Multi-user Fully Homomorphic Encryption Scheme Based on Policy for Cloud Computing

Cloud computing, a modern application that is very commonly utilized, has garnered considerable interest from researchers and developers. Data privacy security is the most urgent issue related to cloud computing. Studies have shown that fully homomorphic encryption (FHE) technology, which is related to traditional encryption and ciphertext evaluation, is an effective way of securing privacy in the cloud. This study proposes a policy-based, multi-user, FHE algorithm (PB-MUFHE) that accounts for user diversity in the cloud environment, in which, the encrypted data is set under an appropriate access policy, the key to which is a set attribute. Not only is homomorphic evaluation supported for ciphertexts among several users, but also fine-grained access control and sharing between users are supported. The security of the PB-MUFHE scheme was tested based on learning with errors (LWE) problems, and IND-CPA security analysis in the generic bilinear group random oracle model further verified the proposed algorithm's effectiveness. Performance assessment demonstrated that, PB-MUFHE can efficiently implement fully homomorphic evaluation of ciphertext, and effectively support access control and shared multi-user capability.