Enhanced 1-D Chaotic Key-Based Algorithm for Image Encryption

In the past few years, a number of image encryption algorithms based on chaotic maps have been proposed. A recently proposed Chaotic-Key Based Algorithm (CKBA) is based on a one-dimensional Logistic map. However, it has been shown that the current CKBA model is unavoidably susceptible to chosen/known-plaintext attacks, and that the high security claims against ciphertext-only attack were overestimated by the authors. In addition, the chaotic Logistic map yields unbalanced output. In this paper we enhance the CKBA algorithm three-fold: (1)– we change the 1-D chaotic Logistic map to a piecewise linear chaotic map (PWLCM) to improve the balance property, (2)– we increase the key size to 128 bits, and (3)– we add two more cryptographic primitives and extend the scheme to operate on multiple rounds so that the chosen/known-plaintext attacks are no longer possible. The new cipher has much stronger security and its performance characteristics remain very good. A security analysis for the proposed system is performed and presented.