Image encryption algorithm using S-box and dynamic Hénon bit level permutation

For the secure transmission of data through the medium of internet, images have significant importance. Image encryption provides secure transmission of images by converting recognizable form of image into an unrecognizable form. Chaos is considered as a natural required ingredient for cryptography applications, by providing unpredictability, sensitivity of initial state and erogodicity. Therefore from the last decade, a number of chaos-based cryptosystems have been developed for the protection of transmitted images’ content. In this paper, a chaos based algorithm is developed and experimented on six different standard empirical images. The proposed cryptosystem is based on substitution-permutation network (SPN) with cipher block chaining (CBC) mode of operation. A novel algorithm is proposed for the construction of substitution box by using chaotic sine map, which is applied on a block-input of bytes, followed by a permutation based on discretized Hénon map, which is applied on a block-input of bits instead of bytes. The hyper chaotic Lü system, which is nonlinear and produces discrete values with long orbits, is used as pseudorandom generator to set new values to control parameters of discretized Hénon map for bit-permutation for each block. Moreover, proposed bit-permutation is applied by a matrix formulation which accelerates the bit permutation process for a block-input. Security analysis and results obtained from simulations show that cryptosystem is good resistant to various well-known attacks and have good key space therefore is reliable for secure transmission of images.