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Authentication and Key Management of MP with multiple radios

Authentication and Key Management of MP with multiple radios. Date: 2008-05-12. Authors:. Abstract.

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Authentication and Key Management of MP with multiple radios

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  1. Authentication and Key Management of MP with multiple radios Date: 2008-05-12 Authors: Charles Fan,Amy Zhang, Huawei

  2. 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 Charles Fan,Amy Zhang, Huawei

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

  4. Current Secure association setup mechanism Supplicant Mesh Authenticator Step2: • After MP authenticates with AS through MKD • PMK-MKD and MKDK will be derived using the current hierarchy 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-Wayhandshaketobuildsessionkeys Securecommunication Charles Fan,Amy Zhang, Huawei

  5. Link Security Branch Key Distribution branch MSK/PSK Held by MKD & Supplicant PMK-MKD = L(MeshTopLevelKeyData, 0, 256) Held by Supplicant & MKD MKDK = L(MeshTopLevelKeyData, 384, 256) PMK-MKD MKDK Held byMKD, Supplicant & MA PMK-MA=KDF-256(PMK-MKD,”MA Key Derivation”, PMK-MKDName|| MA-ID|| SPA) PMK-MA 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) MPTK-KD Held & Derived bySupplicant & MA PTK=KDF(PMK-MA,”Mesh PTK key derivation”,MPTKSNonce|| MPTKANonce|| MA-ID||SPA||PMK-MAName) PTK Current 802.11s 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. Charles Fan,Amy Zhang, Huawei

  6. 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 Charles Fan,Amy Zhang, Huawei

  8. 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 • 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 Primary 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 primary MAC address of the MA if it has more than one PHY. • MKD-ID: the MAC address of the MKD; it is the Primary 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 802.11s D2.0 Charles Fan,Amy Zhang, Huawei

  10. Link Security Branch Key Distribution branch MSK/PSK Bind with Devices Held by MKD & Supplicant PMK-MKD = L(MeshTopLevelKeyData, 0, 256) Bind with Devices Held by Supplicant & MKD MKDK = L(MeshTopLevelKeyData, 384, 256) PMK-MKD MKDK Bind with Radios Held byMKD, Supplicant & MA PMK-MA=KDF-256(PMK-MKD,”MA Key Derivation”, PMK-MKDName|| MAA|| SPA) PMK-MA Bind with Devices 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) MPTK-KD Bind with Radios Held & Derived bySupplicant & MA PTK=KDF(PMK-MA,”Mesh PTK key derivation”,MPTKSNonce|| MPTKANonce|| MAA||SPA||PMK-MAName) PTK 802.11s Key Hierarchy Clarify • MAA: the authenticator MP’s MAC address • SPA: the supplicant MP’s MAC address • MA-ID: the MAC address of the MA; it is the primary MAC address of the MA if it has more than one PHY • MKD-ID: the MAC address of the MKD; it is the Primary 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) Charles Fan,Amy Zhang, Huawei

  11. MA MKD AS Sup MP Peer Link Open (RequestAuthentication, SP-ID) 1. EAPOL-Start 2. EAPOL (EAP-Request Identity) 4. Mesh EAP encapsulation (SP-ID) 3. EAPOL (EAP-Response Identity) 5. EAP Transport (EAP-Response Identity) 6. EAP-specific (mutual) authentication Derive Pairwise Key (PMK-MKD, MKDK, PMK-MA) 7. EAP Transport (EAP-Success, MSK) Derive Pairwise Key (PMK-MKD, MKDK, PMK-MA) 8. Mesh EAP encapsulation(EAP-Response AcceptPMK-MA) 9. EAPOL (EAP-Success) 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 Charles Fan,Amy Zhang, Huawei

  12. 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. Charles Fan,Amy Zhang, Huawei

  13. 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 Charles Fan,Amy Zhang, Huawei

  15. Straw Poll • Would you like to accept the changes presented in this slide and the detailed text update in 11-08/526r0 to 802.11s standard amendment. • Yes • No • Abstain Charles Fan,Amy Zhang, Huawei

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