIuZXhhbX
BsZS5jb20iLCJhdWQiOiJodHRwczovL3Jlc291cmNlLmV4YW1wbGUub3JnIiwibmJmI
joxNTYyMjYyNjExLCJleHAiOjE1NjIyNjYyMTYsImNuZiI6eyJqa3QiOiIwWmNPQ09S
Wk5ZeS1EV3BxcTMwalp5SkdIVE4wZDJIZ2xCVjN1aWd1QTRJIn19.vsFiVqHCyIkBYu
50c69bmPJsj8qYlsXfuC6nZcLl8YYRNOhqMuRXu6oSZHe2dGZY0ODNaGg1cg-kVigzY
hF1MQ
DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik
VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR
nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE
QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiJlMWozVl9iS2ljOC1MQUVCIiwiaHRtIj QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiJlMWozVl9iS2ljOC1MQUVCIiwiaHRtIj
oiR0VUIiwiaHR1IjoiaHR0cHM6Ly9yZXNvdXJjZS5leGFtcGxlLm9yZy9wcm90ZWN0Z oiR0VUIiwiaHR1IjoiaHR0cHM6Ly9yZXNvdXJjZS5leGFtcGxlLm9yZy9wcm90ZWN0Z
WRyZXNvdXJjZSIsImlhdCI6MTU2MjI2MjYxOH0.lNhmpAX1WwmpBvwhok4E74kWCiGB WRyZXNvdXJjZSIsImlhdCI6MTU2MjI2MjYxOH0.lNhmpAX1WwmpBvwhok4E74kWCiGB
NdavjLAeevGy32H3dbF0Jbri69Nm2ukkwb-uyUI4AUg1JSskfWIyo4UCbQ NdavjLAeevGy32H3dbF0Jbri69Nm2ukkwb-uyUI4AUg1JSskfWIyo4UCbQ
Figure 5: Protected Resource Request with a DPoP sender- Figure 12: DPoP Protected Resource Request
constrained access token
Upon receipt of a request for a URI of a protected resource within Upon receipt of a request for a URI of a protected resource within
the protection space requiring DPoP authorization, if the request the protection space requiring DPoP authorization, if the request
does not include valid credentials or or does not contain an access does not include valid credentials or does not contain an access
token sufficient for access to the protected resource, the server can token sufficient for access to the protected resource, the server can
reply with a challenge using the 401 (Unauthorized) status code reply with a challenge using the 401 (Unauthorized) status code
([RFC7235], Section 3.1) and the "WWW-Authenticate" header field ([RFC7235], Section 3.1) and the "WWW-Authenticate" header field
([RFC7235], Section 4.1). The server MAY include the "WWW- ([RFC7235], Section 4.1). The server MAY include the "WWW-
Authenticate" header in response to other conditions as well. Authenticate" header in response to other conditions as well.
In such challenges: In such challenges:
* The scheme name is "DPoP". * The scheme name is "DPoP".
skipping to change at page 11, line 24 skipping to change at page 18, line 14
* Additional authentication parameters MAY be used and unknown * Additional authentication parameters MAY be used and unknown
parameters MUST be ignored by recipients parameters MUST be ignored by recipients
For example, in response to a protected resource request without For example, in response to a protected resource request without
authentication: authentication:
HTTP/1.1 401 Unauthorized HTTP/1.1 401 Unauthorized
WWW-Authenticate: DPoP realm="WallyWorld", algs="ES256 PS256" WWW-Authenticate: DPoP realm="WallyWorld", algs="ES256 PS256"
Figure 6 Figure 13: HTTP 401 Response To A Protected Resource Request Without
Authentication
And in response to a protected resource request that was rejected And in response to a protected resource request that was rejected
because the confirmation of the DPoP binding in the access token because the confirmation of the DPoP binding in the access token
failed: failed:
HTTP/1.1 401 Unauthorized HTTP/1.1 401 Unauthorized
WWW-Authenticate: DPoP realm="WallyWorld", error="invalid_token", WWW-Authenticate: DPoP realm="WallyWorld", error="invalid_token",
error_description="Invalid DPoP key binding", algs="ES256" error_description="Invalid DPoP key binding", algs="ES256"
Figure 7 Figure 14: HTTP 401 Response To A Protected Resource Request With
An Invalid Token
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"
}
}
Figure 8: Example access token body with "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 7.2. The Bearer Authorization Request Header Scheme
This document introduces the following new authorization server Protected resources simultaneously supporting both the "DPoP" and
metadata [RFC8414] parameter to signal the JWS "alg" values the "Bearer" schemes need to update how evaluation of bearer tokens is
authorization server supports for DPoP proof JWTs: performed to prevent downgraded usage of a DPoP-bound access tokens.
