A Secure Image Communication Scheme based on combination of Compression, Cryptography and Steganography

In this paper we propose a new technique for secret communication of a digital image through a network exposed to attackers. The security is achieved by a combination of two popular information security techniques: Cryptography and Steganography. We have used a modified version of AES for encryption which uses a keystream generator(W7) and four techniques for steganography (one in spatial and three in frequency domain) which resist some typical statistical attacks. Before encryption we have used JPEG compression technique to compress the image. Huffman codes obtained in the entropy coding step are encrypted using AES and hidden in a cover. The stego image is hence transmitted. Introduction of compression reduces the amount of data to be encrypted and hence the encryption time. Modified AES with keystream generator improves the security of the system and steganography adds another level of secrecy. We have also tried to compare the performance of the four steganographic techniques.