Blockchain data secure sharing protocol based on threshold Paillier algorithm

With the development of Internet technology, secure storage and secure sharing of data have become increasingly important. Traditional data sharing schemes exist a series of problems including lack of security and low efficiency. In this paper, we construct a secure and efficient data sharing scheme based on threshold Paillier algorithm and blockchain technology, which achieves secure data storage and sharing without a third-party institution. Firstly, we propose a $(t,l)$ threshold Paillier blockchain data sharing scheme, which effectively prevents decryption failures caused by the loss of a single node’s private key. Secondly, we propose a combined on-chain and off-chain data storage scheme, we store the ciphertext on the cloud server and the ciphertext hash value on the blockchain, which not only ensures the integrity of the data but also solves the storage limitation problem on the blockchain. Finally, we use the simulation paradigm to prove the security of the scheme in the semi-honest model. The discussion results of the comparison and the analysis of performance show that the blockchain data security sharing scheme proposed in this paper has lower computational overhead and higher security than other similar schemes.