Specifically, such a protected resource MUST reject an access token
received as a bearer token per [!@RFC6750], if that token is
determined to be DPoP-bound.
"dpop_signing_alg_values_supported" OPTIONAL. JSON array containing A protected resource that supports only [RFC6750] and is unaware of
a list of the JWS "alg" values supported by the authorization DPoP would most presumably accept a DPoP-bound access token as a
server for DPoP proof JWTs bearer token (JWT [RFC7519] says to ignore unrecognized claims,
Introspection [RFC7662] says that other parameters might be present
while placing no functional requirements on their presence, and
[RFC6750] is effectively silent on the content of the access token as
it relates to validity). As such, a client MAY send a DPoP-bound
access token using the "Bearer" scheme upon receipt of a "WWW-
Authenticate: Bearer" challenge from a protected resource (or if it
has prior such knowledge about the capabilities of the protected
resource). The effect of this likely simplifies the logistics of
phased upgrades to protected resources in their support DPoP or even
prolonged deployments of protected resources with mixed token type
support.
9. Security Considerations 8. Security Considerations
In DPoP, the prevention of token replay at a different endpoint (see 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 Section 2) is achieved through the binding of the DPoP proof to a
certain URI and HTTP method. DPoP does not, however, achieve the certain URI and HTTP method. DPoP, however, has a somewhat different
same level of protection as TLS-based methods such as OAuth Mutual nature of protection than TLS-based methods such as OAuth Mutual TLS
TLS [RFC8705] or OAuth Token Binding [I-D.ietf-oauth-token-binding] [RFC8705] or OAuth Token Binding [I-D.ietf-oauth-token-binding] (see
(see also Section 9.1 and Section 9.4). TLS-based mechanisms can also Section 8.1 and Section 8.4). TLS-based mechanisms can leverage
leverage a tight integration between the TLS layer and the a tight integration between the TLS layer and the application layer
application layer to achieve a very high level of message integrity to achieve a very high level of message integrity with respect to the
and replay protection. Therefore, it is RECOMMENDED to prefer TLS- transport layer to which the token is bound and replay protection in
based methods over DPoP if such methods are suitable for the scenario general.
at hand.
9.1. DPoP Proof Replay 8.1. DPoP Proof Replay
If an adversary is able to get hold of a DPoP proof JWT, the 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 adversary could replay that token at the same endpoint (the HTTP
endpoint and method are enforced via the respective claims in the endpoint and method are enforced via the respective claims in the
JWTs). To prevent this, servers MUST only accept DPoP proofs for a JWTs). To prevent this, servers MUST only accept DPoP proofs for a
limited time window after their "iat" time, preferably only for a limited time window after their "iat" time, preferably only for a
relatively brief period. Servers SHOULD store the "jti" value of relatively brief period. Servers SHOULD store, in the context of the
each DPoP proof for the time window in which the respective DPoP request URI, the "jti" value of each DPoP proof for the time window
proof JWT would be accepted and decline HTTP requests for which the in which the respective DPoP proof JWT would be accepted and decline
"jti" value has been seen before. In order to guard against memory HTTP requests to the same URI for which the "jti" value has been seen
exhaustion attacks a server SHOULD reject DPoP proof JWTs with before. In order to guard against memory exhaustion attacks a server
unnecessarily large "jti" values or store only a hash thereof. 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 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 proofs that carry an "iat" time in the reasonably near future (e.g.,
seconds in the future). a few seconds in the future).
