A Practical Attack on a Braid Group Based Cryptographic Protocol

  • Alexei Myasnikov
  • Vladimir Shpilrain
  • Alexander Ushakov
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3621)

Abstract

In this paper we present a practical heuristic attack on the Ko, Lee et al. key exchange protocol introduced at Crypto 2000 [11]. Using this attack, we were able to break the protocol in about 150 minutes with over 95% success rate for typical parameters. One of the ideas behind our attack is using Dehornoy’s handle reduction method as a counter measure to diffusion provided by the Garside normal form, and as a tool for simplifying braid words. Another idea employed in our attack is solving the decomposition problem in a braid group rather than the conjugacy search problem.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Alexei Myasnikov
    • 1
  • Vladimir Shpilrain
    • 2
  • Alexander Ushakov
    • 3
  1. 1.Department of MathematicsMcGill UniversityMontreal
  2. 2.Department of MathematicsThe City College of New YorkNew YorkUSA
  3. 3.Department of MathematicsCUNY Graduate CenterNew YorkUSA

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