Potential Weaknesses of the Commutator Key Agreement Protocol Based on Braid Groups

  • Authors:
  • Sang-Jin Lee;Eonkyung Lee

  • Affiliations:
  • -;-

  • Venue:
  • EUROCRYPT '02 Proceedings of the International Conference on the Theory and Applications of Cryptographic Techniques: Advances in Cryptology
  • Year:
  • 2002

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Abstract

The braid group with its conjugacy problem is one of the recent hot issues in cryptography. At CT-RSA 2001, Anshel, Anshel, Fisher, and Goldfeld proposed a commutator key agreement protocol (KAP) based on the braid groups and their colored Burau representation. Its security is based on the multiple simultaneous conjugacy problem (MSCP) plus a newly adopted key extractor. This article shows how to reduce finding the shared key of this KAP to the list-MSCPs in a permutation group and in a matrix group over a finite field. We also develop a mathematical algorithm for the MSCP in braid groups. The former implies that the usage of colored Burau representation in the key extractor causes a new weakness, and the latter can be used as a tool to investigate the security level of their KAP.