WS-I

SAML Token Profile Version 1.0

Working Group Draft

2004-11-06

This version:
http://www.ws-i.org/Profiles/SAMLTokenProfile-1.0-2004-11-06.html
Latest version:
http://www.ws-i.org/Profiles/SAMLTokenProfile-1.0.html
Editors:
Abbie Barbir, Nortel Networks
Martin Gudgin, Microsoft
Michael McIntosh, IBM
K. Scott Morrison, Layer 7
Administrative contact:
secretary@ws-i.org

Abstract

This document defines the WS-I SAML Token Profile 1.0, based on a non-proprietary Web services specification, along with clarifications and amendments to that specification which promote interoperability.

Status of this Document

This document is a Working Group Draft; it has been accepted by the Working Group as reflecting the current state of discussions. It is a work in progress, and should not be considered authoritative or final; other documents may supersede this document.

Notice

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Table of Contents

1. Introduction
1.1. Relationship to other Profiles
1.2. Notational Conventions
2. Scope of the Profile
2.1. Notational Conventions
2.2. Profile Identification and Versioning
3. Profile Conformance
3.1. Conformance Requirements
3.2. Conformance Targets
3.3. Conformance Scope
3.4. Claiming Conformance
3. SAML Token Profile
3.1. Requirements from SAML Token Profile
3.1.1. References to SAML assertions from SAML assertions prohibited
3.1.2. References to SAML assertions by KeyIdentifier
3.1.3. References to SAML assertions that are not in a message.
Appendix A: Referenced Specifications
Appendix B: Extensibility Points
Appendix C: Acknowledgements

1. Introduction

This document defines the WS-I SAML Token Profile 1.0 (hereafter, "Profile"), consisting of a non-proprietary Web services specification, along with clarifications to and amplifications of that specification which promote interoperability.

Section 1 introduces the Profile.

Section 2, "Scope of the Profile," delimits the areas where the Profile improves interoperability.

Section 3, "Profile Conformance," explains what it means to be conformant to the Profile.

Each subsequent section addresses a component of the Profile, and consists of two parts; an overview detailing the component specifications and their extensibility points, followed by subsections that address individual parts of the component specifications. Note that there is no relationship between the section numbers in this document and those in the referenced specifications.

1.1 Relationship to other Profiles

This Profile adds an additional security token type for use with Basic Security Profile 1.0.

1.2 Notational Conventions

Extensibility points in underlying specifications (see "Conformance Scope") are presented in a similar manner:

Ennnn Extensibility Point Name - Description.

Non-normative security considerations are presented in a similar manner:

Cnnnn Statement text here.

Some statements clarify the referenced specification(s), but do not place additional constraints upon implementations. For convenience, clarifications are annotated by a superscript letter 'c' on a blue background: C

2. Scope of the Profile

The scope of the Profile delineates the technologies that it addresses; in other words, the Profile only attempts to improve interoperability within its own scope. Initially, the Profile's scope is bounded by the specifications referenced by it; for a complete list of the Profile's referenced specifications, see Appendix I.

The Profile's scope is further refined by extensibility points. Referenced specifications often provide extension mechanisms and unspecified or open-ended configuration parameters. When identified as an extensibility point, such a mechanism or parameter is outside the scope of the Profile, and its use is not subject to claims of conformance to this Profile.

Because the use of extensibility points may impair interoperability, their use should be negotiated or documented in some fashion by the parties to a Web service. For example, this could take the form of an out-of-band agreement.

Note that the Profile may still place requirements on the use of an extensibility point, without constraining its range. Also, specific uses of extensibility points may be further restricted by other profiles, to improve their interoperability when used in conjunction with the Profile.

For a complete list of the Profile's extensibility points, see Appendix II.

2.1 Notational Conventions

The keywords "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.

Normative statements of requirements in the Profile (i.e., those impacting conformance, as outlined in "Conformance Requirements") are presented in the following manner:

RnnnnStatement text here.

where "nnnn" is replaced by a number that is unique among the requirements in the Profile, thereby forming a unique requirement identifier.

