Network Working Group L. Johansson Internet-Draft NORDUNet Intended status: Informational May 4, 2012 Expires: November 5, 2012 An IANA registry for Level of Assurance (LoA) Profiles draft-johansson-loa-registry-06 Abstract This document establishes an IANA registry for Level of Assurance (LoA) Profiles. The registry is intended to be used as an aid to discovering such LoA definitions in protocols that use an LoA concept, including SAML 2.0 and OpenID Connect. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 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 November 5, 2012. Copyright Notice Copyright (c) 2012 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents Johansson Expires November 5, 2012 [Page 1] Internet-Draft LoA Registry May 2012 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 2. Name of Registry . . . . . . . . . . . . . . . . . . . . . . . 4 3. Registration Template . . . . . . . . . . . . . . . . . . . . 4 3.1. Example Registration . . . . . . . . . . . . . . . . . . . 5 3.2. Note on the Example . . . . . . . . . . . . . . . . . . . 6 4. Registration Policy . . . . . . . . . . . . . . . . . . . . . 6 4.1. Reviewer Expectations . . . . . . . . . . . . . . . . . . 7 5. Registry Semantics . . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 9.1. since -00 . . . . . . . . . . . . . . . . . . . . . . . . 8 9.2. since -01 . . . . . . . . . . . . . . . . . . . . . . . . 8 9.3. since -02 . . . . . . . . . . . . . . . . . . . . . . . . 9 9.4. since -03 . . . . . . . . . . . . . . . . . . . . . . . . 9 9.5. since -04 . . . . . . . . . . . . . . . . . . . . . . . . 9 9.6. since -05 . . . . . . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Johansson Expires November 5, 2012 [Page 2] Internet-Draft LoA Registry May 2012 1. Introduction This document establishes an IANA registry for Level of Assurance Profiles. Quoting from sstc.saml-assurance-profile [OASIS.sstc.saml-assurance-profile] we find the following definition of the concept of 'level of assurance': _Many existing (and potential) SAML federation deployments have adopted a "levels of assurance" (or LOA) model for categorizing the wide variety of authentication methods into a small number of levels, typically based on some notion of the strength of the authentication. Federation members (service providers or "relying parties") then decide which level of assurance is required to access specific protected resources, based on some assessment of "value" or "risk"._ Another definition of a 'level of assurance' is given in RFC4949 [RFC4949] which also identifies the roots of such profiles in the NIST special publication series, in particular SP 800-63 [SP63]. Level of Assurance profiles are used in various protocols, including the Security Assertion Markup Language (SAML) version 2.0 and OpenID Connect. Several so called trust frameworks and identity federations now exist, some of which define one or more Level of Assurance (LoA). The purpose of this specification is to create an IANA registry where such LoA definitions can be discovered. While the quote above references SAML the notion of a "level of assurance" has gained wide- spread acceptance and should be treated as a protocol-independent concept. The proposed IANA registry attempts to reflects this. Although the registry will contain URIs that reference SAML Authentication Context Profiles other protocols may use such URIs to identify levels of assurance definitions without relying on or transmitting their SAML XML definitions. Use of the registry by protocols other than SAML is encouraged. For instance OpenID Connect defines the standard claim 'acr' as a identifier that may reference a SAML Authentication Context Class even though OpenID Connect is not itself based on XML or SAML. Protocol designers who want to reference the registry should be aware that registered LoAs may depend on assumptions that do not carry over to all protocols and that such assumptions may vary among the protocols for which the LoAs were originally registered. Johansson Expires November 5, 2012 [Page 3] Internet-Draft LoA Registry May 2012 2. Name of Registry The name of the registry shall be "Level of Assurance Profile", in plural "Level of Assurance Profiles". The term LoA is an abbreviation of Level of Assurance. 3. Registration Template The following information must be provided with each registration: URI: A URI referencing a Level of Assurance Profile. This is the registry key. Context Class: A valid XML schema definition for the SAML 2.0 LoA Context Class fulfilling the requirements of sstc.saml-assurance- profile [OASIS.sstc.saml-assurance-profile]. The registry key (the URI) is the unique identifier for the Context Class. Name: A string uniquely and unambiguously identifying the LoA for use in protocols where URIs are not appropriate. Informational URL: A URL containing auxilliary information. This URL must minimally reference contact information for the administrative authority of the level of assurance definition and must use either the http or https schemes. Note that it is possible for a single SAML Authentication Context Class to contain definitions of multiple URIs. In that case a separate registration is to be used for each URI. Both the name and the URI are to uniquely and unambigously identify the LoA. The name is meant to be used in protocols where URIs are not appropriate. In addition the requester is expected to provide basic contact information and the name of the organization on behalf of which the LoA definition is registered. The Name is defined by the following ABNF (as defined in RFC5234 [RFC5234]): label = ( ALPHA / DIGIT ) name = label 1*( label / "-" / "." / "_" ) Johansson Expires November 5, 2012 [Page 4] Internet-Draft LoA Registry May 2012 The elements defined by the following ABNF productions represent a set of reserved values for the Name element and are not to be registered: reserved = loa / al / num loa = ( "l" / "L" ) ( "o" / "O" ) ( "a" / "A") *DIGIT al = ( "a" / "A") ( "l" / "L") *DIGIT num = *DIGIT The reason for excluding these productions is a desire to avoid a race to register overly generic LoA profiles under names like "AL1" or "LOA2". 