Abstract.
In this paper we cryptanalyze two protocols: the Grigoriev–Shpilrain authentication protocol and a public key cryptosystem due to Wang, Wang, Cao, Okamoto and Shao. Both of these protocols use the computational hardness of some variations of the conjugacy search problem in a class of noncommutative monoids. We devise a practical heuristic algorithm solving those problems. As a conclusion we claim that these protocols are insecure for the proposed parameter values.
Funding source: NSF
Award Identifier / Grant number: DMS-0914773, DMS-1318716
The authors would like to thank the anonymous referees for their valuable comments and suggestions.
© 2014 by Walter de Gruyter Berlin/Boston
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