Privacy-Preserving Content-Based Image Retrieval Using Compressible Encrypted Images

Abstract

In this paper, we propose a novel content basedimage retrieval scheme allowing the mixed use of encrypted and plain images for the first time. In the proposed scheme, images are encrypted by a block-scrambling method developed for encryption-then-compression (EtC) systems. The encrypted images, referred to as EtC images, can be compressed with JPEG, as well as for plain images. Image descriptors used for the proposed retrieval is designed to avoid the effect of image encryption. As a result, the use of EtC images and the descriptors allows us to carry out retrieval of both encrypted images and plain ones. In an experiment, the proposed scheme is demonstrated to have the same performance as conventional retrieval methods with plain images, even under the mixed use of plain images and EtC ones.

A Privacy-Preserving Image Retrieval Scheme Using A Codebook Generated From Independent Plain-Image Dataset

“…In addition, some secret information is shared between the image owner and users [4], [11]. In contrast, in the second approach, descriptors are directly extracted from encrypted images without decryption by cloud providers [5], [12]- [16], and the image owner has no secret information that should be shared with users. The proposed scheme corresponds to this approach.…”

“…In this paper, we focus on EtC images, which are images encrypted by using a block-wise encryption method for EtC systems [21]- [24]. EtC images have almost the same compression performance as those of plain images but also enough robustness against various ciphertext-only attacks including jigsaw puzzle solver attacks [16], [25]- [28]. EtC images are generated by following the procedure as below (see Figs.…”

“…Extended SIMPLE descriptors (E-SIMPLEs) were proposed for image retrieval of EtC images, and high retrieval performances were reported in the conventional schemes [16]- [18]. In the proposed scheme, E-SIMPLEs are used as image descriptors, as well as conventional schemes.…”

A Privacy-Preserving Image Retrieval Scheme with a Mixture of Plain and EtC Images

“…However, there is the possibility of data leakage and unauthorized use by service providers because they are not trusted in general. Therefore, various privacy-preserving image identification [10] and retrieval [1]- [9] and processing schemes [11], [12] have been proposed.…”

“…In the proposed scheme, encryption-then-compression (EtC) images are used as compressible images [14]. For image-retrieval, extended SIMPLE descriptors [1]- [3] are used for avoiding the influence of image encryption. The proposed scheme was demonstrated to have the same retrieval performance as that of using plain images, even when using a mixture of encrypted and plain images.…”