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International Conference on Availability, Reliability and Security (ARES)

Achieving fairness and timeliness in a previous electronic contract signing protocol

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

Published Jan 1, 2006• 6 citations

Abstract

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.

DOI: 10.1109/ares.2006.22

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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.

Based on perfect concurrent signature, a novel fair exchange protocol was presented. In this protocol anyone can’t identify who has signed which signature when two parties have exchanged their two ambiguous signatures and rela- tive data items. Not until the initial signer publishes a secret information, are the two signatures bound to respective signer concurrently. After that, the other party sends the key of decrypting goods, and thus the two parties can fairly get each other’s data items without the trusted third party (TTP), which avoids the possibility of two parties’ collusion and the bottleneck of the TTP involvement. Through analysis, this protocol well ensures some significant properties of fair ex- change, such as fairness, non-repudiation and abuse-free etc. What’s more, it only needs four messages between two par- ties and it is very simple and highly efficient.

An exchange protocol is a protocol that allows two or more parties to exchange electronic information. Bao et al. proposed a multi-party fair exchange protocol based on an offline TTP. Participants in this protocol have to trust the initiator of the exchange in addition of the TTP. In this paper we present an improved optimistic multi-party fair exchange protocol in which participants do not have to trust anyone except for the TTP. Moreover, the communication overhead of our protocol is not increased.

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.

An Optimistic fair exchange (OFE) protocol is a good way for two parties to exchange their digital items in a fair way such that at the end of the protocol, both of them receive their items or none of them receives anything. In 2008, Huang et al. presented an efficient OFE protocol, but there is a security problem in their scheme. If the trusted third party (TTP) is dishonest and colludes with the verifier, the TTP can complete the transaction without getting signer's agreement. To solve this problem, we propose an OFE protocol in which there is a tracing algorithm to detect the party who completes the transaction. Furthermore, we obtain the accountability property introduced by Huang et al. in 2011, more efficiently and in the standard model while their protocol is in the random oracle model. We prove the security of our scheme under the chosen-key model and multi-user setting in the standard model.

Today in the field of security there are various protocols and authentication techniques that makes an application in the network more secure and free from various attacks in the network. There are various applications which require exchange of data between parties. A fair exchange is required since the chances of attacks have been greatly increased. Hence a new protocol has been implemented for the fair exchange of data between parties called contract signing protocol. Although there are various techniques applied for the security of these contract signing protocols such as using RSA [1]. This protocol use RSA to generate digital signature for the authentication of fair exchange between two parties, also in this technique instead of using single TTP (Trusted Third Party) and the trust can be distributed on multi TTP's. But the protocol implemented here in these techniques has less security issues and the chances of attack are more and also by using multiple TTP's storage cost is increased. Hence to overcome these limitations we propose an efficient and secure protocol of contract signing using OTPK (One Time Private Key). This technique requires less storage cost since there is no need to store any key at any end.