Studies On Blind Group Signature And Fair Exchange Protocol

Blind group signature scheme is group signature scheme with the characteristic of blind signature, which is widely applied in electronic commerce and electronic government. This paper presents an efficient blind group signature scheme whose basic is Yuh-Min Tseng and Jinn-Ke Jan's improved group signature scheme based on discrete logarithm problem, and analyzes its security. XTR system is a new and efficient public key system introduced by Lenstra and Verheul in 2000, which is based on a new method to represent elements of a subgroup of multiplicative group of a finite field. This paper presents a blind group signature scheme based on XTR public key system, and analyzes its security and efficiency.A verifiable encryption scheme of digital signatures is in its basic form a two-party protocol between a prover and a verifier. In the protocol, the prover encrypts the valid signature on message, and then proves to the verifier that the encryption indeed contains the signature. Fair exchange means that two parties exchange digital signatures fairly over Internet. This paper builds a fair exchange protocol by means of G. Ateniese's verifiable encryption of digital signatures, and makes a concise analysis.