An image encryption scheme based on irregularly decimated chaotic maps

An image encryption scheme provides means for securely transmitting images over public channels. In this work, we propose a robust shuffling-masking image encryption scheme based on chaotic maps. The shuffling phase permutes square blocks of bytes using a 3-dimensional chaotic cat map coupled with a zigzag scanning procedure. The masking phase then scrambles b-byte blocks of the shuffled image with combined outputs of three 1-dimensional chaotic skew tent maps, in such a way that the masking of every block is influenced by all previously masked blocks. Empirical results show that while the suggested scheme has good running speed, it generates ciphered images that exhibit (i) random-like behavior, (ii) almost flat histograms, (iii) almost no adjacent pixel correlation, (iv) information entropy close to the ideal theoretical value. Furthermore, this scheme has a large key space, strong sensitivity to the secret key, and is robust against differential attacks. On the basis of these results, this scheme can be regarded as secure and reliable scheme for use in secure communication applications. (C) 2013 Elsevier B.V. All rights reserved.