PANA Working Group Y. Ohba Internet-Draft Toshiba Expires: May 15, 2008 November 12, 2007 Definition of Master Key between PANA Client and Enforcement Point draft-ohba-pana-pemk-00 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 May 15, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document defines PaC-EP Master Key (PEMK), a master key used between a PANA client and an enforcement point, for bootstrapping lower-layer ciphering. A PEMK is derived from EAP Master Session Key as a result of successful PANA authentication. The PEMK is defined to guarantee cryptographic independence among enforcement points across different types of lower-layers. Ohba Expires May 15, 2008 [Page 1]
Internet-Draft PaC-EP Master Key November 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Specification of Requirements . . . . . . . . . . . . . . . 3 2. PaC-EP Master Key . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Key Name of PEMK . . . . . . . . . . . . . . . . . . . . . 4 2.2. Scope of PEMK . . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Context of PEMK . . . . . . . . . . . . . . . . . . . . . . 4 2.4. Lifetime of PEMK . . . . . . . . . . . . . . . . . . . . . 5 3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 3.1. Channel Binding . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Guideline for distributing PEMK from PAA to EP . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Ohba Expires May 15, 2008 [Page 2]
Internet-Draft PaC-EP Master Key November 2007 1. Introduction PANA (Protocol for carrying Authentication for Network Access) [I-D.ietf-pana-pana] is designed to facilitate network access authentication and authorization of clients in access networks. It carries EAP [RFC3748] between a PaC (PANA Client) and a PAA (PANA Authentication Agent) where the PAA functions as an authentication gateway to the Authentication Server (AS). The PANA framework [I-D.ietf-pana-framework] defines an another entity referred to as an EP (Enforcement Point) which resides in the access network and allows access (data traffic) of authorized PaCs while preventing access by others depending on the PANA authentication and authorization result. The EP and PAA may be implemented on the same device or separate devices. The EP uses non-cryptographic or cryptographic filters to selectively allow and discard data packets. These filters may be applied at the link-layer or the IP-layer [I-D.ietf-pana-ipsec]. When cryptographic access control is used, a secure association protocol [RFC3748] needs to run between the PaC and EP. After completion of the secure association protocol, link or network layer per-packet security (for example TKIP, IPsec ESP) is enabled for integrity protection, data origin authentication, replay protection and optionally confidentiality protection. This document defines PaC-EP Master Key (PEMK) that is used by a secure association protocol as the pre-shared secret between the PaC and EP to enable cryptographic filters in the access network. The PEMK is defined to guarantee cryptographic independence among EPs across different lower-layer types. This document also describes guideline for distributing PEMKs from the PAA to EP. This document does not specify a mechanism for a PaC to know whether the lower-layer requires a secure association protocol or the pre- shared secret for the secure association protocol needs to be bootstrapped from PANA authentication. Such a mechanism may be defined by each lower-layer protocol. 1.1. Specification of Requirements In this document, several words are used to signify the requirements of the specification. These words are often capitalized. 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]. Ohba Expires May 15, 2008 [Page 3]
Internet-Draft PaC-EP Master Key November 2007 2. PaC-EP Master Key A PEMK (PaC-EP Master Key) is derived from the available MSK. The PEMK is 64 octets in length and it is calculated as follows: PEMK = prf+(MSK, "PaC-EP master key" | SID | KID | EPDID) o The prf+ function is defined in IKEv2 [RFC4306]. The pseudo- random function used for the prf+ function is specified in the PRF-Algorithm AVP carried in a PANA-Auth-Request message with 'S' (Start) bit set. o MSK is a Master Session Key generated by EAP and exported to PANA. o SID is a four-octet PANA session identifier [I-D.ietf-pana-pana]. o KID is the content of the PANA Key-ID AVP associated with the MSK [I-D.ietf-pana-pana]. o EP-Device-ID is the identifier of the EP. The first two octets of the Value field of this AVP represents the AddressType, which contains an Address Family defined in [IANAADFAM]. The AddressType is used to discriminate the content and format of the remaining octets for the address value. The use of address family and address value guarantees the cryptographic independence of PEMKs among multiple EPs across multiple lower-layer protocols. How a PaC configures the identifier of the EP is out of the scope of this document. 2.1. Key Name of PEMK The key name of the PEMK is defined as follows. TBD. 2.2. Scope of PEMK A PEMK is used between a PaC and an EP. A PEMK MUST NOT be shared among multiple PaCs or EPs. 2.3. Context of PEMK A PEMK is used as the pre-shared key of the secure association protocol in the scope of the PEMK. A PEMK MUST NOT be used for any other usage. Ohba Expires May 15, 2008 [Page 4]
