Abstract: With the rapid development of blockchain technology, hundreds of different blockchain platforms have emerged. The heterogeneous characteristics of different blockchain platforms have brought new challenges:how to perform cross-chain identity authentication between heterogeneous blockchain systems to ensure the security of cross-chain interactions? Due to the heterogeneity of the underlying technologies and cryptographic systems used by different blockchain platforms, existing identity authentication technologies struggle to adapt to cross-chain identity authentication and mostly suffer from issues such as single-point failure risks, insufficient privacy protection, and low verification efficiency. In response to the above problems, this paper proposes a decentralized cross-chain identity authentication scheme based on a relay chain, which innovation is reflected in three aspects:firstly, by combining relay chain technology with decentralized identity authentication technology, a decentralized identity management system is constructed to achieve decentralized cross-chain identity authentication; secondly, privacy protection verification of identity credentials is realized based on zero-knowledge proof, effectively guarding against privacy tracing risks in cross-chain interactions; finally, a relay chain dynamic sharding protocol is designed to improve system throughput by processing verification tasks in parallel. Experimental evaluation shows that this scheme has complete functions and high efficiency, providing a feasible path for the secure interoperability of the cross-chain ecosystem.

Key words: decentralized identity authentication, cross-chain, relay chain, blockchain sharding, zero-knowledge proof