An Adaptive Pseudorandom Stego-crypto Technique for Data Communication

To provide security in data communication networks various forms of cryptographic and steganographic algorithms have been proposed. Though both of these techniques serve the same purpose i.e. to secure data but have some drawbacks. Using cryptography might raise some suspicion whereas in steganography the distortion in cover can attract an adversary. The combinations of the two as proposed by various researchers can be very fruitful in terms of brute force search time and robustness against attacks. A popular method of combination is using pseudorandom Least Significant Bit (LSB) substitution along with stream cipher or block cipher. The problem with pseudorandom LSB substitution technique is with the random pixel selection process. It inserts the cipher text on randomly chosen pixels using random interval method having certain period. Now if this period of random interval number generations is large, it increases time complexity. On the other hand if it is too low then the cipher text will not be evenly distributed in all the colour planes. This paper proposes an adaptive method on the basis of size of secret data for random pixel selection for data embedding. The results show that using such an approach not only increases brute force search time but also reduces the time complexity of the overall process.