LSB++: An improvement to LSB+ steganography

The Least Significant Bit (LSB) substitution is an old and simple data hiding method that could almost effortlessly be implemented in spatial or transform domain over any digital media. This method can be attacked by several steganalysis methods, because it detectably changes statistical and perceptual characteristics of the cover signal. A typical method for steganalysis of the LSB substitution is the histogram attack that attempts to diagnose anomalies in the cover image´s histogram. A well-known method to stand the histogram attack is the LSB⁺ steganography that intentionally embeds some extra bits to make the histogram look natural. However, the LSB⁺ method still affects the perceptual and statistical characteristics of the cover signal. In this paper, we propose a new method for image steganography, called LSB⁺⁺, which improves over the LSB⁺ image steganography by decreasing the amount of changes made to the perceptual and statistical attributes of the cover image. We identify some sensitive pixels affecting the signal characteristics, and then lock and keep them from the extra bit embedding process of the LSB⁺ method, by introducing a new embedding key. Evaluation results show that, without reducing the embedding capacity, our method can decrease potentially detectable changes caused by the embedding process.