A Note on the Undeniable Signature Scheme
Shi Wu-jie · Journal of Southwest University · 2008
It has been proved that, in the process of the disavowal protocol of the Chaum-van Antwerpen undeniable signature scheme, the probability of the verifier can discover the disavowal attempt of the signer is 1, instead of the commonly believed 1-1/p, if the parameters of the challenges are chosen properly; furthermore, all possible outcomes of the verification protocol are also given if the message space is taken to be Zp* other than its subgroup G of order q.