Multi-Party Electronic Contract Signing Protocol Based on Blockchain

Abstract

With the development of Internet technology, the demand for signing electronic contracts has been greatly increased. The electronic contract generated by the participants in an online way enjoys the same legal effect as paper contract. The fairness is the key issue in jointly signing electronic contracts by the involved participants, so that all participants can either get the same copy of the contract or nothing. Most existing solutions only focus on the fairness of electronic contract generation between two participants, where the digital signature can effectively guarantee the fairness of the exchange of electronic contracts and becomes the conventional technology in designing the contract signing protocol. In this paper, an efficient blockchain-based multi-party electronic contract signing (MECS) protocol is presented, which not only offers the fairness of electronic contract generation for multiple participants, but also allows each participant to aggregate validate the signed copy of others. Security analysis shows that the proposed MECS protocol enjoys unforgeability, non-repudiation and fairness of electronic contracts, and performance analysis demonstrates the high efficiency of our construction.

Privacy‐preserving blockchain‐based contract signing with multi‐party supervision

“…The comparison demonstrates that our scheme takes much less time than Zhang et al's scheme, 3 and enjoys similar performance as Zhang et al's scheme. 6 In the KeyGen and AgVeri phases, the time taken by our scheme is about one-third of that by Zhang et al's scheme. 3 In the SigGen phase, our scheme takes about half the time of Zhang et al's scheme.…”

“…In addition, Zhang et al's scheme 3 also uses multiple scalar multiplication operations, while our scheme only uses a small amount of modular exponentiation operations, so the aggregate verification (AgVeri) cost in our scheme is lower than that of Zhang et al's scheme 3 and Wang et al's scheme 35 . Zhang et al's scheme 6 and our scheme have the same number of modular exponentiation operations, so the AgVeri costs of the two schemes are roughly the same. Although Wang et al's scheme 35 has more Adj and Ver algorithms than ours, our scheme has more functions such as COPEnc (COP Encryption), RCDec (RC Decryption), RkGen (Rekey Generation), Re‐enc (RC Re‐encryption), and SUPDec (SUP Decryption) than 3,6,35 .…”

“…Although Wang et al's scheme 35 has more Adj and Ver algorithms than ours, our scheme has more functions such as COPEnc (COP Encryption), RCDec (RC Decryption), RkGen (Rekey Generation), Re-enc (RC Re-encryption), and SUPDec (SUP Decryption) than. 3,6,35 Table 3 compares the functions of our scheme with those of other schemes. 3,6,35 All schemes guarantee the fairness of signature exchange, but Zhang et al's scheme 6 and our scheme can support multi-user environment and aggregate verification.…”

“…3,6,35 Table 3 compares the functions of our scheme with those of other schemes. 3,6,35 All schemes guarantee the fairness of signature exchange, but Zhang et al's scheme 6 and our scheme can support multi-user environment and aggregate verification. Wang et al's scheme 35 relies on a TTP, while none of the others does.…”

“…Blockchain can establish trust between completely distrusted nodes, so blockchain can function as a decentralized TTP. In view of the characteristics of blockchain, the introduction of blockchain to ensure the fairness of electronic contract signing protocols has received extensive attention 3‐6 . With blockchain technology, data loss or tampering of a single node will not affect the authenticity and integrity of data on the whole chain, thus ensuring the security and reliability of electronic contracts.…”