Internet-Draft PaC-EP Master Key November 2007 2.4. Lifetime of PEMK The lifetime of a PEMK MUST be no greater than the lifetime of the MSK. 3. Security Considerations The following considerations are specifically made to follow the AAA key management guidance [RFC4962]. Other AAA key management requirements such as key lifetime, key scope, key context and key name are described under Section 2. 3.1. Channel Binding Since the device identifier of the EP is involved in the key derivation function, Channel Binding on a PEMK is made between the PaC and PAA at the time when the PEMK is generated. If a malicious EP advertises a different device identifier than that is registered with the PAA, the malicious attempt will not succeed since the secure association protocol will fail due to the difference between the PEMK calculated by the PaC and the PEMK calculated by the PAA and distributed to the EP. 3.2. Guideline for distributing PEMK from PAA to EP When an EP is implemented on the same device as the PAA, no protocol needs to be used for distributing a PEMK from the PAA to the EP. It is assumed that an EP is implemented on the same device as the PAA when the device identifier of the EP is equals to a link-layer address or an IP address of the PAA. Otherwise, it is assumed that the EP is implemented on a separate device from the PAA. In the case where the EP is implemented on a separate device from the PAA, a protocol is needed to distribute a PEMK from the PAA to the EP. Such a key distribution protocol may depend on the lower-layer protocol over which PANA operates. A key distribution protocol for a PEMK MUST ensure that the PEMK is encrypted as well as integrity and replay protected, with a security association between the PAA and EP, where the security association MUST be cryptographically bound to the identities of the PAA and EP known to the PaC. The HOKEY (Handover Keying) key distribution protocol [I-D.ietf-hokey-key-mgm] is such a key distribution protocol. 4. IANA Considerations This document has no actions for IANA. Ohba Expires May 15, 2008 [Page 5]
Internet-Draft PaC-EP Master Key November 2007 5. Acknowledgments TBD. 6. References 6.1. Normative References [I-D.ietf-pana-pana] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. Yegin, "Protocol for Carrying Authentication for Network Access (PANA)", draft-ietf-pana-pana-18 (work in progress), September 2007. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, June 2004. [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. [IANAADFAM] IANA, "Address Family Numbers", http://www.iana.org/assignments/address-family-numbers. 6.2. Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4962] Housley, R. and B. Aboba, "Guidance for Authentication, Authorization, and Accounting (AAA) Key Management", BCP 132, RFC 4962, July 2007. [I-D.ietf-pana-framework] Jayaraman, P., Ohba, Y., Parthasarathy, M., and A. Yegin, "Protocol for Carrying Authentication for Network Access (PANA) Framework", draft-ietf-pana-framework-10 (work in progress), September 2007. [I-D.ietf-pana-ipsec] Parthasarathy, M., "PANA Enabling IPsec based Access Control", draft-ietf-pana-ipsec-07 (work in progress), July 2005. [I-D.ietf-hokey-key-mgm] Nakhjiri, M. and Y. Ohba, "Derivation, delivery and Ohba Expires May 15, 2008 [Page 6]
Internet-Draft PaC-EP Master Key November 2007 management of EAP based keys for handover and re- authentication", draft-ietf-hokey-key-mgm-01 (work in progress), November 2007. Author's Address Yoshihiro Ohba Toshiba America Research, Inc. 1 Telcordia Drive Piscateway, NJ 08854 USA Phone: +1 732 699 5365 Email: yohba@tari.toshiba.com Ohba Expires May 15, 2008 [Page 7]
Internet-Draft PaC-EP Master Key November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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. 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, THE IETF TRUST 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. Intellectual Property 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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Ohba Expires May 15, 2008 [Page 8]
