A fast image encryption algorithm based on chaotic map and lookup table
At present, a lot of image cryptosystems with permutation/diffusion architecture have been proposed. However, permutation and diffusion are considered as two separate stages, both requiring image-scanning to obtain pixel values. Moreover, because of extraction bits directly from the discrete state value of a chaotic map to generate the pseudorandom binary sequence, the quite time-consuming conversion from floating points to integers cannot be avoided in practical applications. In this paper, a novel image encryption scheme for both combining permutation–diffusion and avoiding conversion of floating-point number is proposed. Firstly, using the lookup table constructed and S-Box of AES, an efficient approach of generating the pseudorandom sequence required by diffusion is proposed. Then, the combined permutation/diffusion architecture is employed to shuffle and change the pixels. Theoretical analyses and computer simulations both confirm that the new algorithm has high security and is very fast for practical image encryption.
KeywordsImage encryption Cryptography Information security Chaotic map
Our sincere thanks go to the anonymous reviewers for their valuable comments. The work described in this paper was supported by the grants from the National Natural Science Foundation of China (No. 61003256), the Postdoctoral Science Foundation of China (2011M501391, 20110490082), the Natural Science Foundation of CQ CSTC (No. 2010BB2279) and the Program for excellent talents in Chongqing.
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