ITIS 60108010: Wireless Network Security

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ITIS 6010/8010 Wireless Network Security

• Weichao Wang

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• Secure Efficient Ad Hoc Distance Vector (SEAD)
• Is based on DSDV
• Use hash chain to accomplish authentication and
  avoid DoS
• Assumptions
• The diameter of the network is shorter than m
  hops
• Use hash chains to authenticate route updates
• The hash results are used in groups of m
• New hash chains can be generated when old ones
  are finished

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• Very similar to SAODV use hash chain to make
  sure a malicious node cannot decrement the
  distance vector
• Use sequence number to determine which group of
  hash values will be used for authentication
• Example
• Node S generates a hash chain with length 1000,
  and network diameter is m. for sequence i, k
  (1000 / m) i, the node will use hash value
  h(km) to h(kmm-1)

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• In this way, we prevent the fake sequence number
• A node will verify the hash value before updating
  its routing table. It hashes again to match the
  increased distance metric.
• Why we try to reduce digital signature
• Too much computation overhead
• Can be used to conduct DOS attack

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• Advantage over SAODV
• SAODV uses digital signature to protect the
  sequence number, but SEAD binds sequence number,
  hop metric, and hash chain together
• We do not need to sign the final hash result
  every time
• Performance comparison to DSDV
• Higher delivery ratio but longer delay
• Higher packet and byte overhead

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• Ariadne
• On-demand protocol based on DSR
• Based on TESLA to authenticate packets
• Need loosely synchronized clocks

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• Intro of TESLA
• Is a broadcast authentication protocol
• Depend on clock synchronization and delayed
  disclosure
• Every node generates a hash chain, and the
  previous hash value can be used to authenticate
  the later values
• The node discloses the hash result at a
  determined interval
• Use a not-published-yet hash value as key for
  symmetric encryption or MAC
• The receivers can authenticate the packet later
  when the key is disclosed

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• Example
• The clock synchronization error is ?, longest
  end-to-end delay is t, node S will chose a key
  that will not be disclosed until t2 ?
• The receiver will examine the key and make sure
  that it has not been disclosed. Otherwise, the
  packet can be generated by an attacker
• The receiver buffers the packet until the key is
  disclosed to authenticate the packet

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• Basic Ariadne Route Discovery
• Node S wants to locate a path to D, A to C in the
  middle
• Want to enforce three features
• S and D can authenticate each other
• Both S and D can authenticate the intermediate
  nodes (maybe only one of S and D)
• No intermediate node is missing

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• Both pairwise keys and TESLA keys are used
• S and D authenticate each other with pairwise key
• The intermediate nodes can be authenticated by
• TESLA keys with delayed disclosure, but S has to
  trust D to authenticate all intermediate nodes
• Every intermediate node signs the route request
• Pair wise key between D and the intermediate
  nodes
• Per-hop hashing to make sure no node is removed
• Example Ariadne using TESLA

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• Route Error with TESLA
• A node C finds that the link CD breaks, so it
  sends a route error back to S with TESLA key
  authentication. This path will be used until
  delayed authentication is confirmed. (hint TESLA
  uses delayed disclosure and authentication)
• Question if we already have pairwise keys, what
  is the advantage of using TESLA??

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• Summary
• WatchDog PathFinder DSR
• SAODV Digital signature Hash chain, AODV
• SEAD Hash chain, DSDV
• Ariadne Pairwise key hash chain delayed
  disclosure, DSR