J4: JPEG Steganography using Dual Histogram Compensation

Steganography is the art of secret communication between two parties that not only conceals the contents of a message, but also its existence. Steganalysis attempts to detect the existence of embedded data in a steganographically altered cover file. Many algorithms have been proposed, but so far each has had some weakness that has allowed its effects to be detected, usually through first or second order statistical analysis of the image. In this paper, we propose a new approach to JPEG steganography that provides good stealthiness with global and dual histogram restoration. Our algorithm, named J4, is a new steganographic technique that improves on our previous system, J3. J4 uses dual histogram restoration along with matrix encoding to minimize detection by first as well as second order steganalysis. Existing blind steganalysis tests performed on J4 shows that it has a detection rate of 50-60% at 0.05-0.1 bit per non-zero coefficient (bpnz), as compared to 80-90% for F5, OutGuess, Steghide, MB1 and PQ. Since 50% detection rate is classified as random guess using a SVM classifier, J4 would be an ideal candidate for a steganographic algorithm. keywords: Steganography, J4, Dual-Histogram Compensation, Information Hiding, JPEG Steganography, Steganalysis, Matrix Encoding.