Fair Contract Signing Model Based on Blockchain and VES Algorithm

Abstract

The Verifiably Encrypted Signature (VES) algorithm is a common method for solving the fair exchange of digital signatures. It uses an offline trusted third party (TTP) as an adjudicator, playing a role similar to a guarantor. However, the fairness of signature exchange in traditional methods depends on the neutrality of the adjudicator, and there is a possibility that the adjudicator and a party may collude to commit fraud. To address this issue, this paper designs a fair signature exchange scheme without the TTP based on blockchain and VES algorithm, thus solving the problem of the trust crisis with adjudicator. At the same time, current blockchain smart contract do not support the generation and verification of the VES. As a result, this paper introduces the blockchain oracle to delegate these operations to off-chain execution. Finally, we achieve a closed-loop solution for a Fair Contract Signing model, this scheme utilizes smart contracts and blockchain oracle to complete all aspects of digital signature exchange.