Steganalysis of LSB matching using characteristic function moment of pixel differences

Nowadays, many steganographic tools have been developed, and secret messages can be imperceptibly transmitted through public networks. This paper concentrates on steganalysis against spatial least significant bit (LSB) matching, which is the prototype of many advanced information hiding methods. Many existing algorithms deal with steganalysis problems by using the dependencies between adjacent pixels. From another aspect, this paper calculates the differences among pixel pairs and proves that the histogram of difference values will be smoothed by stego noises. We calculate the difference histogram characteristic function (DHCF) and deduce that the moment of DHCFs (DHCFM) will be diminished after stego bits are hidden in the image. Accordingly, we compute the DHCFMs as the discriminative features. We calibrate the features by decreasing the influence of image content on them and train support vector machine classifiers based on the calibrated features. Experimental results demonstrate that the DHCFMs calculated with nonadjacent pixels are helpful to detect stego messages hidden by LSB matching.