9.2. Signed JWT Swapping 8.2. Signed JWT Swapping
Servers accepting signed DPoP proof JWTs MUST check the "typ" field Servers accepting signed DPoP proof JWTs MUST check the "typ" field
in the headers of the JWTs to ensure that adversaries cannot use JWTs in the headers of the JWTs to ensure that adversaries cannot use JWTs
created for other purposes. created for other purposes.
9.3. Signature Algorithms 8.3. Signature Algorithms
Implementers MUST ensure that only asymmetric digital signature Implementers MUST ensure that only asymmetric digital signature
algorithms that are deemed secure can be used for signing DPoP algorithms that are deemed secure can be used for signing DPoP
proofs. In particular, the algorithm "none" MUST NOT be allowed. proofs. In particular, the algorithm "none" MUST NOT be allowed.
9.4. Message Integrity 8.4. Message Integrity
DPoP does not ensure the integrity of the payload or headers of DPoP does not ensure the integrity of the payload or headers of
requests. The signature of DPoP proofs only contains the HTTP URI requests. The DPoP proof only contains claims for the HTTP URI and
and method, but not, for example, the message body or other request method, but not, for example, the message body or general request
headers. headers.
This is an intentional design decision to keep DPoP simple to use, This is an intentional design decision intended to keep DPoP simple
but as described, makes DPoP potentially susceptible to replay to use, but as described, makes DPoP potentially susceptible to
attacks where an attacker is able to modify message contents and replay attacks where an attacker is able to modify message contents
headers. In many setups, the message integrity and confidentiality and headers. In many setups, the message integrity and
provided by TLS is sufficient to provide a good level of protection. confidentiality provided by TLS is sufficient to provide a good level
of protection.
Implementers that have stronger requirements on the integrity of Implementers that have stronger requirements on the integrity of
messages are encouraged to either use TLS-based mechanisms or signed messages are encouraged to either use TLS-based mechanisms or signed
requests. TLS-based mechanisms are in particular OAuth Mutual TLS requests. TLS-based mechanisms are in particular OAuth Mutual TLS
[RFC8705] and OAuth Token Binding [I-D.ietf-oauth-token-binding]. [RFC8705] and OAuth Token Binding [I-D.ietf-oauth-token-binding].
Note: While signatures on (parts of) requests are out of the scope of Note: While signatures covering other parts of requests are out of
this specification, signatures or information to be signed can be the scope of this specification, additional information to be signed
added into DPoP proofs. can be added into DPoP proofs.
10. IANA Considerations 8.5. Public Key Binding
10.1. OAuth Access Token Type Registration 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 This specification requests registration of the following access
token type in the "OAuth Access Token Types" registry token type in the "OAuth Access Token Types" registry
[IANA.OAuth.Params] established by [RFC6749]. [IANA.OAuth.Params] established by [RFC6749].
* Type name: "DPoP" * Type name: "DPoP"
* Additional Token Endpoint Response Parameters: (none) * Additional Token Endpoint Response Parameters: (none)
* HTTP Authentication Scheme(s): "DPoP" * HTTP Authentication Scheme(s): "DPoP"
* Change controller: IESG * Change controller: IESG
* Specification document(s): [[ this specification ]] * Specification document(s): [[ this specification ]]
10.2. HTTP Authentication Scheme Registration 9.2. HTTP Authentication Scheme Registration
This specification requests registration of the following scheme in This specification requests registration of the following scheme in
the "Hypertext Transfer Protocol (HTTP) Authentication Scheme the "Hypertext Transfer Protocol (HTTP) Authentication Scheme
Registry" [RFC7235][IANA.HTTP.AuthSchemes]: Registry" [RFC7235][IANA.HTTP.AuthSchemes]:
* Authentication Scheme Name: "DPoP" * Authentication Scheme Name: "DPoP"
* Reference: [[ Section 6 of this specification ]] * Reference: [[ Section 7.1 of this specification ]]
10.3. Media Type Registration 9.3. Media Type Registration
[[ Is a media type registration at [IANA.MediaTypes] necessary for [[ Is a media type registration at [IANA.MediaTypes] necessary for
"application/dpop+jwt"? There is a "+jwt" structured syntax suffix "application/dpop+jwt"? There is a "+jwt" structured syntax suffix
registered already at [IANA.MediaType.StructuredSuffixs] by registered already at [IANA.MediaType.StructuredSuffix] by
Section 7.2 of [RFC8417], which is maybe sufficient? A fullblown Section 7.2 of [RFC8417], which is maybe sufficient? A full-blown
registration of "application/dpop+jwt" seems like it'd be overkill. registration of "application/dpop+jwt" seems like it'd be overkill.
