An efficient undeniable signature scheme using braid groups

The signature schemes are used to verify the authenticity of a signature and the corresponding documents. The undeniable signature schemes are challenge and response based interactive schemes, where the active participation of signer is compulsory. These schemes are used in private communication where the confidential deals and agreements take place as a legitimate signer cannot deny his signature. In this paper, we analyze the Thomas and Lal´s braid group based zero-knowledge undeniable signature scheme and show that it is insecure against the man-in-the-middle and impersonation attacks. In addition, we propose an efficient undeniable signature scheme using the braid groups that provides secrecy and authenticity of a legitimate signer. Furthermore, we show that our scheme is secure against the above mentioned attacks.