Requirement identifiers can be considered to be namespace qualified, in such a way as to be compatible with QNames from Namespaces in XML. If there is no explicit namespace prefix on a requirement's identifier (e.g., "R9999" as opposed to "bp10:R9999"), it should be interpreted as being in the namespace identified by the conformance URI of the document section it occurs in. If it is qualified, the prefix should be interpreted according to the namespace mappings in effect, as documented below.

Some requirements clarify the referenced specification(s), but do not place additional constraints upon implementations. For convenience, clarifications are annotated in the following manner: C

Some requirements are derived from ongoing standardization work on the referenced specification(s). For convenience, such forward-derived statements are annotated in the following manner: xxxx, where "xxxx" is an identifier for the specification (e.g., "WSDL20" for WSDL Version 2.0). Note that because such work was not complete when this document was publiished, the specification that the requirement is derived from may change; this information is included only as a convenience to implementers.

This specification uses a number of namespace prefixes throughout; their associated URIs are listed below. Note that the choice of any namespace prefix is arbitrary and not semantically significant.

2.2 Profile Identification and Versioning

This document is identified by a name (in this case, SAML Token Profile) and a version number (here, 1.0). Together, they identify a particular profile instance.

Version numbers are composed of a major and minor portion, in the form "major.minor". They can be used to determine the precedence of a profile instance; a higher version number (considering both the major and minor components) indicates that an instance is more recent, and therefore supersedes earlier instances.

Instances of profiles with the same name (e.g., "Example Profile 1.1" and "Example Profile 5.0") address interoperability problems in the same general scope (although some developments may require the exact scope of a profile to change between instances).

One can also use this information to determine whether two instances of a profile are backwards-compatible; that is, whether one can assume that conformance to an earlier profile instance implies conformance to a later one. Profile instances with the same name and major version number (e.g., "Example Profile 1.0" and "Example Profile 1.1") MAY be considered compatible. Note that this does not imply anything about compatibility in the other direction; that is, one cannot assume that conformance with a later profile instance implies conformance to an earlier one.

3 Profile Conformance

Conformance to the Profile is defined by adherence to the set of requirements defined for a specific target, within the scope of the Profile. This section explains these terms and describes how conformance is defined and used.

3.1 Conformance Requirements

Requirements state the criteria for conformance to the Profile. They typically refer to an existing specification and embody refinements, amplifications, interpretations and clarifications to it in order to improve interoperability. All requirements in the Profile are considered normative, and those in the specifications it references that are in-scope (see "Conformance Scope") should likewise be considered normative. When requirements in the Profile and its referenced specifications contradict each other, the Profile's requirements take precedence for purposes of Profile conformance.

Requirement levels, using RFC2119 language (e.g., MUST, MAY, SHOULD) indicate the nature of the requirement and its impact on conformance. Each requirement is individually identified (e.g., R9999) for convenience.

For example;

R9999 WIDGETs SHOULD be round in shape.

This requirement is identified by "R9999", applies to the target WIDGET (see below), and places a conditional requirement upon widgets; i.e., although this requirement must be met to maintain conformance in most cases, there are some situations where there may be valid reasons for it not being met (which are explained in the requirement itself, or in its accompanying text).

Each requirement statement contains exactly one requirement level keyword (e.g., "MUST") and one conformance target keyword (e.g., "MESSAGE"). Additional text may be included to illuminate a requirement or group of requirements (e.g., rationale and examples); however, prose surrounding requirement statements must not be considered in determining conformance.

Definitions of terms in the Profile are considered authoritative for the purposes of determining conformance.

None of the requirements in the Profile, regardless of their conformance level, should be interpreted as limiting the ability of an otherwise conforming implementation to apply security countermeasures in response to a real or perceived threat (e.g., a denial of service attack).

3.2 Conformance Targets

Conformance targets identify what artifacts (e.g., SOAP message, WSDL description, UDDI registry data) or parties (e.g., SOAP processor, end user) requirements apply to.

This allows for the definition of conformance in different contexts, to assure unambiguous interpretation of the applicability of requirements, and to allow conformance testing of artifacts (e.g., SOAP messages and WSDL descriptions) and the behavior of various parties to a Web service (e.g., clients and service instances).

Requirements' conformance targets are physical artifacts wherever possible, to simplify testing and avoid ambiguity.

