This study proposes a cooperative blockchain privacy data interaction and storage scheme integrating secure multi-party computation (SMPC) to address the consistency and security problems of blockchain privacy data in on-chain and off-chain interactions. Through the combination of layered architecture design (data storage layer, open sharing layer, and arbitration organization layer) and cryptographic techniques (threshold Paillier encryption, smart contract key management), the scheme realizes the “usability and invisibility” and controllable ownership of private data. The program adopts IPFS to store encrypted data under the chain and records the hash address through the blockchain, which effectively solves the problem of limiting the storage capacity on the chain. At the same time, it introduces a threshold decryption mechanism, which requires at least t participants to collaborate on decryption to prevent internal malicious behavior and single point of failure. The experimental results show that compared with the traditional DSSA protocol and Paillier homomorphic encryption scheme, this scheme has significant advantages in computational cost (reduced to 0.35 for vector dimension 5000), communication cost (reduced to 68.81), and operational efficiency (time consumed is 504.81ms for modulus 1024bit), which provides theoretical support for efficient and secure interactions of private data. It provides theoretical support and practical reference for efficient and secure interaction of private data.
