An Efficient Chaos-Based Feedback Stream Cipher (ECBFSC) for Image Encryption and Decryption

The chaos based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. Towards this direction, this paper presents an efficient chaosbased feedback stream cipher (ECBFSC) for image cryptosystems. The proposed stream cipher is based on the use of a chaotic logistic map and an external secret key of 256-bit. The initial conditions for the chaotic logistic map are derived using the external secret key by providing weightage to its bits corresponding to their position in the key. Further, new features of the proposed stream cipher include the heavy use of data-dependent iterations, data-dependent inputs, and the inclusion of three independent feedback mechanisms. These proposed features are verified to provide high security level. A complete specification for the proposed ECBFSC is given. Several test images are used for inspecting the validity of the proposed ECBFSC. The results of several experimental, key space analysis, statistical analysis, and key sensitivity tests show that the proposed ECBFSC for image cryptosystems provides an efficient and secure way for real-time image encryption and transmission from the cryptographic viewpoint.