Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Computer Research and Development

A Protocol for Signing Contracts Based on Oblivious Transfer

QU Ya

Published Jan 1, 2003• 0 citations
OpenAlex

Abstract

If two parties want to sign a contract C over a communication network, they must “simultaneously” exchange their commitments to C Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchange partial commitments in a piece by piece manner The party of secondly sending commitments may have a slight advantage; a “fair” protocol must keep this advantage within acceptable limits The protocol for signing a contract is improved based on the research result of secure multiparty computation In this protocol, the parties obliviously transfer the signed bit and the committed bit; the other parties can prove the validity of this bit based on the confirming sub protocol, but he can't gain more information about the whole signature by accumulating the signed bit or the committed bit After the parties exchange the whole signed information, they declare the commitment about the signature respectively, and gain the whole signature of the other party At this moment, the party doesn't care about the advance quit of the other party, because he has gained the whole signed information Finally, it is proved that this protocol is quit fairness

Related papers

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

An Abuse-Free Fair Contract-Signing Protocol Based on the RSA Signature

Guilin Wang

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.

IEEE Transactions on Information Forensics and Security•Nov 13, 2009•49 citations

Achieving fairness and timeliness in a previous electronic contract signing protocol

M. Magdalena Payeras–Capellà, Josep Lluís Ferrer Gomila, L. Huguet

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.

International Conference on Availability, Reliability and Security (ARES)•Jan 1, 2006•6 citations

Fair Contract Signing Protocol Based on Short Signature

Luo Wen-jun, Tong Ling, Zufeng Fu +1 more

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.

•Jul 1, 2010•1 citation

Efficient abuse‐free fair contract‐signing protocol based on an ordinary crisp commitment scheme

Alawi A. Al‐Saggaf, Lahouari Ghouti

A mathematical framework for conventional commitment schemes is proposed. Digital contract‐signing protocols represent an important application of the proposed framework, where usually two mistrusted parties wish to exchange their commitments in a fair way. Building on a variant of the proposed framework, an efficient contract‐signing protocol over the Internet is developed. The latter protocol is ‘optimistic, fairness and abuse‐free’. Detailed security and performance analyses are provided. The performance analysis reveals an important computational aspect of the proposed protocol which requires only ‘four rounds’ to complete unlike existing protocols. Moreover, the communication and computational costs are relatively small. Given these theoretical and practical features, the proposed contract‐signing protocol is not only of theoretical interest, but it also enjoys practical merits which make it very suitable for electronic transactions requiring online signature exchange.

IET Information Security•Jul 25, 2014•9 citations

A secure and fair DSA-based signature exchange protocol

Aleksandra Nenadić, Ning Zhang, S. Barton

This work presents a novel protocol for fair exchange of DSA-based signatures to support an e-commerce activity of digital contract signing. The protocol employs an off-line semitrusted third party (STTP), which participates in the protocol execution only in exceptional circumstances and which involvement in the protocol is transparent. The protocol can tolerate the STTP's own misbehaviour (i.e. if it does not collude with other participants of the protocol) and it prevents the STTP from gaining the exchanged signatures or the signed document. The protocol is based on the principle of verifiable and recoverable signature encryption, and in comparison with related protocols is more efficient.

IEEE Symposium on Computers and Communications (ISCC)•Jan 1, 2004•8 citations
If two parties want to sign a contract C over a communication network, they must “simultaneously” exchange their commitments to C Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchange partial commitments in a piece by piece manner The party of secondly sending commitments may have a slight advantage; a “fair” protocol must keep this advantage within acceptable limits The protocol for signing a contract is improved based on the research result of secure multiparty computation In this protocol, the parties obliviously transfer the signed bit and the committed bit; the other parties can prove the validity of this bit based on the confirming sub protocol, but he can't gain more information about the whole signature by accumulating the signed bit or the committed bit After the parties exchange the whole signed information, they declare the commitment about the signature respectively, and gain the whole signature of the other party At this moment, the party doesn't care about the advance quit of the other party, because he has gained the whole signed information Finally, it is proved that this protocol is quit fairness
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.>
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.
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.
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.
A mathematical framework for conventional commitment schemes is proposed. Digital contract‐signing protocols represent an important application of the proposed framework, where usually two mistrusted parties wish to exchange their commitments in a fair way. Building on a variant of the proposed framework, an efficient contract‐signing protocol over the Internet is developed. The latter protocol is ‘optimistic, fairness and abuse‐free’. Detailed security and performance analyses are provided. The performance analysis reveals an important computational aspect of the proposed protocol which requires only ‘four rounds’ to complete unlike existing protocols. Moreover, the communication and computational costs are relatively small. Given these theoretical and practical features, the proposed contract‐signing protocol is not only of theoretical interest, but it also enjoys practical merits which make it very suitable for electronic transactions requiring online signature exchange.
This work presents a novel protocol for fair exchange of DSA-based signatures to support an e-commerce activity of digital contract signing. The protocol employs an off-line semitrusted third party (STTP), which participates in the protocol execution only in exceptional circumstances and which involvement in the protocol is transparent. The protocol can tolerate the STTP's own misbehaviour (i.e. if it does not collude with other participants of the protocol) and it prevents the STTP from gaining the exchanged signatures or the signed document. The protocol is based on the principle of verifiable and recoverable signature encryption, and in comparison with related protocols is more efficient.