A Privacy-Preserving Image Retrieval Scheme Using Secure Local Binary Pattern in Cloud Computing

The rapid growth of digital images motivates organizations and individuals to outsource image storage and computation to the cloud. However, the defenseless upload will raise the risk of privacy leakage while the simple encryption would impede the efficient usage of data. In this paper, we propose a privacy-preserving image retrieval scheme, in which the images are encrypted but similar images to a query can be efficiently retrieved from the encrypted images. Specifically, the image content is protected by big-block permutation, 3 ×3 block permutation within big-blocks, pixel permutation within 3 ×3 blocks, and polyalphabetic cipher. The use of polyalphabetic cipher improves security and causes no degradation in terms of retrieval accuracy as the substitution tables are generated by the order-preserving encryption. In this way, secure Local Binary Pattern (LBP) features can be directly extracted as the local features from the encrypted big-blocks, which is efficient as there is no communication between the cloud server and image owners to do so. The secure local LBP features are used to generate the feature vector for each image by the bag-of-words model. Finally, the similarity among the encrypted images is measured by the Manhattan distance of such feature vectors. The security analysis and experimental results demonstrate that the proposed scheme outperforms the main existing schemes in terms of security and retrieval accuracy.