The following conformance targets are used in the Profile:

3.3 Conformance Scope

The scope of the Profile delineates the technologies that it addresses; in other words, the Profile only attempts to improve interoperability within its own scope. Generally, the Profile's scope is bounded by the specifications referenced by it.

The Profile's scope is further refined by extensibility points. Referenced specifications often provide extension mechanisms and unspecified or open-ended configuration parameters; when identified in the Profile as an extensibility point, such a mechanism or parameter is outside the scope of the Profile, and its use or non-use is not relevant to conformance.

Note that the Profile may still place requirements on the use of an extensibility point. Also, specific uses of extensibility points may be further restricted by other profiles, to improve interoperability when used in conjunction with the Profile.

Because the use of extensibility points may impair interoperability, their use should be negotiated or documented in some fashion by the parties to a Web service; for example, this could take the form of an out-of-band agreement.

The Profile's scope is defined by the referenced specifications in Appendix A, as refined by the extensibility points in Appendix B.

3.4 Claiming Conformance

Claims of conformance to the Profile can be made using the following mechanisms, as described in Conformance Claim Attachment Mechanisms, when the applicable Profile requirements associated with the listed targets have been met:

The CCAM URI may change before final publication.

The conformance claim URI for this Profile is "http://ws-i.org/profiles/basic-security/saml-token/1.0".

3. SAML Token Profile

This section of the Profile incorporates the following specifications by reference, and defines extensibility points within them:

3.1 Requirements from SAML Token Profile

The following specifications (or sections thereof) are referred to in this section of the Profile:

Web Services Security: SAML Token Profile contains various statements containing the RFC2119 'MUST' keyword. This Profile restates some of those statements:

3.1.1 References to SAML assertions from SAML assertions prohibited

This requirement rules out the possibility of a SAML assertion refering to itself, an undesirable occurence as it essentially makes the assertion self certifying. In addition references to another SAML assertion is also ruled out, this is undesirable as SAML does not have a transative trust model.

R6601 A ds:KeyInfo element within a saml:SubjectConfirmation element in a SECURE_ENVELOPE MUST NOT contain a reference to a SAML assertion. C

For example,

INCORRECT: 

<!-- This example is incorrect because the ds:KeyInfo in the SAML assertion contains a reference to another such assertion thus conflicting with R6601 -->
<wsse:Security xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd' 
               xmlns:wsu='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd' 
               xmlns:xenc='http://www.w3.org/2001/04/xmlenc#' 
               xmlns:ds='http://www.w3.org/2000/09/xmldsig#' >
  <saml:Assertion xmlns:saml='urn:oasis:names:tc:SAML:1.0:assertion' 
                  MajorVersion='1' MinorVersion='1' 
                  AssertionID='uuid:006ab385-35e0-41b1-b0f5-ccef5090c1b0'
                  Issuer='http://example.org/issuer' IssueInstant='2004-11-04T21:01:50Z' >
    . . .
    <saml:AuthenticationStatement AuthenticationMethod='urn:oasis:names:tc:SAML:1.0:am:password' AuthenticationInstant='2004-11-04T21:01:50Z' >
      <saml:Subject>
        . . .
        <saml:SubjectConfirmation>
          . . .
          <ds:KeyInfo xmlns:ds='http://www.w3.org/2000/09/xmldsig#' >
            <wsse:SecurityTokenReference>
              <wsse:Reference URI='uuid:a9afffbe-a0fb-4789-8b54-299782c3c0ac' 
                              ValueType='http://docs.oasis-open.org/wss/2004/XX/oasis-2004XX-wss-saml-token-profile-1.0#SAMLAssertionID' />
            </wsse:SecurityTokenReference>
          </ds:KeyInfo>
        </saml:SubjectConfirmation>
      </saml:Subject>
    </saml:AuthenticationStatement>
	. . .
  </saml:Assertion>
</wsse:Security>

3.1.2 References to SAML assertions by KeyIdentifier

These requirements restate various statements from the base specification related to references to SAML assertions that use wsse:KeyIdentifiers.

