OAuth Working Group M. Jones Internet-Draft Microsoft Intended status: Standards Track P. Hunt Expires: February 22, 2016 Oracle A. Nadalin Microsoft August 21, 2015 Authentication Method Reference Values draft-jones-oauth-amr-values-02 Abstract The "amr" (Authentication Methods References) claim is defined and registered in the IANA "JSON Web Token Claims" registry but no standard Authentication Method Reference values are currently defined. This specification establishes a registry for Authentication Method Reference values and defines an initial set of Authentication Method Reference values. It also defines the "amr_values" (requested Authentication Method Reference values) request parameter for requesting that a set of Authentication Method Reference values be used for processing the Authentication Request. 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 http://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 February 22, 2016. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Jones, et al. Expires February 22, 2016 [Page 1] Internet-Draft Authentication Method Reference Values August 2015 (http://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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Notation and Conventions . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Authentication Method Reference Values . . . . . . . . . . . . 3 3. Authentication Request Parameter . . . . . . . . . . . . . . . 5 4. Relationship to "acr" (Authentication Context Class Reference) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7.1. Authentication Method Reference Values Registry . . . . . 6 7.1.1. Registration Template . . . . . . . . . . . . . . . . 7 7.1.2. Initial Registry Contents . . . . . . . . . . . . . . 7 7.2. OAuth Parameters Registration . . . . . . . . . . . . . . 9 7.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Normative References . . . . . . . . . . . . . . . . . . . 10 8.2. Informative References . . . . . . . . . . . . . . . . . . 11 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11 Appendix B. Document History . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Jones, et al. Expires February 22, 2016 [Page 2] Internet-Draft Authentication Method Reference Values August 2015 1. Introduction The "amr" (Authentication Methods References) claim is defined and registered in the IANA "JSON Web Token Claims" registry [IANA.JWT.Claims] but no standard Authentication Method Reference values are currently defined. This specification establishes a registry for Authentication Method Reference values and defines an initial set of Authentication Method Reference values. It also defines the "amr_values" (requested Authentication Method Reference values) request parameter for requesting that a set of Authentication Method Reference values be used for processing the Authentication Request. 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 RFC 2119 [RFC2119]. 1.2. Terminology This specification uses the terms defined by JSON Web Token (JWT) [JWT] and OpenID Connect Core 1.0 [OpenID.Core]. 2. Authentication Method Reference Values The "amr" (Authentication Methods References) claim is defined by the OpenID Connect Core 1.0 specification [OpenID.Core] as follows: amr OPTIONAL. Authentication Methods References. JSON array of strings that are identifiers for authentication methods used in the authentication. For instance, values might indicate that both password and OTP authentication methods were used. The definition of particular values to be used in the "amr" Claim is beyond the scope of this specification. Parties using this claim will need to agree upon the meanings of the values used, which may be context-specific. The "amr" value is an array of case sensitive strings. However, OpenID Connect does not specify any particular Authentication Method Reference values to be used in the "amr" claim. The following is a list of Authentication Method Reference values defined by this specification: Jones, et al. Expires February 22, 2016 [Page 3] Internet-Draft Authentication Method Reference Values August 2015 eye Retina scan biometric fpt Fingerprint biometric kba Knowledge-based authentication [NIST.800-63-2] mca Multiple-channel authentication. The authentication involves communication over more than one distinct channel. mfa Multiple-factor authentication [NIST.800-63-2]. When this is present, specific authentication methods used may also be included. otp One-time password. One-time password specifications that this authentication method applies to include [RFC4226] and [RFC6238]. pop Proof-of-possession (PoP) of a key. See Appendix C of [RFC4211] for a discussion on PoP. pwd Password-based authentication rba Risk-based authentication [JECM] sc Smart card sms Confirmation by SMS reply tel Confirmation by telephone call user User presence test vbm Voice biometric Jones, et al. Expires February 22, 2016 [Page 4] Internet-Draft Authentication Method Reference Values August 2015 wia Windows integrated authentication, as described in [MSDN] 3. Authentication Request Parameter This section defines the following authentication request parameter, augmenting the set of authentication request parameters defined in Section 3.1.2.1 of OpenID Connect Core 1.0 [OpenID.Core]: amr_values OPTIONAL. Requested Authentication Method Reference values. Space-separated string that specifies the "amr" values that the Authorization Server is being requested to use for processing this Authentication Request, with the values appearing in order of preference. The authentication methods used for the authentication performed are returned as the "amr" Claim Value. 