Internet DRAFT - draft-johansson-loa-registry
draft-johansson-loa-registry
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.
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This Internet-Draft will expire on November 5, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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publication of this document. Please review these documents
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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
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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.
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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 / "-" / "." / "_" )
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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/
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SAML 2.0 Authentication Context Class Definition
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="http://foo.example.com/assurance/loa-1"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="http://foo.example.com/assurance/loa-1"
finalDefault="extension"
blockDefault="substitution"
version="2.0">
<xs:redefine
schemaLocation="saml-schema-authn-context-loa-profile.xsd">
<xs:annotation>
<xs:documentation>
Class identifier:
http://foo.example.com/assurance/loa-1
Defines Level 1 of the Foo Assurance Framework
</xs:documentation>
</xs:annotation>
<xs:complexType name="GoverningAgreementRefType">
<xs:complexContent>
<xs:restriction base="GoverningAgreementRefType">
<xs:attribute name="governingAgreementRef"
type="xs:anyURI"
fixed="https://foo.example.com/assurance/"
use="required"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
</xs:redefine>
</xs:schema>
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
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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.
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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.
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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
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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
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