Geopriv C. Guenther Internet-Draft Siemens Expires: August 17, 2005 February 13, 2005 SAML in Authorization Policies draft-guenther-saml-policy-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 August 17, 2005. 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 August 17, 2005 [Page 1] Internet-Draft SAML in Authorization Policies February 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Basic Scenario . . . . . . . . . . . . . . . . . . . . . . . 5 4. SAML Conditions Example . . . . . . . . . . . . . . . . . . 6 5. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . 10 8. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 11 9. Normative References . . . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . 13 Guenther Expires August 17, 2005 [Page 2] Internet-Draft SAML in Authorization Policies February 2005 1. Introduction The Security Assertion Markup Language, see [SAML], 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 M. 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 August 17, 2005 [Page 3] Internet-Draft SAML in Authorization Policies February 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 August 17, 2005 [Page 4] Internet-Draft SAML in Authorization Policies February 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 August 17, 2005 [Page 5] Internet-Draft SAML in Authorization Policies February 2005 4. SAML Conditions Example This document extends the Common Policy markup language by adding new elements to the substitution group defined in the schema of the Common Policy markup language, see [I-D.ietf-geopriv-common-policy]. This paragraph provides a basic example of an XML document valid with respect to the XML schema defined in Section 5. https://www.idp.com/ urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport 2005-03-06T17:00:00-05:00 2005-03-11T19:00:00-05:00 Guenther Expires August 17, 2005 [Page 6] Internet-Draft SAML in Authorization Policies February 2005 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 condition which is defined by this document in Section 5. As there is no subelement of , this rule matches for each Subject identified in a SAML authentication assertion issued by idp.com that asserts that the Subject has been authenticated through the presentation of a password over a protected session (e.g., protected by SSL or IPSec). Guenther Expires August 17, 2005 [Page 7] Internet-Draft SAML in Authorization Policies February 2005 5. XML Schema Guenther Expires August 17, 2005 [Page 8] Internet-Draft SAML in Authorization Policies February 2005 6. Security Considerations [tbd] Guenther Expires August 17, 2005 [Page 9] Internet-Draft SAML in Authorization Policies February 2005 7. IANA Considerations [tbd] Guenther Expires August 17, 2005 [Page 10] Internet-Draft SAML in Authorization Policies February 2005 8. Open Issues 1) There are not only authentication assertions in SAML, but also authorization decision and attribute assertions. Inspect the usability of these types of SAML assertions in the scope of this document. 2) Modify and enhance the XML schema in accordance to 1). Possibly, it could be more appropriate to directly adopt XML element and type definitions as given in the SAML assertion schema instead of defining new ones. 3) It could be useful to let the element represent an XML schema that specizializes the SAML assertion schema with respect to the target of the authorization policy. Example: Instaed of listing all permitted authentication context class references in , you could write down a target-specific SAML assertion schema with an element whose definition is completely identical to the SAML definition of , except for the fact that only certain URIs are permitted as values to make the SAML assertion valid with respect to this specialized assertion schema. 4) Security considerations. 5) IANA considerations. 9. Normative 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", Internet-Draft draft-ietf-common-policy-03, October 2004. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [SAML] OASIS, "Assertions and Protocol for the OASIS Security Assertion Markup Language (SAML) V2.0", OASIS Committee Draft sstc-saml-core-2.0-cd-04.pdf, January 2005. Guenther Expires August 17, 2005 [Page 11] Internet-Draft SAML in Authorization Policies February 2005 Author's Address Christian Guenther Siemens Otto-Hahn-Ring 6 Munich, Bayern 81739 Germany Email: christian.guenther@siemens.com Guenther Expires August 17, 2005 [Page 12] Internet-Draft SAML in Authorization Policies February 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. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. 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 August 17, 2005 [Page 13]