A High Capacity Gray Code Based Security Scheme for Non-Redundant Data Embedding

This paper proposes a double layer technique, used to improve the level of security by deploying both cryptography and steganography. The Blowfish algorithm was chosen for the cryptography layer, while an enhanced steganography technique was used for the steganography layer. Embedding is done according to a flag that avoids embedding a redundant bit by highlighting whether one or two bits are embedded per pixel, depending on the redundancy. If the bit to be embedded is similar to the already existing bit, the next bit is embedded in the 7th significant bit position and the flag is modified. The flag position varies depending on whether the pixel is odd or even and its values vary for each color plane. In the steganography layer, a Gray code sequence is used to scramble the order of the pixels in which data will be embedded. This is utilized to make it insurmountable for a third party to detect. 13 different performance measurements are computed and evaluated, to ensure that the image quality remains preserved. The proposed scheme is compared with its counterparts in the literature, in terms of mean square error (MSE), structure similarity index (SSIM), peak signal to noise ratio (PSNR), structural content (SC), maximum embedding capacity, extraction time and maximum Difference. Outstanding numerical results are achieved, showing superiority of the proposed schemes in terms of performance, capacity, and security.