OAuth 2.0 DPoP for the Implicit Flow
draft-jones-oauth-dpop-implicit-00

Abstract

This specification 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 tokens.

This specification compliments and builds upon the mechanisms defined in draft-fett-oauth-dpop, in which access tokens are returned from the token endpoint. In particular, this specification extends the Demonstration of Proof-of-Possession at the Application Layer (DPoP) mechanisms to also be usable with the OAuth 2.0 implicit flow, in which access tokens are returned from the authorization endpoint.

Status of This Memo

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This Internet-Draft will expire on September 10, 2020.

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Table of Contents

• 1. Introduction
• 1.1. Requirements Notation and Conventions
• 1.2. Terminology
• 2. DPoP for the Implicit Flow
• 2.1. DPoP OAuth Request Parameter
• 2.2. DPoP Proof JWT for the Implicit Flow
• 3. Security Considerations
• 4. IANA Considerations
• 4.1. OAuth Parameters Registration
• 4.1.1. Registry Contents
• 5. References
• 5.1. Normative References
• 5.2. Informative References
• Appendix A. Document History
• Authors' Addresses

1. Introduction

This specification defines additions to the mechanisms defined in [I-D.fett-oauth-dpop] enabling Demonstration of Proof-of-Possession at the Application Layer (DPoP) mechanisms to be used with the OAuth 2.0 implicit flow, in which access tokens are returned from the authorization endpoint. These additions are intended for use with these response_type values: token, id_token token, code token, and code id_token token.

1.1. Requirements Notation and Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

1.2. Terminology

This specification uses the terms "access token", "authorization endpoint", "authorization request", and "token endpoint" defined by The OAuth 2.0 Authorization Framework [RFC6749].

2. DPoP for the Implicit Flow

Demonstration of Proof-of-Possession at the Application Layer (DPoP) for the implicit flow is performed in the same manner as [I-D.fett-oauth-dpop], with this exception: Rather than sending the DPoP proof JWT in a DPoP HTTP header, the DPoP proof JWT is instead sent as the value the new dpop OAuth request parameter, which is defined in this section.

2.1. DPoP OAuth Request Parameter

This specification defines the following OAuth request parameter for use at the authorization endpoint:

dpop

The DPoP proof JWT for requests using the implicit flow.

2.2. DPoP Proof JWT for the Implicit Flow

DPoP proof JWTs used with the implicit flow are as specified in [I-D.fett-oauth-dpop], with the following modifications.

• The value of the htm claim MUST be the HTTP verb used in the authorization request, which is normally GET.
• The value of the htu claim MUST be the URL of the authorization endpoint used in the request.

3. Security Considerations

The security considerations described in [I-D.fett-oauth-dpop] also apply to this specification.

4. IANA Considerations

4.1. OAuth Parameters Registration

This specification registers the following value in the IANA "OAuth Parameters" registry [IANA.OAuth.Parameters] established by [RFC6749].

4.1.1. Registry Contents

• Parameter name: dpop
• Parameter usage location: authorization request
• Change controller: IESG
• Specification document(s): Section 2.1 of [[ this specification ]]

5. References

5.1. Normative References

5.2. Informative References

Appendix A. Document History

[[ to be removed by the RFC Editor before publication as an RFC ]]

-00

• Initial version.

Authors' Addresses