Analysis and Cryptanalysis of a Selective Encryption Method for JPEG Images

This paper addresses the protection of images. We address the problem of simultaneous selective encryption (SE) and image compression. The SE is done by using the Advanced Encryption Standard (AES) algorithm with the Cipher Feedback (CFB) mode one a part of the Huffman coefficients corresponding to the AC frequencies. For the compression we consider the JPEG algorithm. Our approach is done without affecting the compression rate and by keeping the JPEG bitstream compliance. In the proposed method, the SE is performed in the Huffman coding stage of the JPEG algorithm without affecting the size of the compressed image. We provide an experimental analysis of the proposed method when applied on still images as well as the results when applying SE in JPEG compressed images.