4. Relationship to "acr" (Authentication Context Class Reference) The "acr" (Authentication Context Class Reference) claim and "acr_values" request parameter are related to the "amr" (Authentication Methods References) claim and "amr_values" request parameter, but with important differences. An Authentication Context Class specifies a set of business rules that authentications are being requested to satisfy. These rules can often be satisfied by using a number of different specific authentication methods, either singly or in combination. Interactions using "acr_values" request that the specified Authentication Context Classes be used and that the result should contain an "acr" claim saying which Authentication Context Class was satisfied. The "acr" claim in the reply states that the business rules for the class were satisfied -- not how they were was satisfied. In contrast, interactions using "amr_values" and/or "amr" make statements about the particular authentication methods that are being requested and that were used. This tends to be more brittle than using "acr", since the authentication methods that may be appropriate for a given authentication will vary over time, both because of the evolution of attacks on existing methods and the deployment of new authentication methods. 5. Privacy Considerations The list of "amr" claim values returned in an ID Token reveals information about the way that the end-user authenticated to the Jones, et al. Expires February 22, 2016 [Page 5] Internet-Draft Authentication Method Reference Values August 2015 identity provider. In some cases, this information may have privacy implications. 6. Security Considerations The security considerations in OpenID Connect Core 1.0 [OpenID.Core], OAuth 2.0 [RFC6749], and the OAuth 2.0 Threat Model [RFC6819] apply to this specification. As described in Section 4, taking a dependence upon particular authentication methods may result in brittle systems, since the authentication methods that may be appropriate for a given authentication will vary over time. 7. IANA Considerations 7.1. Authentication Method Reference Values Registry This specification establishes the IANA "Authentication Method Reference Values" registry for "amr" claim array element values. The registry records the Authentication Method Reference value and a reference to the specification that defines it. This specification registers the Authentication Method Reference values defined in Section 2. Values are registered on a Specification Required [RFC5226] basis after a three-week review period on the jwt-reg-review@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of values prior to publication, the Designated Experts may approve registration once they are satisfied that such a specification will be published. Registration requests sent to the mailing list for review should use an appropriate subject (e.g., "Request to register Authentication Method Reference value: otp"). Within the review period, the Designated Experts will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful. Registration requests that are undetermined for a period longer than 21 days can be brought to the IESG's attention (using the iesg@ietf.org mailing list) for resolution. Criteria that should be applied by the Designated Experts includes determining whether the proposed registration duplicates existing Jones, et al. Expires February 22, 2016 [Page 6] Internet-Draft Authentication Method Reference Values August 2015 functionality, whether it is likely to be of general applicability or whether it is useful only for a single application, and whether the registration description is clear. IANA must only accept registry updates from the Designated Experts and should direct all requests for registration to the review mailing list. It is suggested that the same Designated Experts evaluate these registration requests as those who evaluate registration requests for the IANA "JSON Web Token Claims" registry [IANA.JWT.Claims]. 7.1.1. Registration Template Authentication Method Reference Name: The name requested (e.g., "otp"). Because a core goal of this specification is for the resulting representations to be compact, it is RECOMMENDED that the name be short -- that is, not to exceed 8 characters without a compelling reason to do so. This name is case sensitive. Names may not match other registered names in a case-insensitive manner unless the Designated Experts state that there is a compelling reason to allow an exception. Authentication Method Reference Description: Brief description of the Authentication Method Reference (e.g., "One-time password"). Change Controller: For Standards Track RFCs, state "IESG". For others, give the name of the responsible party. Other details (e.g., postal address, email address, home page URI) may also be included. Specification Document(s): Reference to the document or documents that specify the parameter, preferably including URIs that can be used to retrieve copies of the documents. An indication of the relevant sections may also be included but is not required. 