1. Handover Keys using AAA (draft-vidya-mipshop-fast-handover-aaa-01.txt)
Vidya Narayanan
Narayanan Venkitaraman
Hannes Tschofenig
Gerardo Giaretta
Julien Bournelle
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

2. draft-vidya-mipshop-fast-handover-aaa-01
Example Topology
AP2.1 MN
AP2.2
AR2
AAAH
Server
AP1.1
AR1 MN
AP1.2
Objective is to create a shared key between MN and AR using AAA
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

3. Protocol Overview AAA Server MN AR1 AR2 HKReq RADIUS Access Request
HMK Generated
HMK Generated
HKReq
([MN ID, Msg ID, Seq #, CoA],
MN-AAA Auth Option)
RADIUS Access Request
([[MN ID, Msg ID, Seq #, CoA], MN-AAA MAC, NAS IP], AR-AAA MAC)
Validate MAC
Generate HK1
RADIUS Access Accept
([Nonce, Lifetime] MN-AAA Auth Option, [HK1], ARn-AAA Key)
HKResp
Decrypt HK1
Generate HK1
([Nonce, Lifetime] MN-AAA Auth Option)
MN Handoff
To AR2
FNA([FBU], HK1)
[FBU], HK1
Validate FBU
FBAck
FBAck
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

4. Protocol Overview – Salient Points
Handover Master Key (HMK) shared between MN and AAAH
May be derived using EAP AMSK at time of power-up or first network access
HMK derived at the MN and AAA (EAP) Server
Not transported anywhere else
May be a pre-shared key between MN and AAAH
Handover Key (HK) Derivation
HK = HMAC-SHA1(HMK, AR ID | MN ID | AAA-MN Nonce, “Handover Key”)
HK derived with each AR
AR verifies MN CoA and binds it to the HK
HK may be derived indirectly with another AR through current AR
May be needed to derive a new key with a given AR after lifetime expires
E.g. pre-authentication before handoff
Lifetime value provided by AAA server; enforced by AR and MN
MN verifies HK with AR after handoff if pre-authentication was used
Used to bind HK to CoA of MN and to verify key is valid at AR
The protocol is similar to the MIP-AAA model
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

5. Additions/Changes since last version
Moved from UDP-based to Mobility Header type
HKReq and HKResp are now new MH types
Allows re-use of many already defined mobility options
Follows the model of FMIP control messages
Address Validation/Binding
Added details on CoA validation
Highlights of the procedure
AR performs NDP upon receiving HKReq with a non-NULL CoA
Message ID from HKReq added in the NS from AR as an option
MN that sent HKReq MUST NOT respond with NA
Address validated if no other response is received for the NS
Procedure similar to AR performing PND upon receiving HI or FNA
The AR *may* use other available means of address validation (as it may do so for the HI/FNA processing)
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

6. draft-vidya-mipshop-fast-handover-aaa-01
To-Dos
Derivation of Handover Master Key using EAP Key Hierarchy
Targeting separate I-D on the topic (use Appendix A in draft as basis)
Need EAP WG to solidify AMSK definition
RADIUS Attributes Definition
Targeting separate I-D on the topic (use Appendix B in draft as basis)
Diameter AVPs/Application Definition
Need to investigate possible re-use of NASREQ application
Targeting separate I-D on the topic (use Appendix C in draft as basis)
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

7. MN-AR Authentication Option (draft-narayanan-mn-ar-auth-option-00)
Defines a new Mobility Sub-option for carrying MN-AR Authentication Data
Based on the “Authentication Protocol for MIP6”
Protocol Gist:
Authentication Data = First (96, HMAC_SHA1(MN-AR Shared key, Mobility Data))
Mobility Data = care-of address | home address | MH Data
Used in draft-vidya-handover-keys-aaa-01 to include MN-AR Auth Data in HKReq/HKResp
Also suitable for carrying MN-AR Auth Data in FBU/FBAck in FMIPv6
Concerns on the dependency on information document
Raised on ML
Technically, the re-use makes sense
Integrate into 4068bis?
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01

8. draft-vidya-mipshop-fast-handover-aaa-01
Accept as WG item?
QUESTIONS?
November 7, 2005
draft-vidya-mipshop-fast-handover-aaa-01