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.
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.
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.
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.
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.
Fair exchange of digital signatures is an important tool for signing digital contracts, e-payment and other electronic commerce actions. An ID-based scheme of fair exchange of digital signature is proposed in this paper. The protocol relies on a trusted third party, but is “optimistic”, in that the third party is only needed in cases where one player attempts to cheat or simply crashes. The proposed scheme has properties of short signature, low computation and verification cost. It can realize exchange of digital signatures fairly and efficiently. A key feature of our scheme is that it is identity-based, which needs no certificates and has a simple key management. To our best knowledge, this is the first identity-based scheme of fair exchange of digital signatures.
We present protocols for fair exchange of electronic data (digital signatures, payment and confidential data) between two parties A and B. Novel properties of the proposed protocols include: 1) offline trusted third party (TTP), i.e., TTP does not take part in the exchange unless one of the parties behaves improperly; 2) only three message exchanges are required in the normal situation; 3) true fair exchange, i.e., either A and B obtain each other's data or no party receives anything useful; no loss can be incurred to a party no matter how maliciously the other party behaves during the exchange. This last property is in contrast to previously proposed protocols with offline TTP ([1] and [21]), where a misbehaving party may get another party's data while refusing to send his document to the other party, and the TTP can provide affidavits attesting to what happened during the exchange. To our knowledge, the protocols presented here are the first exchange protocols which use offline TTP and at the same time guarantee true fair exchange of digital messages. We introduce a novel cryptographic primitive, called the Certificate of Encrypted Message Being a Signature (CEMBS), as the basic building block of the fair exchange protocols. It is used to prove that an encrypted message is a certain party's signature on a public file, without revealing the signature. We also give two examples to show in detail how the certificate can be constructed.