Paper 2005/205

Another look at HMQV

Alfred Menezes


HMQV is a `hashed variant' of the MQV key agreement protocol. It was recently introduced by Krawczyk, who claimed that HMQV has very significant advantages over MQV: (i) a security proof under reasonable assumptions in the (extended) Canetti-Krawczyk model for key exchange; and (ii) superior performance in some situations. In this paper we demonstrate that HMQV is insecure by presenting realistic attacks in the Canetti-Krawczyk model that recover a victim's static private key. We propose HMQV-1, a patched version of HMQV that resists our attacks (but does not have any performance advantages over MQV). We also identify the fallacies in the security proof for HMQV, critique the security model, and raise some questions about the assurances that proofs in this model can provide.

Note: See the last page of the paper for a list of updates.

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2011-08-15: last of 8 revisions
2005-06-30: received
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      author = {Alfred Menezes},
      title = {Another look at HMQV},
      howpublished = {Cryptology ePrint Archive, Paper 2005/205},
      year = {2005},
      note = {\url{}},
      url = {}
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