In this article a novel image encryption method is proposed which is based on chaotic mapping and least squares. This algorithm uses a 256-bit key to encrypt the input image. The initial conditions and control parameters are obtained from this key. The proposed method is implemented on gray scale and color images, and consists of three basic steps: preprocessing, shuffling and masking. In the preprocessing phase the input image is encrypted by Xor operation and then shuffling is applied by substituting the location of input image pixels. Finally in the masking step, input image is encrypted by producing estimation by least square function and Xor operation. In order to evaluate the proposed method NIST test suit is used, furthermore other testing methods such as key space analysis, histogram test, entropy, and encryption quality, MAE, NPCR and UACI are used. Denote that this innovation depicts significant speed increase in image encryption methods based on chaotic mappings.
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