Privacy-Preserving Digital Evidence Chain for Accounting Vouchers Based on Smart Contracts and Paillier Homomorphic Encryption

Abstract

Electronic accounting voucher deposits and cybersecurity audits face a contradiction between resistance to evidence tampering and data privacy protection. Using blockchain technology as a basis, the authors propose a solution framework that addresses both concerns. Under a dual-layer hash mapping architecture, original accounting vouchers are stored off-chain via the InterPlanetary File System, and digital fingerprints are anchored on the immutable ledger. Smart contract engines enforce a multi-signature state machine to ensure accounting voucher traceability from generation to archiving. Paillier homomorphic encryption supports direct computation on ciphertext, enabling continuous consistency checks between accounts and accounting vouchers without decrypting raw data. Experimental results showed that on-chain storage overhead was reduced by 99.08%, audit latency reached 12.4 s under a workload of 5,000 transactions per second, and no raw data were exposed throughout the process. This framework provides forensic-ready support for secure electronic accounting voucher management.