Network Working Group Chunqiang. Li Internet-Draft Huawei Technologies Intended status: Standards Track November 12, 2007 Expires: May 9, 2008 Deriving Fast Handover Key from MSK to secure the FMIPv6 signaling draft-li-mipshop-fbu-sec-00.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 May 9, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Li Expires May 9, 2008 [Page 1] Internet-Draft FMIPv6 Security November 2007 Abstract This specification introduces an alternate, low-consumption mechanism for protecting signaling messages between the Mobile Node and previous Access Router for Fast Mobile IPv6. The alternate method defined here utilizes the Master Session Key(MSK) generated from EAP authentication to derive a fast handover key between the Mobile Node and the Access Router in order to avoid certain attacks. This mechanism also adds the Mobile Node Identifier option and the mobility message authentication option to the FMIPv6 signaling messages. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 5 4. Messages Flow . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . . . 11 Li Expires May 9, 2008 [Page 2] Internet-Draft FMIPv6 Security November 2007 1. Introduction In order to reduce the handover latency, Fast Mobile IPv6(FMIPv6) RFC4068 [2], proposes a fast handover mechanism for IPv6 Mobile Nodes. It requires a tunnel between the previous Access Router and the Mobile Node. The MN sends a "Fast Binding Update" message to its previous Access Router to establish this tunnel. Without corresponding verification of FBU, an attacker can redirect a victim node's traffic at will. To avoid certain attacks, the FMIPv6 signaling messages between the mobile node and the access router must be secured to ensure FMIPv6 support for a legitimate mobile node that has been authorized to obtain such services. The extensible authentication protocol (EAP)RFC3748 [3] is a generic framework supporting multiple types of authentication methods. According to the document RFC3748 [3],after successful authentication, the authentication server transports the Master Session Key(MSK) to the authenticator. The underlying L2 or L3 protocol can uses the MSK to derive additional keys. Generally, the MSK is used for bootstrapping the security associations for the access link between the mobile node and the network. Fast Mobile IPv6 requires that a Fast Binding Update is secured using a security association between an Access Router and a Mobile Node. In this document, a method for establishing a shared secret key between the Access Router and the Mobile Node is defined to protect this signaling. The mechanism utilizes the MSK to derive a fast handover key shared between the Mobile Node and previous Access Router. The access authentication is to authorize the Mobile Node to obtain the access link's network services; and FMIPv6 denotes that MN still continues to use the network services provided by the previous link, therefore, from the authorization view, applied the access authentication key to protect the FMIPv6 signaling is appropriate. Li Expires May 9, 2008 [Page 3] Internet-Draft FMIPv6 Security November 2007 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 [1]. Li Expires May 9, 2008 [Page 4] Internet-Draft FMIPv6 Security November 2007 3. Applicability Statement This mechanism is useful in scenarios where the following conditions are all met: -The authenticator is co-located with the access router, furthermore, the previous access router acted as the authenticator of the mobile node. -After successful authentication, the MSK was generated,so the EAP method used by mobile node should support the generation of MSK. Li Expires May 9, 2008 [Page 5] Internet-Draft FMIPv6 Security November 2007 4. Messages Flow The figure below describes the sequence of messages sent and received between the MN and pAR in the registration process. Fast Binding Update (FBU) and Fast Binding Acknowledgement (FBack) messages are used in the registration process. MN pAR/Authenticator | FBU to pAR | (a) |----------------------------------------------------->| | (including MN-ID option, | | mobility message authentication option) | | | | AR/Authenticator authenticates MN | | | FBack to MN | (b) |<-----------------------------------------------------| | (including MN-ID option, | | mobility message authentication option) | | | Figure 1: Fast Binding Update to AR The MN needs to signal the pervious AR by FBU message during the MIPv6 fast handover procedure, the MN utilizes the fast handover key dervied from MSK and corresponding authentication algorithm to generate the message authentication code of FBU. The Mobile Node MUST use the Mobile Node Identifier option, specifically the MN-NAI mobility option as defined in RFC4283 [4] to identify itself while authenticating with the previous AR. As specified by FMIPv6, the MN MUST include the old care-of address in a Home Address Option. Upon receiving FBU message containing authentication code and MN-NAI option, according to the MN-NAI, the pAR figured out the MSK, utilized the same method with mobile node to derive the fast handover key, and then applied this key to verify the authentication code included in the mobility message authentication option. The FMIPv6 document provides more detail on how the previous AR processes an FBU containing an authentication code. Li Expires May 9, 2008 [Page 6] Internet-Draft FMIPv6 Security November 2007 5. Security Considerations This document describes a shared key establishing method for FMIPv6 protocol. The key establishing method utilizes the MSK to derive a child key to protect the FMIPv6 signaling. This mechanism can defend against the other malicious node to impersonate a legal Mobile Node to send faked FBU messages. However, lack of verification the ownership of care-of addresses, a malicious node can send a FBU message to redirect traffic to an incorrect address or to steal another node's traffic with the genuine security association. Obviously, owing to the security association established from the successful authentication, according to the MN-NAI in the FBU messages, the AR can track the malicious node. From the administrative view, this can limit the attacks from the nodes with the genuine security association. For other FMIPv6 security considerations, please see the FMIPv6 document RFC4068 [2]. Li Expires May 9, 2008 [Page 7] Internet-Draft FMIPv6 Security November 2007 6. IANA Considerations There are no IANA considerations introduced by this draft. Li Expires May 9, 2008 [Page 8] Internet-Draft FMIPv6 Security November 2007 7. References [1] Bradner, S, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2131, March 1997. [2] R. Koodli, "Fast Handovers for Mobile IPv6", July 2005. [3] B. Aboba, "extensible authentication protocol", June 2004. [4] A. Patel, "Mobile Node Identifier Option for Mobile IPv6", November 2005. Li Expires May 9, 2008 [Page 9] Internet-Draft FMIPv6 Security November 2007 Author's Address Chunqiang Li Huawei Technologies Email: li.chunqiang@huawei.com Li Expires May 9, 2008 [Page 10] Internet-Draft FMIPv6 Security 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. 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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). Li Expires May 9, 2008 [Page 11]