An efficient and secure Two-party Adaptor Signature Based on SM9 Signature

Adaptor signatures, a novel cryptographic primitive extended from standard signatures, provide an efficient and cost-effective solution to blockchain’s scalability. By embedding witness of a preset hard relation within the pre-signature value, adaptor signatures ensure that only those who know the witness can transform the pre-signature into a complete signature. This technique has been widely applied in payment channels and atomic swaps. In this work, we propose a two-party adaptor signature scheme based on the SM9 algorithm to enhance the scalability of identity-based blockchains while mitigating the risk of private key leakage. We prove the security of the scheme within the random oracle model. Additionally, we analyze the computational and communication overheads of our scheme compared to existing two-party adaptor signature schemes, demonstrating that it offers higher computational efficiency. Finally, we explore the potential application of our scheme in atomic swaps.