An Efficient Non-Blockchain-Based Self-Sovereign Identity System Using a Threshold-Multisignature

The absence of a unified identity layer on the Internet has led to frequent cybercrimes and fraud, posing significant security risks. Although Self-Sovereign Identity (SSI) offers a unified identity layer, its reliance on blockchain as the root of trust introduces challenges related to redundancy and portability. Moreover, existing non-blockchain-based SSI systems are vulnerable to issues such as dead attacks during key rotation and impose high storage demands on distributed nodes. To address the above problems, we propose a novel non-blockchain-based SSI system. Our solution features an innovative key rotation method that pre-commits to the next keys without revealing them, mitigating the risk of keychain forks caused by dead attacks. Additionally, we employ threshold-multisignature aggregation to ensure system security in the presence of Byzantine nodes, while significantly reducing storage overhead by minimizing the need for redundant cryptographic materials. Finally, a prototype implementation of our scheme demonstrates improved efficiency compared with other threshold-multisignature schemes and propagation protocols, without compromising security.