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

Abstract

AbstractWith the advancement of information technology, electronic contracts are gradually replacing paper contracts. Blockchain can serve as a decentralized trusted third party to help signatories solve the fairness of electronic contract signing. However, most of the existing blockchain‐based contract signing protocols are only applicable to two‐party signing, and lack the supervision of the contract and the protection of its confidentiality under supervision. This article proposes a privacy‐preserving blockchain‐based contract signing system with multi‐party supervision (CSS), in which multiple supervisors are set up to supervise contracts by voting. Before supervision, an identity‐based multi‐receiver re‐encryption algorithm is used to encrypt the contract, which takes less computation and can control the access rights of different supervisors, thus ensuring the privacy of the contract. Security analysis shows that the proposed CSS system enjoys unforgeability, non‐repudiation and fairness of electronic contract signing, and realizes privacy protection and access control under multi‐party supervision. Performance analysis demonstrates the high efficiency of our construction.