The "dpop+jwt" is used in the JWS/JWT "typ" header for explicit 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 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). anywhere else (such as the "Content-Type" of HTTP messages).
Note that there does seem to be some precedence for [IANA.MediaTypes] Note that there does seem to be some precedence for [IANA.MediaTypes]
registration with [I-D.ietf-oauth-access-token-jwt], registration with [I-D.ietf-oauth-access-token-jwt],
[I-D.ietf-oauth-jwsreq], [RFC8417], and of course [RFC7519]. But [I-D.ietf-oauth-jwsreq], [RFC8417], and of course [RFC7519]. But
precedence isn't always right. ]] precedence isn't always right. ]]
10.4. JWT Confirmation Methods Registration 9.4. JWT Confirmation Methods Registration
This specification requests registration of the following value in This specification requests registration of the following value in
the IANA "JWT Confirmation Methods" registry [IANA.JWT] for JWT "cnf" the IANA "JWT Confirmation Methods" registry [IANA.JWT] for JWT "cnf"
member values established by [RFC7800]. member values established by [RFC7800].
* Confirmation Method Value: "jkt" * Confirmation Method Value: "jkt"
* Confirmation Method Description: JWK SHA-256 Thumbprint * Confirmation Method Description: JWK SHA-256 Thumbprint
* Change Controller: IESG * Change Controller: IESG
* Specification Document(s): [[ Section 7 of this specification ]] * Specification Document(s): [[ Section 6 of this specification ]]
10.5. JSON Web Token Claims Registration 9.5. JSON Web Token Claims Registration
This specification requests registration of the following Claims in This specification requests registration of the following Claims in
the IANA "JSON Web Token Claims" registry [IANA.JWT] established by the IANA "JSON Web Token Claims" registry [IANA.JWT] established by
[RFC7519]. [RFC7519].
HTTP method: HTTP method:
* Claim Name: "htm" * Claim Name: "htm"
* Claim Description: The HTTP method of the request * Claim Description: The HTTP method of the request
* Change Controller: IESG * Change Controller: IESG
* Specification Document(s): [[ Section 4.1 of this specification ]] * Specification Document(s): [[ Section 4.2 of this specification ]]
HTTP URI: HTTP URI:
* Claim Name: "htu" * Claim Name: "htu"
* Claim Description: The HTTP URI of the request (without query and * Claim Description: The HTTP URI of the request (without query and
fragment parts) fragment parts)
* Change Controller: IESG * Change Controller: IESG
* Specification Document(s): [[ Section 4.1 of this specification ]] * Specification Document(s): [[ Section 4.2 of this specification ]]
10.6. HTTP Message Header Field Names Registration 9.6. HTTP Message Header Field Names Registration
This document specifies the following new HTTP header fields, This document specifies the following new HTTP header fields,
registration of which is requested in the "Permanent Message Header registration of which is requested in the "Permanent Message Header
Field Names" registry [IANA.Headers] defined in [RFC3864]. Field Names" registry [IANA.Headers] defined in [RFC3864].
