A three-step Bc-optimistic blockchain-based contract signing protocol

Abstract This work addresses the problem of blockchain-based contract signing. We introduce the notion of a protocol step, which is a key concept that facilitates uniform and fair comparisons among existing protocols (especially in light of a claim regarding the minimal step count of a previous proposal that is not substantiated upon closer analysis). We conduct a comprehensive evaluation of all prior protocols with respect to both mandatory and optional security requirements. On the basis of this analysis, we propose a novel contract signing protocol that, under optimistic execution, does not invoke any on-chain functions and requires only three protocol steps to be completed, thus identifying it as the most efficient solution. A security analysis is presented, thus demonstrating that the proposed protocol satisfies all the mandatory security requirements. We also discuss how the generated signatures and evidence can be aligned with legal and regulatory frameworks. These results confirm the feasibility and efficiency of our approach.