The unified image encryption algorithm based on chaos and cubic S-Box

A new fast image cryptosystem was studied in this paper. The system employed the piecewise linear chaotic map and cubic S-box to generate key stream with excellent statistical characteristics for image encryption. Unlike most existing image cryptosystems, the proposed image cryptosystem possessed identical encryption process and decryption process, which both include one key stream generator, two plaintext-unrelated diffusion operations, one plaintext- related confusion operation and one 180-degree matrix rotation operation. To measure the visual difference between the two images of the same size, a new index named BACI (blocked average changing intensity) was presented as the index of sensitivity analysis. Simulate test and comparative analysis show that the proposed image cryptosystem has the characteristics of large key space, fast encryption/decryption speed, high sensitivity, good statistical properties of cipher-text, and etc. The proposed cryptosystem is an available alternative scheme for the practical secure communications.