1. Authentication and Key Management of MP with multiple radios
Month Year
doc.: IEEE yy/xxxxr0
March 2008
Authentication and Key Management of MP with multiple radios
Date:
Authors:
Charles Fan,Amy Zhang, Huawei
John Doe, Some Company

2. Month Year
doc.: IEEE yy/xxxxr0
March 2008
Abstract
This presentation states the CID #504 from LB126, the secure association setup problem when the multiple radios MP joins into the mesh network, and the suggested solution including the summary text change of the draft.
CID#504: PMK-MKD which is derived after the higher-layer authentication should only be related with the authentication credential and some other device information , not tighten-related with the MAC address of a radio. It would induce multiple authentication problems when the mesh node has two or more radios
解决什么问题 多radio的重复认证问题
Charles Fan,Amy Zhang, Huawei
John Doe, Some Company

3. Agenda Problem Statement Resolution March 2008
Charles Fan,Amy Zhang, Huawei

4. Current Secure association setup mechanism
March 2008
Current Secure association setup mechanism
Supplicant
Step2:
After MP authenticates with AS through MKD
PMK-MKD and MKDK will be derived using the current hierarchy
Mesh Authenticator
Step1: Authentication Method & Role & Key Management type Negotiation
Probe/Beacon
Peer Link Management
Step2:Authentication through MKD & The key hierarchy setup
Initial Authentication if needed
Step3: PTK/GTK distribution
4-Way handshake to build session keys
Secure communication
Charles Fan,Amy Zhang, Huawei

5. Current 802.11s Key Hierarchy
Month Year
doc.: IEEE yy/xxxxr0
March 2008
Current s Key Hierarchy
The PMK-MKD and MKDK are bound with SPA.
MeshTopLevelKeyData = KDF-768(XXKey, “Mesh Key Derivation”,MeshID, MKD-NAS-ID, MKDD-ID, SPA)
There will be multiple SPAs for a multi-radio Supplicant MP; hence there will be multiple PMK-MKDs and MKDKs
Multiple initial authentication procedures should have to be launched.
Held by MKD, Supplicant & MA
PMK-MA=KDF-256(PMK-MKD,”MA Key Derivation”, PMK-MKDName|| MA-ID|| SPA)
MSK/PSK
Held by MKD & Supplicant
PMK-MKD = L(MeshTopLevelKeyData, 0, 256)
Held & Derived by Supplicant & MA
PTK=KDF(PMK-MA,”Mesh PTK key derivation”,MPTKSNonce|| MPTKANonce|| MA-ID||SPA||PMK-MAName)
Held by Supplicant & MKD
MKDK = L(MeshTopLevelKeyData, 384, 256)
Held & Derived by Supplicant & MKD, deliver PMK-MA
MPTK-KD=KDF-256(MKDK, “Mesh PTK-KD Key”,MA-Nonce||MKD-Nonce||MA-ID||MKD-ID)
PMK-MA
PMK-MKD
PTK
MKDK
MPTK-KD
Key Distribution branch
Link Security Branch
Suggestions: MPTK-KD = KDF-256(MKDK, “Mesh PTK-KD Key”, MeshID, MKD-NASID, MKD-ID, Dev_ID, MA-Nonce, MKD-Nonce)
Charles Fan,Amy Zhang, Huawei
John Doe, Some Company

6. Disadvantages of multiple authentications
March 2008
Disadvantages of multiple authentications
Can not detect the authentication credential is used for different MPs or different radios in the same MP simultaneously.
The authentication credential may be used by multiple MPs simultaneously.
Increase the air cost overhead when launching multiple times initial authentication
Charles Fan,Amy Zhang, Huawei

7. Agenda Problem Statement Resolution March 2008
Charles Fan,Amy Zhang, Huawei

8. Solution Requirements
March 2008
Solution Requirements
The initial authentication should only be launched once when an MP join the mesh network, no matter how many radios it has.
Authentication credential is issued one MP device
One PMK-MKD and one MKDK for an MP, shared by all the radios
Different radio in the same MP should use different PTK.
Distribute keys for radios of the device through one time initial authentication procedure
There should be one MPTK-KD between an MA and MKD.
The communication between MKD and MP is not tied to a peer link with MAC addresses
Less modification, more better.
Charles Fan,Amy Zhang, Huawei

9. Possible solution March 2008
Introduce SP-ID which can only identify the supplicant MP to do the initial authentication.
SP-ID: the MAC address of the Supplicant MP. It is the one of the MAC address of the Supplicant MP if it has more than one PHY.
PMK-MKD and MKDK should bind with SP-ID, which can identify an MP.
Using the SP-ID instead of SPA when deriving PMK-MKD and MKDK
MeshTopLevelKeyData = KDF-768(XXKey, “Mesh Key Derivation”,MeshID, MKD-NAS-ID, MKDD-ID, SP-ID)
Only one MPTK-KD between an MA and MKD
The definition of MA-ID and MKD-ID are confused to a multi-radio MP because of multiple MAC addresses it has; extend the definitions
MA-ID: the MAC address of the MA; it is the one of the MAC address of the MA if it has more than one PHY.
MKD-ID: the MAC address of the MKD; it is the one of the MAC address of the MKD if it has more than one PHY.
Different PTKs are derived for different radios
Change the name of ‘MA-ID’ into ‘MAA’ (Mesh Authenticator Address) because the PTK should bind with peer link MAC addresses and the definition of MA-ID is no more just a MAC address.
MAA has the same definition of ‘MA-ID’ in s D2.0
Charles Fan,Amy Zhang, Huawei

