Auditable cross-domain data sharing via threshold secret sharing and zero-knowledge proofs

Cross-domain data sharing in decentralised environments faces persistent challenges related to confidentiality, auditability, and trust decentralisation, particularly when data transmission relies on centralised intermediaries or single proxy entities. To address these issues, this paper proposes a blockchain-enabled auditable data sharing scheme that integrates threshold secret sharing with non-interactive zero-knowledge proofs. In the proposed framework, the encrypted file fragments and secret key shares are decentralised across multiple blockchain nodes using threshold cryptography, preventing any single entity from reconstructing the encryption key or unilaterally performing ciphertext transformations. Zero-knowledge proofs are employed to publicly verify the correctness of the transmission and sharing operations without disclosing plaintexts, secret keys, or sensitive metadata, while the blockchain records verifiable proofs to support tamper-evident auditing. Security analysis shows that the scheme achieves confidentiality, collusion resistance, and verifiable correctness under standard cryptographic assumptions.Experimental evaluations indicate that the proposed scheme incurs acceptable computational and on-chain overhead, suggesting its feasibility in decentralised and cross-domain data sharing scenarios.