Mobile IPv6 Location Privacy Solutions UPDATE draft-irtf-mobopts-location-privacy-solutions-04.txt Ying Qiu, Fan Zhao, Rajeev Koodli

Mobopts IETF 68 2 Outline Why Need Location Privacy? How to Protect the Location Privacy? –Pseudo Home Address –Dynamic SPI –Home Binding Update –RR signaling –Correspondent Binding Update What is different from original operation?

Mobopts IETF 68 3 Analysis of Location Privacy in MIP6 IP Address Location Privacy and Mobile IPv6: Problem Statement : –draft-ietf-mip6-location-privacy-ps-07.txt

Mobopts IETF 68 4 Pseudo Home Address pHoA Requirements: –Secure –Routable –Dynamic pHoA = Prefix_m || Enc(Kph_i, interface ID) Kph_i = HMAC_SHA1(Kph, IPsec sequence number) where, Kph is the symmetrical key between MN and HA, and Prefix_m is one of home network prefixes

Mobopts IETF 68 5 Using RR to compute pseudo- hoa privacy keygen token = First (64, Kcn(home address set to all zeros | nonce | 2)) Kpm = SHA1 (privacy keygen token | care-of keygen token) pseudo home address = string XOR HoA String = First (128, HMAC_SHA1 (Kpm, (care-of address | Home nonce index | Care-of nonce index)))

Mobopts IETF 68 6 Dynamic SPI SPI update After getting BU and BA, HA and MN change their SPIs respectively in order to protect the profiling attack. new SPI = (the current SPI + SPI_increment) SPI_increment = First(8, HMAC_SHA1(Kph, the current SPI)) If SPI_increment = 0, then set SPI_increment = 1

Mobopts IETF 68 7 Home Binding Update Home Binding Update with IPsec Transport Mode (i) BU message: IPv6 header source = CoA destination = HA Destination option header Home Address option (pHoA) ESP header in transport mode (with dynamic SPI) Mobility header Home Binding Update Alternative CoA option (CoA) SA in Home Agent: SA_in (IN, spi_a’, home_agent, ESP, TRANSPORT): source = home_address & destination = home_agent & proto = MH

Mobopts IETF 68 8 Home Binding Update Home Binding Update with IPsec Transport Mode (ii) BA message: IPv6 header source = HA destination = CoA Destination option header Home Address option (pHoA) ESP header in transport mode (with dynamic SPI) Mobility header Home Binding Acknowledgement SA in Home Agent: SA_out (OUT, spi_b’, home_address, ESP, TRANSPORT): source = home_agent & destination = home_address & proto = MH

Mobopts IETF 68 9 Home Binding Update Home Binding Update with IPsec Tunneling Mode BU message: IPv6 header source = CoA destination = HA ESP header in Tunnel mode (with dynamic SPI) source = HoA destination = HA Mobility header Home Binding Update Alternative CoA option (CoA) BA message: IPv6 header source = HA destination = CoA ESP header in transport mode (with dynamic SPI) source = HA destination = HoA Mobility header Home Binding Acknowledgement

Mobopts IETF RR signaling CoTI/CoT no change HoTI in MN-HA path: IPv6 header source = CoA destination = HA ESP header in tunneling mode IPv6 header source = pHoA destination = CN Mobility header HoTI HoTI in HA-CN path: IPv6 header source = pHoA destination = CN Mobility header HoTI

Mobopts IETF RR signaling HoT in CN-HA path: IPv6 header source = CN destination = pHoA Mobility header HoT HoT in HA-MN path: IPv6 header source = HA destination = CoA ESP header in tunneling mode IPv6 header source = CN destination = pHoA Mobility header HoT

Mobopts IETF Correspondent Binding Update BU message IPv6 header source = CoA destination = CN Destination option pHoA Mobility header Seq# home nonce index care-of nonce index Enc(Kbm, iHoA) First (96, HMAC_SHA1 (Kbm, (care-of address | correspondent | BU))) where –Kbm = SHA1 (home keygen token | care-of keygen token) ; no change –home keygen token = First (64, HMAC_SHA1(Kcn, (pHoA | nonce | 0))) –care-of keygen token = First (64, HMAC_SHA1(Kcn, (CoA | nonce | 1))); no change –The identity address iHoA could be the real HoA or the first pHoA when established the session.

13 What is different from original operation? CN side: Original RR | With additional option | 1) check the packet MUST contain | the same a unicast routable home address | | 2) the Sequence Number field in | the same the Binding Update is greater | than the Sequence Number | received in the previous valid | Binding Update. | | 3) a Nonce Indices mobility option | the same MUST be present | | 4) the correspondent node MUST | In the network i, we use the re-generate the home keygen | same pHoA_i in HoTI_i and BU_i token and the care-of keygen | messages, and CoTI and CoT as token from the information | usual, so the new method can contained in the packet. It | generate the valid Kbm and then then generates the binding | pass the step. management key Kbm and uses | it to verify the authenticator | field in the Binding Update | | 5) create/update the BU entry | first decrypt the new item Enc(Kbm, iHoA), according to HoA | get the iHoA, then create/update | the BU entry according to the iHoA. | BINDING CACHE: pHoA  HoA iHoA CoA Lifetime Seq

14 What is different from original operation? HA side: Operation is almost the same as the original, but the key for searching the binding cache is the pHoA instead of the real HoA. MN side: The additional operation is that MN needs to generate a pHoA at every new location and store/update the pHoA in the binding update list. BINDING UPDATE LIST: pHoA iHoA CN HoA CoA Lifetime Seq# BINDING CACHE: pHoA HoA CoA Lifetime Seq#

Mobopts IETF BU format IPv6 header (source = care-of address, destination = correspondent node) – Destination Option – pseudo home address Mobility header Binding Update = (sequence number, home nonce index, care-of nonce index) First (96, HMAC_SHA1 (Kbm, (care-of address | correspondent | Binding Update)))

Q & A Thank You