Abstract:The security and efficiency of cloud data storage are urgent issues to be solved in cyberspace security. Therefore, a new ciphertext retrieval model is proposed in the study, and on this basis, the ElGamal homomorphic cipher algorithm and SM4 block cipher algorithm are used to design a cloud ciphertext storage and retrieval solution based on hybrid homomorphic encryption. The retrieval solution can ensure data security during data uploading, retrieving, and downloading and can be applied to personal cloud USB drives and other application scenarios. Moreover, the correctness and safety of the scheme are analyzed and proved through experiments. The experimental results reveal that the scheme can assure correct retrieval results with high efficiency while ensuring data security.