  Content-Based Image Retrieval (CBIR) techniques have been widely researched
and in service with the help of cloud computing like Google Images. However,
the images always contain rich sensitive information. In this case, the privacy
protection become a big problem as the cloud always can't be fully trusted.
Many privacy-preserving image retrieval schemes have been proposed, in which
the image owner can upload the encrypted images to the cloud, and the owner
himself or the authorized user can execute the secure retrieval with the help
of cloud. Nevertheless, few existing researches notice the multi-source scene
which is more practical. In this paper, we analyze the difficulties in
Multi-Source Privacy-Preserving Image Retrieval (MSPPIR). Then we use the image
in JPEG-format as the example, to propose a scheme called JES-MSIR, namely a
novel JPEG image Encryption Scheme which is made for Multi-Source content-based
Image Retrieval. JES-MSIR can support the requirements of MSPPIR, including the
constant-rounds secure retrieval from multiple sources and the union of
multiple sources for better retrieval services. Experiment results and security
analysis on the proposed scheme show its efficiency, security and accuracy.