3.1. Example Registration 1. Name of requester: J. Random User 2. E-mail address of requester: jrandom@example.com 3. Organization of requester: Example Trust Frameworks LLP 4. Requested registration: URI http://foo.example.com/assurance/loa-1 Name foo-loa-1 Information URL https://foo.example.com/assurance/ Johansson Expires November 5, 2012 [Page 5] Internet-Draft LoA Registry May 2012 SAML 2.0 Authentication Context Class Definition Class identifier: http://foo.example.com/assurance/loa-1 Defines Level 1 of the Foo Assurance Framework 3.2. Note on the Example The example is borrowed (slightly modified) from sstc.saml-assurance- profile [OASIS.sstc.saml-assurance-profile]. The example should not be registered. 4. Registration Policy The registry is to be operated under the "Expert Review" policy from RFC5226 [RFC5226] employing a pool of experts. IANA is kindly asked to do rough randomized load-balancing among the experts and also do an initial review of each submission to ensure that the name is and URI are unique within the registry. The review criteria are outlined below. Registrations that reference multiple LoAs in a consistent set of Johansson Expires November 5, 2012 [Page 6] Internet-Draft LoA Registry May 2012 policies - for instance when a trust framework defines multiple levels of assurance - the registered LoA Name and URIs should be consistently named so that they identified as belonging to the same set of registrations. For instance fruitLoA1,fruitLoA2 and fruitLoA3 is preferred over apple,pear and banana when these Names refer to a single set of policies defining 3 LoAs. 4.1. Reviewer Expectations The expectation of the IANA LoA Registry is that it contain registrations of bona fide Level of Assurance Profiles while not presenting a very high bar for entry. Expert reviewers are expected to verify that: o the registration is consistent and that the provided XML fulfills the requirements of sstc.saml-assurance-profile [OASIS.sstc.saml-assurance-profile]. o the Name element is clearly associated with the registered LoA Profile and is not a reserved value. o the URI and Name elements are not already registered. o the Information URL can be expected to be stable and permanent. Note that multiple registrations may share a common Informational URL. The reviewers should exclude registrations where the Name does not unambiguously identify the LoA definition or where the Name is a simple variation on one of the reserved names. Expert reviewers are expected to allow registrations made in good faith that fulfil these requirements. 5. Registry Semantics The intended use for this registry is to serve as a basis for discovery of LoA definitions that might for instance be used by protocol-specific (eg SAML 2.0 or OpenID Connect) management tools. Note that consumers of the registry, being implementations of [OASIS.sstc.saml-ass], are expected to allow configuration of LoA URIs at system deploy-time. If multiple sources of LOA URIs are permitted in addition to the registry (eg manual input) then it is important to avoid collisions with URIs found in the registry. Johansson Expires November 5, 2012 [Page 7] Internet-Draft LoA Registry May 2012 The presence of an entry in the registry does not imply any semantic or quality beyond that which results from the review done by the expert reviewer as part of the registration process. 6. IANA Considerations This document sets up a registry with IANA making the whole document a set of considerations for IANA. 7. Security Considerations The registry is not a federation or trust framework. Consumers of the registry are strongly advised to review the information about an LoA before relying on it. 8. Acknowledgements RL 'Bob' Morgan, Scott Cantor, Lucy Lynch and John Bradley were involved in the initial discussions around this idea and contributed to the semantics of the registry. The various versions of the draft were socialized in the Kantara Federation Interoperability WG and in other parts of the identity community. 9. Changes Note to the RFC editor: This section should be removed before publication. 9.1. since -00 o Clarified the security considerations wrt the status of the IANA registry. o Text in the introduction that explains that the registry can be used by other protocols than SAML and that this is encouraged. 9.2. since -01 o Allow for registration of short identifiers. Johansson Expires November 5, 2012 [Page 8] Internet-Draft LoA Registry May 2012 9.3. since -02 o Make the text less explicitly dependent on SAML. o Include OpenID Connect reference. o Corrected the SSTC reference o Reserve numeric-only LoA names (eg '1') 9.4. since -03 o comments from PROTO writeup, AD and document shepherd o remove initial list of reviewers - it will be decided by IESG o example registration 9.5. since -04 o ABNF fixes o example registration o policy for consistent naming across multiple related registrations o minor nits 9.6. since -05 o clarified introduction by re-arranging paragraphs o removed RFC2119-language o clarified security considerations section o clarified reviewer expectations o corrected the example o corrected reference to IANA Expert Review policy o included ABNF reference o expectations on Information URI stability o limit the allowed Information URI scheme Johansson Expires November 5, 2012 [Page 9] Internet-Draft LoA Registry May 2012 o various nits 10. References 10.1. Normative References [OASIS.sstc.saml-assurance-profile] Morgan, RL., Madsen, PM., and S. Cantor, "SAML V2.0 Identity Assurance Profiles Version 1.0", November 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. 10.2. Informative References [RFC4949] Shirey, R., "Internet Security Glossary, Version 2", RFC 4949, August 2007. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [SP63] NIST, "Electronic Authentication Guideline, NIST Special Publication 800-63", June 2004. Author's Address Leif Johansson NORDUNet Tulegatan 11 Stockholm Sweden Email: leifj@nordu.net Johansson Expires November 5, 2012 [Page 10]