* Header Field Name: "DPoP" * Header Field Name: "DPoP"
* Applicable protocol: HTTP * Applicable protocol: HTTP
* Status: standard * Status: standard
* Author/change Controller: IETF * Author/change Controller: IETF
* Specification Document(s): [[ this specification ]] * Specification Document(s): [[ this specification ]]
10.7. Authorization Server Metadata Registration 9.7. Authorization Server Metadata Registration
This specification requests registration of the following values in This specification requests registration of the following values in
the IANA "OAuth Authorization Server Metadata" registry the IANA "OAuth Authorization Server Metadata" registry
[IANA.OAuth.Parameters] established by [RFC8414]. [IANA.OAuth.Parameters] established by [RFC8414].
* Metadata Name: "dpop_signing_alg_values_supported" * Metadata Name: "dpop_signing_alg_values_supported"
* Metadata Description: JSON array containing a list of the JWS * Metadata Description: JSON array containing a list of the JWS
algorithms supported for DPoP proof JWTs algorithms supported for DPoP proof JWTs
* Change Controller: IESG * Change Controller: IESG
* Specification Document(s): [[ Section 8 of this specification ]] * Specification Document(s): [[ Section 5.1 of this specification ]]
11. Normative References 10. Normative References
[RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of- [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Possession Key Semantics for JSON Web Tokens (JWTs)", Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
RFC 7800, DOI 10.17487/RFC7800, April 2016, 2015, <https://www.rfc-editor.org/info/rfc7515>.
<https://www.rfc-editor.org/info/rfc7800>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
RFC 6749, DOI 10.17487/RFC6749, October 2012, DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc6749>. <https://www.rfc-editor.org/info/rfc7518>.
[RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK)
Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September
2015, <https://www.rfc-editor.org/info/rfc7638>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008, DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>. <https://www.rfc-editor.org/info/rfc5234>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization [RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
Framework: Bearer Token Usage", RFC 6750, Possession Key Semantics for JSON Web Tokens (JWTs)",
DOI 10.17487/RFC6750, October 2012, RFC 7800, DOI 10.17487/RFC7800, April 2016,
<https://www.rfc-editor.org/info/rfc6750>. <https://www.rfc-editor.org/info/rfc7800>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, 11. Informative References
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
[RFC7638] Jones, M. and N. Sakimura, "JSON Web Key (JWK) [I-D.ietf-oauth-security-topics]
Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
2015, <https://www.rfc-editor.org/info/rfc7638>. "OAuth 2.0 Security Best Current Practice", Work in
Progress, Internet-Draft, draft-ietf-oauth-security-
topics-16, 5 October 2020, <https://tools.ietf.org/html/
draft-ietf-oauth-security-topics-16>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7662] Richer, J., Ed., "OAuth 2.0 Token Introspection",
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, RFC 7662, DOI 10.17487/RFC7662, October 2015,
DOI 10.17487/RFC7231, June 2014, <https://www.rfc-editor.org/info/rfc7662>.
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web [IANA.OAuth.Params]
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May IANA, "OAuth Parameters",
2015, <https://www.rfc-editor.org/info/rfc7515>. <https://www.iana.org/assignments/oauth-parameters>.
12. Informative References [RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", BCP 225, RFC 8725,
DOI 10.17487/RFC8725, February 2020,
<https://www.rfc-editor.org/info/rfc8725>.
[I-D.ietf-oauth-token-binding] [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Jones, M., Campbell, B., Bradley, J., and W. Denniss, Procedures for Message Header Fields", BCP 90, RFC 3864,
"OAuth 2.0 Token Binding", Work in Progress, Internet- DOI 10.17487/RFC3864, September 2004,
Draft, draft-ietf-oauth-token-binding-08, 19 October 2018, <https://www.rfc-editor.org/info/rfc3864>.
<https://tools.ietf.org/html/draft-ietf-oauth-token-
binding-08>. [RFC8414] Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
Authorization Server Metadata", RFC 8414,
DOI 10.17487/RFC8414, June 2018,
<https://www.rfc-editor.org/info/rfc8414>.
