Abstract:

User privacy security is the primary problem in the popularization and application of cloud services, while the fully homomorphic encryption scheme is the key technology to solve it. The integer fully homomorphic encryption scheme is the main method at present, and its operation is limited to addition and multiplication, which limited the application field of the scheme. At the same time, the low efficiency and poor security of encryption and decryption make integer fully homomorphic encryption scheme not suitable for the cloud service environment. In order to solve the problems above-mentioned, a full homomorphic encryption scheme over real number suitable for cloud service environment is proposed in this paper. Based on the mathematical theory basis of compound homomorphism, this scheme applies the fully homomorphic encryption technology to the real number range through the analog module operation, and adds subtraction and division on the operation, which not only enriches the kinds of operations, but also effectively extends the data encryption scope and the application field of fully homomorphic encryption. Finally, the proposed scheme is applied to the medical test data set used in the privacy protection field, and compared with the fully homomorphic encryption scheme applied to n bits and the faster fully homomorphic encryption scheme over integer in the encryption and decryption time and operation time. The experimental result shows that the scheme can extend the encryption scope more effectively, reduce the time of data encryption and decryption in cloud service environment and has high security. The real fully homomorphic encryption scheme is suitable for cloud service environment.

Key words: privacy security, cloud service, fully homomorphic encryption, real number, similar module (Rmod)