Image encryption algorithm based on multi-bit superposition and optical chaos

Abstract

Aiming at the problem that the leakage of single-layer key encryption may lead to the theft of image information, we propose an image encryption algorithm based on multi-bit superposition and optical chaos. The generated optical chaotic sequence is used to encrypt the encrypted image together with the user input key. In the scrambling stage, the 3D-cat map is used to encrypt the bit plane, and the multi-bit superposition method is used to encrypt the key space between the bit planes again by using the sub-block internal and external encryption methods. In the diffusion stage, the Logistic-tent map is used to diffuse the scrambling image to generate the ciphertext image, and the optical chaotic waveform is used as the carrier to mask the ciphertext image information in the transmission process. At the recipient, the ciphertext image information is obtained through the synchronized optical chaotic waveform, and the image is decrypted by using the synchronized optical chaotic sequence and the key transmitted through the secure channel. If only one of the two cannot decrypt the image, the security of image transmission is improved. The simulation results show that the correlation of adjacent pixels of the image encrypted by the algorithm is close to zero, the gray histogram is evenly distributed, the pixel change rate, the normalized average change intensity and the block average change intensity are close to the ideal value, and the sensitivity of the plaintext is further enhanced, which can effectively resist statistical attacks, differential attacks and exhaustive attacks.