[I-D.ietf-oauth-access-token-jwt] [I-D.ietf-oauth-access-token-jwt]
Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0 Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0
Access Tokens", Work in Progress, Internet-Draft, draft- Access Tokens", Work in Progress, Internet-Draft, draft-
ietf-oauth-access-token-jwt-07, 27 April 2020, ietf-oauth-access-token-jwt-10, 23 September 2020,
<https://tools.ietf.org/html/draft-ietf-oauth-access- <https://tools.ietf.org/html/draft-ietf-oauth-access-
token-jwt-07>. token-jwt-10>.
[I-D.ietf-oauth-jwsreq] [IANA.Headers]
Sakimura, N. and J. Bradley, "The OAuth 2.0 Authorization IANA, "Message Headers",
Framework: JWT Secured Authorization Request (JAR)", Work <https://www.iana.org/assignments/message-headers>.
in Progress, Internet-Draft, draft-ietf-oauth-jwsreq-21,
19 April 2020, [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
<https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-21>. (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[W3C.WebCryptoAPI]
Watson, M., "Web Cryptography API", 26 January 2017,
<https://www.w3.org/TR/2017/REC-WebCryptoAPI-20170126>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC8705] Campbell, B., Bradley, J., Sakimura, N., and T. [RFC8705] Campbell, B., Bradley, J., Sakimura, N., and T.
Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication
and Certificate-Bound Access Tokens", RFC 8705, and Certificate-Bound Access Tokens", RFC 8705,
DOI 10.17487/RFC8705, February 2020, DOI 10.17487/RFC8705, February 2020,
<https://www.rfc-editor.org/info/rfc8705>. <https://www.rfc-editor.org/info/rfc8705>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8707] Campbell, B., Bradley, J., and H. Tschofenig, "Resource
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, Indicators for OAuth 2.0", RFC 8707, DOI 10.17487/RFC8707,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. February 2020, <https://www.rfc-editor.org/info/rfc8707>.
[IANA.MediaTypes]
IANA, "Media Types",
<https://www.iana.org/assignments/media-types>.
[RFC8414] Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0 [RFC7523] Jones, M., Campbell, B., and C. Mortimore, "JSON Web Token
Authorization Server Metadata", RFC 8414, (JWT) Profile for OAuth 2.0 Client Authentication and
DOI 10.17487/RFC8414, June 2018, Authorization Grants", RFC 7523, DOI 10.17487/RFC7523, May
<https://www.rfc-editor.org/info/rfc8414>. 2015, <https://www.rfc-editor.org/info/rfc7523>.
[RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
"Security Event Token (SET)", RFC 8417, Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC8417, July 2018, DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc8417>. <https://www.rfc-editor.org/info/rfc7235>.
[IANA.JWT] IANA, "JSON Web Token Claims", [IANA.JWT] IANA, "JSON Web Token Claims",
<http://www.iana.org/assignments/jwt>. <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, September 2004,
<https://www.rfc-editor.org/info/rfc3864>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token [IANA.HTTP.AuthSchemes]
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, IANA, "Hypertext Transfer Protocol (HTTP) Authentication
<https://www.rfc-editor.org/info/rfc7519>. Scheme Registry",
<https://www.iana.org/assignments/http-authschemes>.
[IANA.OAuth.Params]
IANA, "OAuth Parameters",
<https://www.iana.org/assignments/oauth-parameters>.
[IANA.MediaType.StructuredSuffixs] [IANA.MediaType.StructuredSuffix]
IANA, "Structured Syntax Suffix Registry", IANA, "Structured Syntax Suffix Registry",
<https://www.iana.org/assignments/media-type-structured- <https://www.iana.org/assignments/media-type-structured-
suffixs>. suffix>.
[IANA.Headers]
IANA, "Message Headers",
<https://www.iana.org/assignments/message-headers>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari,
Protocol (HTTP/1.1): Authentication", RFC 7235, "Security Event Token (SET)", RFC 8417,
DOI 10.17487/RFC7235, June 2014, DOI 10.17487/RFC8417, July 2018,
<https://www.rfc-editor.org/info/rfc7235>. <https://www.rfc-editor.org/info/rfc8417>.
