Abstract: Data may be tampered with by illegal elements during storage, leading to security issues such as data leakage and damage. In order to ensure the security of data and further improve the anti tampering ability of cloud data, an anti tampering storage algorithm for multi blockchain cloud data is proposed. By analyzing the structure of multi blockchain networks, a cloud data distributed storage architecture based on blockchain technology is designed. A cloud data access control model is designed through the data layer, application interaction layer, contract layer, and functional layer to improve the security of distributed cloud data storage. During the data encryption and decryption process, Hash algorithm and asymmetric encryption algorithm are combined to encrypt and decrypt the combined data of “random number+cloud data冶, to avoid the phenomenon of node private key leakage, cloud data being replaced and forged. The experimental results show that the encryption and decryption processing time of the proposed algorithm is maintained within 25 ms, the probability of successful attack is less than 40%, and the data is not easily tampered with during transmission.

Key words: blockchain technology, distributed data storage, cloud data, data encryption, anti tamper storage