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
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Copyright (C) The IETF Trust (2007).
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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
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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.
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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].
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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.
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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.
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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].
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6. IANA Considerations
There are no IANA considerations introduced by this draft.
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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.
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Author's Address
Chunqiang Li
Huawei Technologies
Email: li.chunqiang@huawei.com
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