A color image encryption technique using exclusive-OR with DNA complementary rules based on chaos theory and SHA-2

A novel color image encryption algorithm is proposed in this paper which utilizes SHA-256 hash function to modify the initial conditions and control parameters of chaotic system. Three channels of a color image called red, green and blue is arranged into one dimensional vector and sort according to chaotic sequence generated by Piecewise Linear Chaotic Map. Then this permuted array split into three parts where each represents a color channel and permuted again using Lorenz's chaotic system independently. After dual permutation, each pixel of every channel is independently encoded into Deoxyribonucleic Acid (DNA) bases chaotically. The novelty of algorithm is that the substitution of each pixel of a channel is achieved by Exclusive-OR operation with DNA complementary rules. This operation is repeated with multiple DNA rules in a sequence to some random number of times. This repetition of operation continues in a cycle. The selection of DNA rule in the beginning of this cyclic operation and continuation of operation is made reliant on Chen's chaotic sequence. The extensive simulated experimental results such as Key Sensitivity, Correlation, entropy, Number of Pixel Chang Rate (NPCR), Unified Average Cipher Intensity (UACI) scores prove that proposed algorithm has excellent encryption results obtained in just one round. This scheme has advantage over other encryption techniques that it has nice feature to resist transmission noise and loss of a part of an encrypted image.