ABSTRACT
This chapter analyzes the vulnerability of the original multi-chaotic systems-based image encryption scheme, and proposes the corresponding enhancement measures to defeat cryptanalysis. In order to achieve significant confusion and diffusion, a chaotic image encryption scheme typically includes two stages. The first stage is to permute all the pixels of an image as a whole by using a two-dimensional chaotic map, and the second stage is to change the entire pixel values of the permutated image sequentially. The image encryption processes, including chaotic variable creation, sorting chaotic sequences, column vertical shuffling, and row horizontal shuffling, are essentially similar to the original scheme. The chapter discusses a self-synchronizing method to solve the problem, whose name is derived from the self-synchronizing stream cipher in classical cryptography. In the original self-synchronizing stream cipher, the keystream is generated as a function of both the key and a fixed number of previous ciphertext/plaintext digits.
