A secure image encryption algorithm based on hyper-chaotic and bit-level permutation

In this paper, an encryption algorithm based on hyper-chaotic system and bit-level permutation is proposed. Firstly, the forward diffusion method based on two-dimensional XOR operation is used to diffuse the image. Then, the scrambled images are arranged and scrambled in different directions. Finally, the ciphertext image is obtained by two-dimensional XOR backward diffusion. A novel bit-level permutation used in this algorithm, which not only expands the bit levels in different directions, but also exchanges the values between the bit bevels. It improves the efficiency and security of encryption. The diffusion random matrix is generated by hyperchaotic system. The initial value and control parameters of hyper-chaotic system are calculated by Secure Hash Algorithm 256 (SHA-256) function, which increases the key space and improves the plaintext sensitivity of the algorithm. On the one hand, the simulation results show that the scheme has high security and better plaintext sensitivity and key sensitivity. On the other hand, compared with the related algorithms, it can better resist statistical attacks and differential attacks.