Constructing fair-exchange protocols for E-commerce via distributed computation of RSA signatures

Abstract

Applications such as e-commerce payment protocols, electronic contract signing, and certified e-mail delivery require that fair exchange be assured. A fair-exchange protocol allows two parties to exchange items in a fair way so that either each party gets the other's item, or neither party does. We describe a novel method of constructing very efficient fair-exchange protocols by distributing the computation of RSA signatures. Specifically, we employ multisignatures based on the RSA-signature scheme. To date, the vast majority of fair-exchange protocols require the use of zero-knowledge proofs, which is the most computationally intensive part of the exchange protocol. Using the intrinsic features of our multisignature model, we construct protocols that require no zero-knowledge proofs in the exchange protocol. Use of zero-knowledge proofs is needed only in the protocol setup phase--this is a one-time cost. Furthermore, our scheme uses multisignatures that are compatible with the underlying standard (single-signer) signature scheme, which makes it possible to readily integrate the fair-exchange feature with existing e-commerce systems. Categories and Subject General TermsAlgorithms, Security, Design KeywordsFair-exchange protocols~ e-commerce, multisignatures, RSA signatures, zero-knowledge proofs.Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.

False Proof Reputation Management for P2P Networks

“…that d=d1+d2 mod Φ (n), by following park et aldid in [18].The signature of this user has to be exchanged with the other and this signature is…”

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

“…Actually, fair exchange includes the following different but related issues: contract signing protocols [20,12,16,6,2,4,23,33,7], certified e-mail systems [39,30,5,28,1], non-repudiation protocols [38,31,27], and epayment schemes in electronic commerce [15,34]. For more references and discussions on the relationships between those conceptions, please refer to [3,31].…”

“…Compared with the schemes belonging to previous two types, contract signing protocols with off-line TTP [2,3,4,6,34] are more appealing and practical for most applications. Because those protocols are optimistic in the sense that the TTP is not invoked in the execution of exchange unless one of the two parties misbehaves or the communication channel is out of order.…”

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“…In particular, the CS scheme proposed by Boyd and Foo is to split multiplicatively the secret key of a standard RSA signature. Recently, Park et al [22] propose a CS scheme which splits the key additively, and based on that, present a very efficient protocol in which the partial signature is non-interactively verifiable. But unfortunately, Dodis and Reyzin [10] break the scheme by proving the TTP can obtain Alice's entire secret key with only her registration information.…”