Length-preserving bit-stream-based JPEG encryption

Abstract

We propose a new method to encrypt baseline JPEG bit streams by selective Huffman code word swapping and coefficient value scrambling based on AES encryption. Furthermore, we show that our approach preserves the length of the bit stream while being completely format-compliant. In contrast to most existing approaches, no recompression is necessary as the encryption is applied directly to the bit stream. In addition, we assess the effort required for brute-force and known-plaintext attacks on pictures encrypted with our approach, showing that both are practically infeasible.

Building a post-compression region-of-interest encryption framework for existing video surveillance systems

“…A more detailed description of all encryption steps as well as a thorough security analysis can be found in [1,43]. Note that, although Auer et al [1] describe a full-picture encryption approach, their security analysis is limited to single blocks, so it can be used for our modified approach as well.…”

“…We use this replacement attack on our proposed approach and the one by Unterweger and Uhl [43]. The latter performs AC encryption in the same way as the approach by Auer et al [1], but does not encrypt DC coefficient differences, i.e.…”

“…Fig. 11 Effects of a replacement attack on our proposed encryption approach (a, c) versus the encryption approach by Unterweger and Uhl [43] …”

Region of interest signalling for encrypted JPEG images

“…In this Section, we discuss several design choices for encodings, aiming at listing a set of practically useable encodings to be evaluated in Section 4. As most state-of-the-art encryption approaches for JPEG operate on a block [15] or iMCU (interleaved Minimum Coding Unit, multiple luminance and the corresponding chrominance blocks) level [22], coordinates are limited to iMCU granularity. Note that this limitation is also imposed -often self-imposed [3] -on format-independent encryption approaches which operate in the image domain.…”

“…Availability: The guarantee that the proposed method will work on every JPEG picture 4. Length-preservation: The guarantee that the picture's file size does not change (suitable for lengthpreserving encryption methods like [22]) Furthermore, the capacity, i.e., the amount of storable bits, of each signalling method is given. Note the capacity of some of the proposed methods depends on the picture and/or its metadata.…”