Bit-level image encryption algorithm based on random-time S-Box substitution

To solve the shortcomings of traditional cryptography such as 3DES, AES and SM4 in encrypting multimedia information, we proposed a bit-level image encryption algorithm based on chaos and S-Box. First, we constructed a 3D discrete memristor-based chaotic map (3D-MCM), which is hyperchaotic, and has ergodicity and better randomness in a larger parameter interval, then based on it, we constructed three S-Boxes with larger key space and without weakness. Furthermore, we applied the 3D-MCM and S-Boxes to design an encryption algorithm, whose novelty is that each half-pixel is substituted with a half-pixel substitution box (HPS-Box) before S-Box substitution with random times. Experimental and security analysis results demonstrated the effectiveness of the proposed 3D-MCM and S-Box in image encryption scheme.