[IANA.HTTP.AuthSchemes] [I-D.ietf-oauth-token-binding]
IANA, "Hypertext Transfer Protocol (HTTP) Authentication Jones, M., Campbell, B., Bradley, J., and W. Denniss,
Scheme Registry", "OAuth 2.0 Token Binding", Work in Progress, Internet-
<https://www.iana.org/assignments/http-authschemes>. Draft, draft-ietf-oauth-token-binding-08, 19 October 2018,
<https://tools.ietf.org/html/draft-ietf-oauth-token-
binding-08>.
[RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Current Practices", BCP 225, RFC 8725, Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC8725, February 2020, DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/info/rfc8725>. <https://www.rfc-editor.org/info/rfc6750>.
[I-D.ietf-oauth-security-topics] [IANA.MediaTypes]
Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett, IANA, "Media Types",
"OAuth 2.0 Security Best Current Practice", Work in <https://www.iana.org/assignments/media-types>.
Progress, Internet-Draft, draft-ietf-oauth-security-
topics-15, 5 April 2020, <https://tools.ietf.org/html/
draft-ietf-oauth-security-topics-15>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally [I-D.ietf-oauth-jwsreq]
Unique IDentifier (UUID) URN Namespace", RFC 4122, Sakimura, N., Bradley, J., and M. Jones, "The OAuth 2.0
DOI 10.17487/RFC4122, July 2005, Authorization Framework: JWT Secured Authorization Request
<https://www.rfc-editor.org/info/rfc4122>. (JAR)", Work in Progress, Internet-Draft, draft-ietf-
oauth-jwsreq-30, 10 September 2020,
<https://tools.ietf.org/html/draft-ietf-oauth-jwsreq-30>.
Appendix A. Acknowledgements Appendix A. Acknowledgements
We would like to thank Filip Skokan, Mike Engan, Justin Richer, We would like to thank Annabelle Backman, Dominick Baier, William
Michael Peck, Vladimir Dzhuvinov, Rob Otto, Dominick Baier, Jim Denniss, Vladimir Dzhuvinov, Mike Engan, Nikos Fotiou, Mark Haine,
Willeke, Annabelle Backman, Bjorn Hjelm, Steinar Noem, Aaron Parecki, Dick Hardt, Bjorn Hjelm, Jared Jennings, Steinar Noem, Neil Madden,
Neil Madden, Paul Querna, Dick Hardt, Dave Tonge, Jared Jennings, Rob Otto, Aaron Parecki, Michael Peck, Paul Querna, Justin Richer,
Mark Haine and others (please let us know, if you've been mistakenly Filip Skokan, Dave Tonge, Jim Willeke, and others (please let us
omitted) for their valuable input, feedback and general support of know, if you've been mistakenly omitted) for their valuable input,
this work. feedback and general support of this work.
This document resulted from discussions at the 4th OAuth Security This document resulted from discussions at the 4th OAuth Security
Workshop in Stuttgart, Germany. We thank the organizers of this Workshop in Stuttgart, Germany. We thank the organizers of this
workshop (Ralf Kusters, Guido Schmitz). workshop (Ralf Kusters, Guido Schmitz).
Appendix B. Document History Appendix B. Document History
[[ To be removed from the final specification ]] [[ To be removed from the final specification ]]
-02
* 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 "htm" claim check
* Relax the jti tracking requirements a bit and qualify it by URI
-01 -01
* Editorial updates * Editorial updates
* Attempt to more formally define the DPoP Authorization header * Attempt to more formally define the DPoP Authorization header
scheme scheme
* Define the 401/WWW-Authenticate challenge * Define the 401/WWW-Authenticate challenge
* Added "invalid_dpop_proof" error code for DPoP errors in token * Added "invalid_dpop_proof" error code for DPoP errors in token
request request
* Fixed up and added to the IANA section * Fixed up and added to the IANA section
 End of changes. 111 change blocks. 
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