Cryptanalysis of the shpilrain-ushakov protocol for Thompson's group

Abstract

This paper shows that an eavesdropper can always recover efficiently the private key of one of the two parts of the public key cryptography protocol introduced by Shpilrain and Ushakov (ACNS 2005, Lecture Notes in Comput. Sci., vol. 3531, pp. 151-163, 2005). Thus an eavesdropper can always recover the shared secret key, making the protocol insecure. © 2007 International Association for Cryptologic Research.