Unlike ordinary digital signature systems, the verifier needs the help of the singer or the designated confirmer to verify undeniable signatures or confirmer signatures, respectively. In the past few years, several researches show the possible applications of undeniable signature in the e-commerce, e.g. [2][10][18]. However, there is an important problem in undeniable signature scheme. The signer must have the ability to decide who can corporate with him to verify the signature. In this paper, we propose a protocol that shows how to use smart card as an authentication tool in the undeniable signature scheme. The proposed protocol is based on a designated confirmer signature scheme proposed by M. Michels and M. Stadler[15]. Besides, in the above protocol, the cryptographic computation is based on elliptic curve cryptosystem for efficiency.
