A Chaotic System Based Image Encryption Scheme with Identical Encryption and Decryption Algorithm

A new symmetric key image encryption scheme based on hyper-chaotic Lorenz system is proposed. The encryption process and the decryption process are identical in the proposed scheme. They both include two diffusion operations, one plaintext-related scrambling operation and three matrix rotating 180 degrees operations. The hyper-chaotic Lorenz system is employed to generate the secret code streams to encrypt the plain image, and to implement the diffusion process with XOR operation. The plaintext-related scrambling is used in this scheme to make different plain images correspond to different secret code streams even when the secret keys are the same, so that the scheme can fight against the chosen/known plaintext attacks. Simulation results show that the proposed scheme has the merits of high encryption speed, large key space, strong key sensitivity, strong plaintext sensitivity, good statistical properties of cipher-text, and etc., and can be used in practical communications.