A digital image encryption algorithm based a composition of two chaotic logistic map

The chaos based cryptographic algorithms have suggested several advantages over the traditional encryption algo-rithms such as high security, speed, reasonable computa-tional overheads and computational power. This paper introduces an efficient chaos-based stream cipher, com-posing two chaotic logistic maps and a large enough exter-nal secret key for image encryption. The external secret key is used to derive the initial conditions for the chaotic maps, and is employed with the two chaotic maps to con-fuse the relationship between the cipher image and the plain image. In the encryption phase, the pixels are en-crypted using an iterative cipher module based feedback and data-dependent inputs mechanism for mixing the cur-rent encryption parameters with previously encrypted in-formation. To make the cipher more robust against any attack, the secret key is modified after encryption of each pixel of the plain image. The results of several experi-mental, statistical analysis and key sensitivity tests show that the proposed image encryption scheme provides an efficient and secure way for real-time image encryption and transmission