Some Remarks on a Fair Exchange Protocol

Fair exchange turns out to be an increasingly important topic due to the rapid growth of electronic commerce. An exchange is deemed to be fair if at the end of exchange, either each party receives the expected item or neither party receives any useful information about the other’s item. Several protocols for fair exchange have been proposed in recent years. In this paper, we first examine a newly published fair exchange protocol and point out its flaws and weaknesses. We then put forward a more efficient and secure protocol and give an informal analysis.

[1]  Ernest F. Brickell,et al.  Gradual and Verifiable Release of a Secret , 1987, CRYPTO.

[2]  Silvio Micali,et al.  A fair protocol for signing contracts , 1990, IEEE Trans. Inf. Theory.

[3]  Michael Wiener,et al.  Advances in Cryptology — CRYPTO’ 99 , 1999 .

[4]  Robert H. Deng,et al.  Efficient and practical fair exchange protocols with off-line TTP , 1998, Proceedings. 1998 IEEE Symposium on Security and Privacy (Cat. No.98CB36186).

[5]  Ivan Damgård.  Practical and Provably Secure Release of a Secret and Exchange of Signatures , 1993, EUROCRYPT.

[6]  Tor Helleseth,et al.  Advances in Cryptology — EUROCRYPT ’93 , 2001, Lecture Notes in Computer Science.

[7]  Dieter Gollmann,et al.  An efficient non-repudiation protocol , 1997, Proceedings 10th Computer Security Foundations Workshop.

[8]  Paul F. Syverson,et al.  Weakly secret bit commitment: applications to lotteries and fair exchange , 1998, Proceedings. 11th IEEE Computer Security Foundations Workshop (Cat. No.98TB100238).

[9]  Michael K. Reiter,et al.  Fair Exchange with a Semi-Trusted Third Party (extended abstract) , 1997, CCS.

[10]  Kazuo Ohta,et al.  How to simultaneously exchange secrets by general assumptions , 1994, CCS '94.

[11]  N. Asokan,et al.  Asynchronous protocols for optimistic fair exchange , 1998, Proceedings. 1998 IEEE Symposium on Security and Privacy (Cat. No.98CB36186).

[12]  Dieter Gollmann,et al.  A fair non-repudiation protocol , 1996, Proceedings 1996 IEEE Symposium on Security and Privacy.

[13]  Carl Pomerance,et al.  Advances in Cryptology — CRYPTO ’87 , 2000, Lecture Notes in Computer Science.

[14]  Benjamin Cox,et al.  NetBill Security and Transaction Protocol , 1995, USENIX Workshop on Electronic Commerce.

[15]  Taher ElGamal,et al.  A public key cyryptosystem and signature scheme based on discrete logarithms , 1985 .

[16]  N. Asokan,et al.  Optimistic protocols for fair exchange , 1997, CCS '97.

[17]  Richard Cleve,et al.  Controlled Gradual Disclosure Schemes for Random Bits and Their Applications , 1989, CRYPTO.