R6602 In a SECURE_ENVELOPE any wsse:SecurityTokenReference/wsse:KeyIdentifier element that references a SAML assertion MUST carry a ValueType attribute C

R6603 In a SECURE_ENVELOPE the ValueType attribute on a wsse:SecurityTokenReference/wsse:KeyIdentifier element that reference a SAML assertion MUST have a value of "http://docs.oasis-open.org/wss/2004/XX/oasis-2004XX-wss-saml-token-profile-1.0#SAMLAssertionID" C

R6604 In a SECURE_ENVELOPE any wsse:SecurityTokenReference/wsse:KeyIdentifier element that references a SAML assertion MUST NOT carry an EncodingType attribute. C

R6605 In a SECURE_ENVELOPE any wsse:SecurityTokenReference/wsse:KeyIdentifier element that references a SAML assertion MUST encode the value of the key identifier as as the type xs:string. C

For example,

CORRECT: 

<wsse:SecurityTokenReference xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd'>
  <wsse:KeyIdentifier ValueType='http://docs.oasis-open.org/wss/2004/XX/oasis-2004XX-wss-saml-token-profile-1.0#SAMLAssertionID' >
  uuid:006ab385-35e0-41b1-b0f5-ccef5090c1b0
  </wsse:KeyIdentifier>
</wsse:SecurityTokenReference>

INCORRECT: 

<!-- This example is incorrect because the wsse:KeyIdentifier element is missing a ValueType attribute thus conflicting with R6602 -->
<wsse:SecurityTokenReference xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd'>
  <wsse:KeyIdentifier>uuid:006ab385-35e0-41b1-b0f5-ccef5090c1b0</wsse:KeyIdentifier>
</wsse:SecurityTokenReference>

INCORRECT: 

<!-- This example is incorrect because the wsse:KeyIdentifier element has an incorrect value for the ValueType attribute thus conflicting with R6603 -->
<wsse:SecurityTokenReference xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd'>
  <wsse:KeyIdentifier ValueType='http://docs.oasis-open.org/wss/2004/XX/oasis-2004XX-wss-saml-token-profile-1.0#SAML'>
  uuid:006ab385-35e0-41b1-b0f5-ccef5090c1b0
  </wsse:KeyIdentifier>
</wsse:SecurityTokenReference>

INCORRECT: 

<!-- This example is incorrect because the wsse:KeyIdentifier has an EncodingType attribute thus conflicting with R6604 -->
<wsse:SecurityTokenReference xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd'>
  <wsse:KeyIdentifier ValueType='http://docs.oasis-open.org/wss/2004/XX/oasis-2004XX-wss-saml-token-profile-1.0#SAMLAssertionID'
                      EncodingType='xs:string' >
  uuid:006ab385-35e0-41b1-b0f5-ccef5090c1b0
  </wsse:KeyIdentifier>
</wsse:SecurityTokenReference>

3.1.3 References to SAML assertions that are not in a message.

These requirements restate various statements from the base specification related to references to SAML assertions that are outside a SECURE_ENVELOPE.

R6606 In a SECURE_ENVELOPE any wsse:SecurityTokenReference that refences a SAML assertion by wsse:KeyIdentifier where the referenced SAML assertion is NOT present in the SECURE_ENVELOPE MUST contain a saml:AuthorityBinding element. C

R6607 The value of any wsse:SecurityTokenReference/saml:AuthorityBinding/@AuthorityKind attribute in a SECURE_ENVELOPE MUST be samlp:AssertionIdReference. C

R6608 In a SECURE_ENVELOPE any wsse:SecurityTokenReference that refences a SAML assertion by wsse:KeyIdentifier where the referenced SAML assertion is present in the SECURE_ENVELOPE MUST NOT contain saml:AuthorityBinding element. C

Appendix A: Referenced Specifications

The following specifications' requirements are incorporated into the Profile by reference, except where superseded by the Profile:

Appendix B: Extensibility Points

This section identifies extensibility points, as defined in "Scope of the Profile," for the Profile's component specifications.

These mechanisms are out of the scope of the Profile; their use may affect interoperability, and may require private agreement between the parties to a Web service.

