Traceable Multi-signature Scheme with Distributed Combiners and Lightweight Setup for Accountable Blockchain Transactions

Cross-chain asset bridges usually require the joint authorization of multiple nodes to execute transactions. Multi-signature, due to its ability to compress multiple signatures for the same message into a short signature, can be well applied to cross-chain asset bridges. The existing multi-signature schemes, however, based on distributed key generation (DKG) have obviously three vulnerabilities: the key generation stage incurs considerable interactive communications, a malicious centralized combiner enables to tamper with transaction content, and the signature scheme lacks the accountability function for signers. To solve these challenging issues, this paper constructs a new type of traceable multi-signature scheme TMDC (Traceable Multi-signature Scheme with Distributed Combiners). In this scheme, a fully decentralized key generation is exploited, where the signer node can independently generate public and private key pairs. To avoid the centralization of combiners, time-lock is used to limit the aggregation power of combiners. Once the time lock is unlocked, the combiner can no longer aggregate. Furthermore, TMDC designs the signature accountability algorithm and establishes a strong correlation mechanism between the signer’s behavior and the final multi-signature. Based on the specific properties above-mentioned, TMDC can be well applied to cross-chain asset bridges. TMDC not only enables distributed combiners to avoid the risks brought by only one combiner, but also can trace abnormal signers when the cross-chain asset bridge is attacked, significantly enhancing the security of the cross-chain asset bridge. Finally, after simultaneously implementing functions, TMDC still maintains a low communication and computational overhead. The verifying algorithm is superior to other related schemes, significantly enhancing the system efficiency.