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Jisuanji yingyong yanjiu

Analysis of Micali's Fair Contract Signing Protocol

Wang Zhi-ling, Yuqing Zhang

Published Jan 1, 2006• 0 citations
OpenAlex

Abstract

In PODC 2003,Micali presented a fair electronic exchange protocol for contract signing with an invisible trusted party.In this paper we re-analyze the protocol and find five new attacks.Moreover,we further demonstrated that the version given by Feng Bao et al.could be done better.In the end,we give a more efficient version of this protocol than that given by Feng Bao et al.

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In ACISP 04, the authors of (F. Bao et al., 2004) suggested a fair exchange protocol for electronic contract signing between two parts. The protocol is an improvement of a previous one (S. Micali, 2003) and solves the vulnerabilities of that protocol. In (F. Bao et al., 2004) one of the signers can contact a trusted third party to resolve the exchange if he can't conclude it in the usual way. However, the other signer cannot contact the trusted third party, and for this reason, this signer can't know the final state of the exchange until, if it is the case, the trusted third party contact him or her. In this paper we have improved the protocol so that both signers can contact the TTP and solve the exchange whenever they want. We propose an asynchronous and fair protocol that improves the protocol presented in (F. Bao et al., 2004) maintaining the efficiency of the original protocol.

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A fair protocol for signing contracts

Michael Ben-Or, Oded Goldreich, Silvio M. Micali +1 more

Two parties, A and B, want to sign a contract C over a communication network. To do so, they must simultaneously exchange their commitments to C. Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchanging partial commitments in piece-by-piece manner. During such a protocol, one party or another may have a slight advantage; a fair protocol keeps this advantage within acceptable limits. A new protocol is proposed. It is fair in the sense that, at any stage in its execution, the conditional probability that one party cannot commit both parties to the contract given that the other party can, is close to zero. This is true even if A and B have vastly different computing powers and is proved under very weak cryptographic assumptions.>

IEEE Transactions on Information Theory•Jan 1, 1990•287 citations
In PODC 2003,Micali presented a fair electronic exchange protocol for contract signing with an invisible trusted party.In this paper we re-analyze the protocol and find five new attacks.Moreover,we further demonstrated that the version given by Feng Bao et al.could be done better.In the end,we give a more efficient version of this protocol than that given by Feng Bao et al.
In ACISP 04, the authors of (F. Bao et al., 2004) suggested a fair exchange protocol for electronic contract signing between two parts. The protocol is an improvement of a previous one (S. Micali, 2003) and solves the vulnerabilities of that protocol. In (F. Bao et al., 2004) one of the signers can contact a trusted third party to resolve the exchange if he can't conclude it in the usual way. However, the other signer cannot contact the trusted third party, and for this reason, this signer can't know the final state of the exchange until, if it is the case, the trusted third party contact him or her. In this paper we have improved the protocol so that both signers can contact the TTP and solve the exchange whenever they want. We propose an asynchronous and fair protocol that improves the protocol presented in (F. Bao et al., 2004) maintaining the efficiency of the original protocol.
Electronic contract signing is an important issue in electronic commerce,while fair electronic contract signing protocol is an application model of fair exchange protocol,but there were defects in traditional fair electronic contract signing protocols.Presents a new fair electronic contract signing protocol based on the off-line trusted third party.The protocol effectively prevents all kinds of security attacks,and improves the efficiency of the implementation.The security of the newly devised scheme is also examined and proved.It is showed that fair processes of exchange activities are guaranteed in this protocol.
A fair contract-signing protocol allows two potentially mistrusted parities to exchange their commitments (i.e., digital signatures) to an agreed contract over the Internet in afairway, so that either each of them obtains the other's signature, or neither party does. Based on the RSA signature scheme, a new digital contract-signing protocol is proposed in this paper. Like the existing RSA-based solutions for the same problem, our protocol is not only fair, but also optimistic, since the trusted third party is involved only in the situations where one party is cheating or the communication channel is interrupted. Furthermore, the proposed protocol satisfies a new property-abuse-freeness. That is, if the protocol is executed unsuccessfully, none of the two parties can show the validity of intermediate results to others. Technical details are provided to analyze the security and performance of the proposed protocol. In summary, we present the first abuse-free fair contract-signing protocol based on the RSA signature, and show that it is both secure and efficient.
Based on Zhang's short signature scheme without random oracles and k+1-square roots assumption, a new fair contract signing protocol with the off-line semi-Trusted Third Party is given because the disadvantages of existed fair contract signing protocol. The off-line semi-TTP intervenes into the protocol in cases where one party attempts to cheat or simply crashes to make the fair exchange optimistic. The off-line TTP need not be completely trusted, since the TTP can get neither exchanged signature when dispute is mediated. Because this protocol is based on short signature, which needs low storage and little communication, it can be used in low-bandwidth communication and low-storage environments.
Two parties, A and B, want to sign a contract C over a communication network. To do so, they must simultaneously exchange their commitments to C. Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchanging partial commitments in piece-by-piece manner. During such a protocol, one party or another may have a slight advantage; a fair protocol keeps this advantage within acceptable limits. A new protocol is proposed. It is fair in the sense that, at any stage in its execution, the conditional probability that one party cannot commit both parties to the contract given that the other party can, is close to zero. This is true even if A and B have vastly different computing powers and is proved under very weak cryptographic assumptions.>