Geopriv C. Guenther Internet-Draft Siemens Expires: January 14, 2006 July 13, 2005 SAML in Authorization Policies draft-guenther-geopriv-saml-policy-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 14, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Rules of an authorization policy prescribe under which conditions an entity or subject has which permissions. Existing policies support identity-based authorization by matching the authenticated identity of the entity requesting access to a resource with the available policies. This document is about formulating policy rules that express conditions with respect to SAML assertions, thereby supporting non-identity-based authorization and anonymity. Guenther Expires January 14, 2006 [Page 1] Internet-Draft SAML in Authorization Policies July 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Basic Scenario . . . . . . . . . . . . . . . . . . . . . . . 5 4. SAML Condition Example . . . . . . . . . . . . . . . . . . . 6 5. SAML Condition Schema . . . . . . . . . . . . . . . . . . . 9 6. Common Policy Schema . . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16 9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 17 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 10.1 Normative References . . . . . . . . . . . . . . . . . . 18 10.2 Informative References . . . . . . . . . . . . . . . . . 18 Author's Address . . . . . . . . . . . . . . . . . . . . . . 18 Intellectual Property and Copyright Statements . . . . . . . 19 Guenther Expires January 14, 2006 [Page 2] Internet-Draft SAML in Authorization Policies July 2005 1. Introduction The Security Assertion Markup Language, see [SAMLCore], is an XML sublanguage for exchanging security information. It is suitable for expressing assertions concerning previously performed authentication procedures and authorization decisions. For example, a SAML assertion can be used by the assertion issuer to assure that the assertion subject (e.g., a person, a network entity, ...) has been authenticated by means of a specific authentication method. A recipient of such an assertion - if it has trust in the assertion issuer and the integrity of the assertion - can then base its authorization decisions on this assertion. This document is about defining an extension to the Common Policy markup language, see [I-D.ietf-geopriv-common-policy], that allows to express conditions with respect to statements contained in SAML assertions. It shall be possible to express authorization policy rules of the following fashion: If the SAML assertion has been issued by the assertion issuer A and if the assertion assures that the assertion subject S has been authenticated by means of the authenticated method M, then S is permitted to ... . Guenther Expires January 14, 2006 [Page 3] Internet-Draft SAML in Authorization Policies July 2005 2. Terminology 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]. Guenther Expires January 14, 2006 [Page 4] Internet-Draft SAML in Authorization Policies July 2005 3. Basic Scenario Figure 1 depicts a basic scenario in the scope of this document: a Subject S wishes to have access to a certain resource (e.g., location information of a particular entity). After a successful authentication protocol execution between S and the Asserting Party (AP), see step 1, the AP issues a SAML assertion (step 2), which asserts that S has been authenticated by AP using method M and is associated with a certain set of attributes. +-------------+ 1: Authentication +------------+ | |<----------------->| Asserting | | Subject (S) | | Party | | |<------------------| (AP) | +-------------+ 2: SAML Assertion +------------+ | | 3:| Service Request | + Assertion v +-------------+ +------------+ | Relying | 4: Policy | Policy | | Party |<------------------| Server | | (RP) | | (PS) | +-------------+ +------------+ Figure 1: Basic Scenario After receipt of the assertion, the Relying Party (RP) can base its resource access authorization decision on this assertion. The authorization policy governing access to the requested resource is stored at the Policy Server (PS). Thanks to the language elements introduced in this document, this policy can contain rules whose conditions parts express properties that the SAML assertion must meet in order to make the rule match. Guenther Expires January 14, 2006 [Page 5] Internet-Draft SAML in Authorization Policies July 2005 4. SAML Condition Example Each policy rule of the Common Policy markup language [I-D.ietf- geopriv-common-policy] consists of a , an and a element (all of which are optional elements). The Common Policy XML schema defines the element in such a way that it allows for any child elements that belong to XML namespaces different from the common policy namespace. This document defines a new XML element, namely, the element, whose purpose is to be used as such a child element of the common policy element. This paragraph provides an example of an XML document valid with respect to the SAML Condition schema (as shown in Section 5) and the Common Policy schema (as listed in Section 6). 