A Searchable Encryption Scheme for Blockchain-Based Digital Twins

With the widespread adoption of digital twin (DT) technology in cross-domain data sharing scenarios, ensuring secure and efficient search over encrypted data has become a significant challenge. This paper proposes a blockchain-based searchable encryption scheme tailored for digital twins, supporting privacy-preserving keyword search, verifiable data access, and decentralized trust establishment. The scheme collects real-time data streams from digital sensors and devices to construct unified digital twin records for intelligent analytics and decision-making. The scheme integrates lightweight searchable encryption with blockchain-based trapdoor delegation and ciphertext-level indexing, enabling secure and low-complexity keyword matching. By introducing a delegated trapdoor mechanism, users can authorize repeated keyword queries via a single token, thereby minimizing communication and computational costs. Additionally, a blockchain-driven key generation protocol based on distributed voting eliminates reliance on centralized authorities and ensures transparent, auditable key management. Moreover, encrypted records are stored in IPFS, resolving the storage limitations of blockchain and preserving verifiable data availability. The trapdoor delegation records and result verification parameters are committed on-chain, enabling query correctness checking and traceable access control. Under the CI and TI security models, the proposed scheme is formally proven to achieve ciphertext indistinguishability and trapdoor privacy, providing resistance to adaptive insider keyword guessing attacks. Compared with existing schemes, it offers stronger privacy guarantees with lower overhead, supporting scalable and secure digital twin data sharing.