Paper 2004/096

On the Ambiguity of Concurrent Signatures

Yi Mu, Fangguo Zhang, and Willy Susilo

Abstract

We point out that the notion of {\em ambiguity} introduced in the concurrent signatures proposed by Chen, Kudla, and Paterson in Eurocrypt 2004 is incorrect. Any third party who observed two signatures can differentiate who has/have produced the signatures by performing the verification algorithm. We note that the model proposed in the paper is sound, but the concrete scheme does not really provide what is required in the model.

Note: The paper by Chen, Kudla, and Paterson can be downloaded from the Springer website