10. 802.11s Key Hierarchy Clarify
Month Year
doc.: IEEE yy/xxxxr0
March 2008
802.11s Key Hierarchy Clarify
MAA: the authenticator MP’s MAC address
SPA: the supplicant MP’s MAC address
SP-ID: the MAC address of the Supplicant MP; it is the one of the MAC address of the Supplicant MP if it has more than one PHY.
MA-ID: the MAC address of the MA; it is one of the MAC addresses of the MA if it has more than one PHY.
MKD-ID: the MAC address of the MKD; it is the one of the MAC address of the MKD if it has more than one PHY
MeshTopLevelKeyData = KDF-768(XXKey, “Mesh Key Derivation”,MeshID, MKD-NAS-ID, MKDD-ID, SP-ID)
Bind with Radios
Held by MKD, Supplicant & MA
PMK-MA=KDF-256(PMK-MKD,”MA Key Derivation”, PMK-MKDName|| MAA|| SPA)
MSK/PSK
Bind with MPs
Held by MKD & Supplicant
PMK-MKD = L(MeshTopLevelKeyData, 0, 256)
Held & Derived by Supplicant & MA
PTK=KDF(PMK-MA,”Mesh PTK key derivation”,MPTKSNonce|| MPTKANonce|| MAA||SPA||PMK-MAName)
Held by Supplicant & MKD
MKDK = L(MeshTopLevelKeyData, 384, 256)
Held & Derived by Supplicant & MKD, deliver PMK-MA
MPTK-KD=KDF-256(MKDK, “Mesh PTK-KD Key”,MA-Nonce||MKD-Nonce||MA-ID||MKD-ID)
PMK-MA
PMK-MKD
PTK
MKDK
MPTK-KD
Key Distribution branch
Link Security Branch
Suggestions: MPTK-KD = KDF-256(MKDK, “Mesh PTK-KD Key”, MeshID, MKD-NASID, MKD-ID, Dev_ID, MA-Nonce, MKD-Nonce)
Charles Fan,Amy Zhang, Huawei
John Doe, Some Company

11. SP-ID included in initial authentication
March 2008
SP-ID included in initial authentication
Supplicant MP uses Peer Link Open tell the SP-ID to MA
MA transfers the SP-ID to MKD
Supplicant MP and MKD use SP-ID to derive the PMK-MKD and MKDK AS
Sup MP MA
MKD
2. EAPOL (EAP-Request Identity)
3. EAPOL (EAP-Response Identity)
5. EAP Transport (EAP-Response Identity)
7. EAP Transport (EAP-Success, MSK)
9. EAPOL (EAP-Success)
1. EAPOL-Start
4. Mesh EAP encapsulation (SP-ID)
Derive Pairwise Key (PMK-MKD, MKDK, PMK-MA)
8. Mesh EAP encapsulation(EAP-Response Accept PMK-MA)
6. EAP-specific (mutual) authentication
Peer Link Open (Request Authentication, SP-ID)
Charles Fan,Amy Zhang, Huawei

12. Updated text of the Draft
March 2008
Updated text of the Draft
New Abbreviations:
SP-ID: Mesh Supplicant Identifier
MAA: Mesh Authenticator Address
Change the SPA into SP-ID when deriving the MKDK and PMK-MKD.
Change the MA-ID into MAA when deriving the PMK-MA and PTK.
Add the SP-ID subfield in MSA IE in order to send the SP-ID to authenticator MP.
Change the SPA into SP-ID in EAP Authentication field to send the SP-ID to MKD.
Extend the definition of MA-ID and MKD-ID to support multiple radios MP.
Element ID
Length
Handshake Control
MA-ID
SP-ID
Selected AKM Suite
Selected Pairwise Cipher Suite
Chosen PMK
Local Nonce
Peer Nonce
Optional Parameters
Encapsulation Type
Replay Counter
SPA SP-ID
EAP Message Length
EAP Message
Charles Fan,Amy Zhang, Huawei

13. Summarization Less modification, more efficiency
March 2008
Summarization
Less modification, more efficiency
Add the term ‘SP-ID’ to identify the supplicant MP, because the SPA can not identify the MP, especially for the multiple radio MPs.
Add the SP-ID(6 bytes) field in MSA IE to transmit it to MA and then to MKD to do the key hierarchy
Extend the definition of MA-ID and MKD-ID to be an unique identify of the MP devices, which are more reasonable to be named as an identifier
Rename the ‘MA-ID’ to ‘MAA’ in PMK-MA and PTK derivation formula to make the PMK-MA and PTK bind with peer links
Charles Fan,Amy Zhang, Huawei

14. Reference Draft_P802.11s_D2.00 March 2008
Charles Fan,Amy Zhang, Huawei

15. March 2008
Straw Poll
Would you like to accept the changes presented in this slide and the detailed text update in 11-08/526r0 to s standard amendment.
Yes No
Abstain
Charles Fan,Amy Zhang, Huawei