Anti-collusion attack image retrieval privacy protection scheme for ASPE

The existing algorithm based on Asymmetric Scalar-Product-Preserving Encryption (ASPE) realizes privacy protection in image retrieval under cloud computing. But due to untrustworthy cloud service providers and retrieval users during retrieval and the existence of an external adversary, it cannot resist the collusion attack of malicious users and cloud servers, which may lead to the leakage of image data containing sensitive information. Aiming at multi-user scenarios, an Anti-collusion attack image retrieval privacy protection scheme for ASPE is proposed. First, the scheme uses proxy re-encryption to solve the problem of image key leakage caused by transmitting private keys to untrusted users. Second, the feature key leakage problem between the cloud service provider and the retrieval user due to collusion attacks is solved by adding a diagonal matrix encryption at the client side. Finally, linear discriminant analysis is used to solve the problem of retrieval accuracy drop caused by dimensionality reduction when locality sensitive hashing is used to construct an index. The security analysis proves that the scheme is safe and effective and that it can not only resist collusion attacks from cloud service providers and untrusted users, ciphertext-only attacks, known background attacks and known plaintext attacks, but also realize protection of images and private keys during the process. Experimental results show that under the premise of protecting image privacy and ensuring retrieval efficiency, the retrieval accuracy of the proposed scheme in the ciphertext domain and that in the plaintext domain are only about 2% different. © 2023 Science Press. All rights reserved.