Appendix C: Acknowledgements

This document is the work of the WS-I Basic Security Profiles Working Group, whose members have included:

Steve Anderson (OpenNetwork), Paula Austel (IBM), Siddharth Bajaj (Verisign), Abbie Barbir (Nortel Networks), David Baum (Kantega AS), Randy Bias (Grand Central Communications), Tim Bond (webMethods Inc.), Heidi Buelow (Quovadx), David Burdett (Commerce One, Inc.), Ted Burghart (Hitachi, Ltd.) Symon Chang (Commerce One, Inc.), Richard Chennault, (Kaiser Permanente), Dipak Chopra (SAP AG), Jamie Clark (OASIS), Edward Cobb (BEA Systems Inc.), David Cohen (Merrill Lynch), Brett Cooper, (Accenture), Ugo Corda (SeeBeyond Technology), Paul Cotton (Microsoft Corporation), Suresh Damodaran, (Rosettanet), Mark Davis (Sarvega Inc.), Alex Deacon (Verisign), Thomas DiMartini (ContentGuard), Blake Dournaee (Sarvega Inc.), Rob Drew (Charlse Schwab), Gregory Elkins (Reed Elsevier), Mark Ericson (Mindreef), Jon Oyvind Eriksen (Kantega AS), Chris Ferris (IBM), Bob Freund, (Hitachi), Edwin Goei (Sun Microsystems), Grant Goodale (Reactivity Inc.), Marc Goodner (SAP AG), Phil Goodwin (Sun Microsystems), Marc Graveline (Cognos, Inc.), Eric Gravengaard (Reactivity Inc.), Thomas Gross (IBM), Martin Gudgin (Microsoft Corporation), Marc Hadley (Sun Microsystems), Mark Hapner (Sun Microsystems), Nathan Harris (Kaiser Permanente), Bret Hartman (Datapower Technology, Inc.), Frederick Hirsch (Nokia), Jason Hogg (Microsoft Corporation), Maryann Hondo (IBM), Lawrence Hsiung (Quovadx), Tony Huber (Commerce Quest), Jim Hughes (Hewlett-Packard), Michael Hui (Computer Associates), Brian Jackson (Avanade Inc.), Steve Jenisch (SAS Institute), Erik Johnson (Epicor), Chris Kaler (Microsoft Corporation), Anish Karmarkar (Oracle Corporation), Dana Kaufman, (Forum Systems), Manveen Kaur (Sun Microsystems), Slava Kavsan (RSA Security), Paul Knight (Nortel Networks), Chris Kurt (Microsoft Corporation), Kelvin Lawrence (IBM), Hal Lockhart (BEA Systems), Brad Lund (Intel Corporation), Jim Luth (OPC Foundation), Paul Madsen (Entrust Inc.), Eve Maler (Sun Microsystems), Skip Marler (Parasoft), Axl Mattheus (Sun Microsystems), Michael McIntosh (IBM), Craig Milhiser, (Ascential), Chris Miller (Accenture), Dale Moberg (Cyclone Commerce), Ron Monzillo (Sun Microsystems), Scott Morrison, (Layer 7) Tim Moses (Entrust Inc.), Tony Nadalin (IBM), Nataraj Nagaratnam (IBM), Andrew Nash (RSA Security), Hsin Ning (Bestning Technologies), Eisaku Nishiyama (Hitachi, Ltd.), Mark Nottingham (BEA Systems Inc.), TJ Pannu (ContentGuard Inc.), Martine Pean (Quovadx), Robert Philpott (RSA Security), Dave Prout (BT), Joe Pruitt (F5 Networks Inc.), Eric Rejkovic (Oracle Corporation), Matt Cecupito (Accenture), Jason Rouault (Hewlett-Packard), Rich Salz (Datapower Technology Inc.), Matt Sanchez (Webify Solutions Inc. ), Jerry Schwarz (Oracle Corporation), Senthil Sengodan (Nokia), Shawn Sharp (Cyclone Commerce), Aslak Siira (F5 Networks Inc.), David Solo (Citigroup, Inc. ), Davanum Srinivas (Computer Associates), Raghavan Srinivas (Sun Microsystems), John Stanton (Defense Information Systems Agency), Andrew Stone (Accenture), Julie Surer (MITRE), Wes Swenson (Forum Systems), Dino Vitale (Citigroup, Inc.), Jonathan Wenocur (Datapower Technology, Inc.), Pete Wenzel (SeeBeyond Technology), Ian White (Micro Focus)