2005-08-02T17:00:00-05:00 2005-08-04T19:00:00-05:00 idp.com bob@example.com urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport Guenther Expires January 14, 2006 [Page 6] Internet-Draft SAML in Authorization Policies July 2005 urn:oasis:names:tc:SAML:2.0:ac:classes:X509 The rule set in this example consists of one rule only. The part of the rule consists of a condition (defined by the Common Policy schema) and a (defined by this document in Section 5). The element specifies the time period during which the rule is applicable. The element as shown above evaluates to true if and only if the SAML assertion presented to the Relying Party satisfies the following properties: 1) The issuer of the SAML assertion is idp.com. 2) The subject of the SAML assertion is bob@example.com. 3) The authentication context class referenced in the SAML assertion is PasswordProtectedTransport (i.e., the subject of the assertion has authenticated to the Asserting Party through the presentation of a password over a protected session) or X509 (i.e., the subject of the assertion has authenticated to the Asserting Party by means of a digital signature where the key was validated as part of a X.509 public key infrastructure). To be more precisely, the SAML assertion presented to the Relying Party has to satisfy the following properties to make the element evaluate to true: Guenther Expires January 14, 2006 [Page 7] Internet-Draft SAML in Authorization Policies July 2005 1) The content of the element of the SAML assertion must equal the string "idp.com". 2) The SAML assertion must contain a child element (which is optional by the SAML assertion schema), and this element must contain a element whose content equals the string "bob@example.com". 3) The SAML assertion must contain an element with an child element that possesses an child element whose content is either urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport or urn:oasis:names:tc:SAML:2.0:ac:classes:X509. The complete list of Authentication Context types defined by SAML can be found in [SAMLAuthnContext]. Guenther Expires January 14, 2006 [Page 8] Internet-Draft SAML in Authorization Policies July 2005 5. SAML Condition Schema Guenther Expires January 14, 2006 [Page 9] Internet-Draft SAML in Authorization Policies July 2005 Guenther Expires January 14, 2006 [Page 10] Internet-Draft SAML in Authorization Policies July 2005 6. Common Policy Schema Just for the sake of completeness, this section contains that version of the Common Policy XML schema that defines - along with the schema specified in Section 5 - the XML language to which the example in Section 4 belongs. Guenther Expires January 14, 2006 [Page 11] Internet-Draft SAML in Authorization Policies July 2005 Guenther Expires January 14, 2006 [Page 12] Internet-Draft SAML in Authorization Policies July 2005 Guenther Expires January 14, 2006 [Page 13] Internet-Draft SAML in Authorization Policies July 2005 Guenther Expires January 14, 2006 [Page 14] Internet-Draft SAML in Authorization Policies July 2005 7. Security Considerations [tbd] Guenther Expires January 14, 2006 [Page 15] Internet-Draft SAML in Authorization Policies July 2005 8. IANA Considerations [tbd] Guenther Expires January 14, 2006 [Page 16] Internet-Draft SAML in Authorization Policies July 2005 9. Open Issues 1) SAML assertions with authorization decision statements. 2) SAML assertions with attribute statements. 3) Alignment with Common Policy markup language. 4) Security Considerations. 5) IANA considerations. Guenther Expires January 14, 2006 [Page 17] Internet-Draft SAML in Authorization Policies July 2005 10. References 10.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [SAMLAuthnContext] OASIS, "Authentication Context for the OASIS Security Assertion Markup Language (SAML) V2.0", OASIS Standard saml-authn-context-2.0-os.pdf, March 2005. [SAMLCore] OASIS, "Assertions and Protocol for the OASIS Security Assertion Markup Language (SAML) V2.0", OASIS Standard saml-core-2.0-os.pdf, March 2005. 10.2 Informative References [I-D.ietf-geopriv-common-policy] Schulzrinne, H., Morris, J., Tschofenig, H., Polk, J., and J. Rosenberg, "A Document Format for Expressing Privacy Preferences", draft-ietf-geopriv-common-policy-04 (work in progress), February 2005. Author's Address Christian Guenther Siemens Otto-Hahn-Ring 6 Munich, Bavaria 81739 Germany Email: christian.guenther@siemens.com Guenther Expires January 14, 2006 [Page 18] Internet-Draft SAML in Authorization Policies July 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Guenther Expires January 14, 2006 [Page 19]