7.1.2. Initial Registry Contents o Authentication Method Reference Name: "eye" o Authentication Method Reference Description: Retina scan biometric o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "fpt" Jones, et al. Expires February 22, 2016 [Page 7] Internet-Draft Authentication Method Reference Values August 2015 o Authentication Method Reference Description: Fingerprint biometric o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "kba" o Authentication Method Reference Description: Knowledge-based authentication o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "mca" o Authentication Method Reference Description: Multiple-channel authentication o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "mfa" o Authentication Method Reference Description: Multiple-factor authentication o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "otp" o Authentication Method Reference Description: One-time password o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "pop" o Authentication Method Reference Description: Proof-of-possession of a key o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "pwd" o Authentication Method Reference Description: Password-based authentication o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "rba" o Authentication Method Reference Description: Risk-based authentication o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "sc" Jones, et al. Expires February 22, 2016 [Page 8] Internet-Draft Authentication Method Reference Values August 2015 o Authentication Method Reference Description: Smart card o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "sms" o Authentication Method Reference Description: Confirmation by SMS reply o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "tel" o Authentication Method Reference Description: Confirmation by telephone call o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "user" o Authentication Method Reference Description: User presence test o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "vbm" o Authentication Method Reference Description: Voice biometric o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] o Authentication Method Reference Name: "wia" o Authentication Method Reference Description: Windows integrated authentication o Change Controller: IESG o Specification Document(s): Section 2 of [[ this document ]] 7.2. OAuth Parameters Registration This section registers the following parameter in the IANA "OAuth Parameters" registry [IANA.OAuth.Parameters] established in RFC 6749 [RFC6749]. 7.2.1. Registry Contents o Parameter name: "amr_values" o Parameter usage location: Authorization Request o Change controller: IESG o Specification document(s): Section 3 of [[ this document ]] o Related information: None 8. References Jones, et al. Expires February 22, 2016 [Page 9] Internet-Draft Authentication Method Reference Values August 2015 8.1. Normative References [IANA.JWT.Claims] IANA, "JSON Web Token Claims", . [IANA.OAuth.Parameters] IANA, "OAuth Parameters", . [JECM] Williamson, G., "Enhanced Authentication In Online Banking", Journal of Economic Crime Management 4.2: 18-19, 2006, . [JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, May 2015, . [MSDN] Microsoft, "Integrated Windows Authentication with Negotiate", September 2011, . [NIST.800-63-2] National Institute of Standards and Technology (NIST), "Electronic Authentication Guideline", NIST Special Publication 800-63-2, August 2013, . [OpenID.Core] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and C. Mortimore, "OpenID Connect Core 1.0", November 2014. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ RFC2119, March 1997, . [RFC4211] Schaad, J., "Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF)", RFC 4211, DOI 10.17487/RFC4211, September 2005, . [RFC4226] M'Raihi, D., Bellare, M., Hoornaert, F., Naccache, D., and Jones, et al. Expires February 22, 2016 [Page 10] Internet-Draft Authentication Method Reference Values August 2015 O. Ranen, "HOTP: An HMAC-Based One-Time Password Algorithm", RFC 4226, DOI 10.17487/RFC4226, December 2005, . [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, . [RFC6238] M'Raihi, D., Machani, S., Pei, M., and J. Rydell, "TOTP: Time-Based One-Time Password Algorithm", RFC 6238, DOI 10.17487/RFC6238, May 2011, . [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, October 2012, . 8.2. Informative References [RFC6819] Lodderstedt, T., Ed., McGloin, M., and P. Hunt, "OAuth 2.0 Threat Model and Security Considerations", RFC 6819, DOI 10.17487/RFC6819, January 2013, . Appendix A. Acknowledgements Caleb Baker participated in specifying the original set of "amr_values" values. Brian Campbell, William Denniss, and Nat Sakimura subsequently provided input on the set of "amr_values" values defined. Appendix B. Document History [[ to be removed by the RFC editor before publication as an RFC ]] -02 o Changed the identifier for risk-based authentication from "risk" to "rba", by popular acclaim. o Added "sc" (smart card). -01 Jones, et al. Expires February 22, 2016 [Page 11] Internet-Draft Authentication Method Reference Values August 2015 o Added the values "mca" (multiple-channel authentication), "risk" (risk-based authentication), and "user" (user presence test). o Added citations in the definitions of Windows integrated authentication, knowledge-based authentication, risk-based authentication, multiple-factor authentication, one-time password, and proof-of-possession. o Alphabetized the values. o Added Tony Nadalin as an author and added acknowledgements. -00 o Defined the IANA "Authentication Method Reference Values" registry. Authors' Addresses Michael B. Jones Microsoft Email: mbj@microsoft.com URI: http://self-issued.info/ Phil Hunt Oracle Email: phil.hunt@yahoo.com Anthony Nadalin Microsoft Email: tonynad@microsoft.com Jones, et al. Expires February 22, 2016 [Page 12]