Network Working Group L. Johansson
Internet-Draft NORDUNet
Intended status: Informational February 18, 2012
Expires: August 21, 2012
An IANA registry for Level of Assurance (LoA) Profiles
draft-johansson-loa-registry-04
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.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Name of Registry . . . . . . . . . . . . . . . . . . . . . . . 3
3. Registration Template . . . . . . . . . . . . . . . . . . . . . 4
3.1. Example Registration . . . . . . . . . . . . . . . . . . . 5
3.2. Note on the Example . . . . . . . . . . . . . . . . . . . . 6
4. Registration Policy . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Reviewer Expectations . . . . . . . . . . . . . . . . . . . 6
5. Registry Semantics . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. since -00 . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.2. since -01 . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.3. since -02 . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.4. since -03 . . . . . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
This document establishes an IANA registry for Level of Assurance
Profiles. One 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].
Such profiles are used in various protocols, including SAML 2.0 and
OpenID Connect. For SAML 2.0 the registry entries reference XML
schema definitions that fulfil the requirements of sstc.saml-
assurance-profile [OASIS.sstc.saml-assurance-profile]. For OpenID
Connect the registry consists a controlled vocabulary for the
iso29115level claim type. 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"._
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 explicitly 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
represent levels of assurance definitions without relying on their
SAML XML definitions. Use of the registry by protocols other than
SAML or OpenID Connect is encouraged.
1.1. 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].
2. Name of Registry
The name of the registry shall be "SAML 2.0 LoA Context Class", in
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plural "SAML LoA Context Classes". 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 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.
Note that it is not uncommon for a single XML Schema to contain
definitions of multiple URIs. In that case the registration MUST be
repeated for each URI. Both the name and the URI MUST uniquely
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 MUST fulfill the following ABNF:
label = ( ALPHA / DIGIT )
name = label 1*( label / "-" / "." / "_" )
The following ABNF productions represent reserved values and names
matching any of these productions MUST NOT be present in any
registration:
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".
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3.1. Example Registration
1. Name of requester: J. Random User
2. E-mail address of requester: jrandom@example.com
3. Organization of requester: Random Trust Frameworks LLP
4. Requested registration:
URI http://foo.example.com/assurance/loa1
Name foo-loa-1
SAML 2.0 Context Class Definition
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="http://foo.example.com/assurance/loa1"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="http://foo.example.com/assurance/loa1"
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/loa1
Defines Level 1 of FAF
</xs:documentation>
</xs:annotation>
<xs:complexType name="GoverningAgreementRefType">
<xs:complexContent>
<xs:restriction base="GoverningAgreementRefType">
<xs:attribute name="governingAgreementRef"
type="xs:anyURI"
fixed="http://foo.example.com/foo_assurance.pdf#section1"
use="required"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
</xs:redefine>
</xs:schema>
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3.2. Note on the Example
The example is borrowed from sstc.saml-assurance-profile
[OASIS.sstc.saml-assurance-profile]
4. Registration Policy
The registry is to be operated under the "Designated 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 unique within the registry.The initial pool of expert and the
review criteria are outlined below.
Registrations that reference multiple LoAs in a consistent set of
policies - for instance when a trust framework defines multiple
levels of assurance - the registered LoA Name and URIs SHOULD be
consistently named so as to be easily 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 bona fide
Level of Assurance Profiles while not presenting a very high bar for
entry. Expert reviewers SHOULD NOT place undue value in any
percieved or actual quality of the associated trust framework or
federation and SHOULD only exclude such registrations that in the
view of the experts do not represent bona fide attempts at defining
an LoA.
The designated experts are also expected to verify that the
registration is consistent and that the provided XML fulfills the
requirements of sstc.saml-assurance-profile
[OASIS.sstc.saml-assurance-profile].
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.
Consumers of the registry MUST NOT treat it as a complete list of all
existing LoA definitions and MUST provide a way for the user to
provide additional Level of Assurance Profile references by other
means. It is not expected that all LoA definitions will be contained
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in this registry.
The presense of an entry in the registy MUST NOT be taken to imply
any semantics beyond the review done by the expert reviewers 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
An implementor of MUST NOT treat the registry as a trust framework or
federation and MUST NOT make any assumptions about the properties of
any of the listed level of assurance URIs or their associated trust
frameworks or federations based on their presense in the IANA
registry.
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
was 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.
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9.2. since -01
o Allow for registration of short identifiers.
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
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.
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.
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Author's Address
Leif Johansson
NORDUNet
Tulegatan 11
Stockholm
Sweden
Email: leifj@nordu.net
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