OAuth Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track P. Hunt
Expires: September 18, 2016 Oracle
A. Nadalin
Microsoft
March 17, 2016
Authentication Method Reference Values
draft-ietf-oauth-amr-values-00
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.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 18, 2016.
Copyright Notice
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation and Conventions . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Authentication Method Reference Values . . . . . . . . . . . 3
3. Relationship to "acr" (Authentication Context Class
Reference) . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. Authentication Method Reference Values Registry . . . . . 6
6.1.1. Registration Template . . . . . . . . . . . . . . . . 7
6.1.2. Initial Registry Contents . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11
Appendix B. Document History . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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.
The set of "amr" values defined by this specification is not intended
to be an exhaustive set covering all use cases. Additional values
can and will be added to the registry by other specifications.
Rather, the values defined herein are an intentionally small set that
are already actually being used in practice.
For context, while the claim values registered pertain to
authentication, note that OAuth 2.0 [RFC6749] is designed for
resource authorization and cannot be used for authentication without
employing appropriate extensions, such as those defined by OpenID
Connect Core 1.0 [OpenID.Core]. The existence of the "amr" claim and
values for it should not be taken as encouragement to try to use
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OAuth 2.0 for authentication without employing extensions enabling
secure authentication to be performed.
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:
eye
Retina scan biometric
face
Facial recognition
fpt
Fingerprint biometric
geo
Use of geolocation information
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hwk
Proof-of-possession (PoP) of a hardware-secured key. See
Appendix C of [RFC4211] for a discussion on PoP.
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].
pin
Personal Identification Number or pattern (not restricted to
containing only numbers) that a user enters to unlock a key on the
device. This mechanism SHOULD have a way to deter an attacker
from obtaining the PIN by trying repeated guesses.
pwd
Password-based authentication
rba
Risk-based authentication [JECM]
sc
Smart card
sms
Confirmation using SMS message to the user at a registered number
swk
Proof-of-possession (PoP) of a software-secured key. See
Appendix C of [RFC4211] for a discussion on PoP.
tel
Confirmation by telephone call to the user at a registered number
user
User presence test
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vbm
Voice biometric
wia
Windows integrated authentication, as described in [MSDN]
3. 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, 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 satisfied.
In contrast, interactions using the "amr" claim make statements about
the particular authentication methods 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.
4. 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
identity provider. In some cases, this information may have privacy
implications.
5. 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 3, 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.
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6. IANA Considerations
6.1. 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 an Expert Review [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. To increase
potential interoperability, the experts are requested to encourage
registrants to provide the location of a publicly-accessible
specification defining the values being registered, so that their
intended usage can be more easily understood.
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
functionality, whether it is likely to be of general applicability or
whether it is useful only for a single application, whether the value
is actually being used, 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].
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6.1.1. 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.
6.1.2. 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 specification ]]
o Authentication Method Reference Name: "face"
o Authentication Method Reference Description: Facial recognition
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
o Authentication Method Reference Name: "fpt"
o Authentication Method Reference Description: Fingerprint biometric
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
o Authentication Method Reference Name: "geo"
o Authentication Method Reference Description: Geolocation
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
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o Authentication Method Reference Name: "hwk"
o Authentication Method Reference Description: Proof-of-possession
of a hardware-secured key
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
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 specification ]]
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 specification ]]
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 specification ]]
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 specification ]]
o Authentication Method Reference Name: "pin"
o Authentication Method Reference Description: Personal
Identification Number or pattern
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
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 specification ]]
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 specification ]]
o Authentication Method Reference Name: "sc"
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o Authentication Method Reference Description: Smart card
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
o Authentication Method Reference Name: "sms"
o Authentication Method Reference Description: Confirmation using
SMS
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
o Authentication Method Reference Name: "swk"
o Authentication Method Reference Description: Proof-of-possession
of a software-secured key
o Change Controller: IESG
o Specification Document(s): Section 2 of [[ this specification ]]
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 specification ]]
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 specification ]]
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 specification ]]
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 specification ]]
7. References
7.1. Normative References
[IANA.JWT.Claims]
IANA, "JSON Web Token Claims",
<http://www.iana.org/assignments/jwt>.
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[JECM] Williamson, G., "Enhanced Authentication In Online
Banking", Journal of Economic Crime Management 4.2: 18-19,
2006,
<http://utica.edu/academic/institutes/ecii/publications/
articles/51D6D996-90F2-F468-AC09C4E8071575AE.pdf>.
[JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
[MSDN] Microsoft, "Integrated Windows Authentication with
Negotiate", September 2011,
<http://blogs.msdn.com/b/benjaminperkins/
archive/2011/09/14/iis-integrated-windows-authentication-
with-negotiate.aspx>.
[NIST.800-63-2]
National Institute of Standards and Technology (NIST),
"Electronic Authentication Guideline", NIST Special
Publication 800-63-2, August 2013,
<http://nvlpubs.nist.gov/nistpubs/SpecialPublications/
NIST.SP.800-63-2.pdf>.
[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,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4211] Schaad, J., "Internet X.509 Public Key Infrastructure
Certificate Request Message Format (CRMF)", RFC 4211,
DOI 10.17487/RFC4211, September 2005,
<http://www.rfc-editor.org/info/rfc4211>.
[RFC4226] M'Raihi, D., Bellare, M., Hoornaert, F., Naccache, D., and
O. Ranen, "HOTP: An HMAC-Based One-Time Password
Algorithm", RFC 4226, DOI 10.17487/RFC4226, December 2005,
<http://www.rfc-editor.org/info/rfc4226>.
[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,
<http://www.rfc-editor.org/info/rfc5226>.
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[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,
<http://www.rfc-editor.org/info/rfc6238>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<http://www.rfc-editor.org/info/rfc6749>.
7.2. 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,
<http://www.rfc-editor.org/info/rfc6819>.
Appendix A. Acknowledgements
Caleb Baker participated in specifying the original set of "amr"
values. John Bradley, Brian Campbell, William Denniss, James Manger,
and Nat Sakimura provided reviews of the specification.
Appendix B. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-00
o Created the initial working group draft from draft-jones-oauth-
amr-values-05 with no normative changes.
Authors' Addresses
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
Phil Hunt
Oracle
Email: phil.hunt@yahoo.com
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Anthony Nadalin
Microsoft
Email: tonynad@microsoft.com
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