OAuth Working Group M. Jones Internet-Draft Microsoft Intended status: Standards Track B. Campbell, Ed. Expires: September 10, 2020 Ping Identity J. Bradley Yubico March 9, 2020 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 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 September 10, 2020. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. Jones, et al. Expires September 10, 2020 [Page 1] Internet-Draft OAuth 2.0 DPoP for the Implicit Flow March 2020 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Notation and Conventions . . . . . . . . . . 2 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. DPoP for the Implicit Flow . . . . . . . . . . . . . . . . . 3 2.1. DPoP OAuth Request Parameter . . . . . . . . . . . . . . 3 2.2. DPoP Proof JWT for the Implicit Flow . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 4.1. OAuth Parameters Registration . . . . . . . . . . . . . . 3 4.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Normative References . . . . . . . . . . . . . . . . . . 4 5.2. Informative References . . . . . . . . . . . . . . . . . 4 Appendix A. Document History . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 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. Jones, et al. Expires September 10, 2020 [Page 2] Internet-Draft OAuth 2.0 DPoP for the Implicit Flow March 2020 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. o The value of the "htm" claim MUST be the HTTP verb used in the authorization request, which is normally "GET". o 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]. Jones, et al. Expires September 10, 2020 [Page 3] Internet-Draft OAuth 2.0 DPoP for the Implicit Flow March 2020 4.1.1. Registry Contents o Parameter name: dpop o Parameter usage location: authorization request o Change controller: IESG o Specification document(s): Section 2.1 of [[ this specification ]] 5. References 5.1. Normative References [I-D.fett-oauth-dpop] Fett, D., Campbell, B., Bradley, J., Lodderstedt, T., Jones, M., and D. Waite, "OAuth 2.0 Demonstration of Proof-of-Possession at the Application Layer (DPoP)", draft-fett-oauth-dpop-04 (work in progress), March 2020. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, October 2012, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 5.2. Informative References [IANA.OAuth.Parameters] IANA, "OAuth Parameters", . Appendix A. Document History [[ to be removed by the RFC Editor before publication as an RFC ]] -00 o Initial version. Jones, et al. Expires September 10, 2020 [Page 4] Internet-Draft OAuth 2.0 DPoP for the Implicit Flow March 2020 Authors' Addresses Michael B. Jones Microsoft Email: mbj@microsoft.com URI: https://self-issued.info/ Brian Campbell (editor) Ping Identity Email: brian.d.campbell@gmail.com John Bradley Yubico Email: ve7jtb@ve7jtb.com Jones, et al. Expires September 10, 2020 [Page 5]