Optical single-channel cryptosystem based on thediscrete wavelet transform and chaotic Standardmap for multi-image

In this paper, an optical single-channel asymmetric cryptosystem based on the inverse discrete wavelet transform (IDWT) and chaotic standard map for multi-image in cyan-magenta-yellow-black (CMYK) mode is proposed. To the best of our knowledge, this is the first time that the color image in CMYK format is encoded into a real-valued two-dimensional (2D) format by the IDWT; thus, our scheme can be implemented in a single-channel step. In addition, we propose to generate the random phase mask based on the chaotic standard map. Due to the large key space and high efficiency of the chaotic standard map, the security level of the proposed scheme can be improved. The chaotic standard map is employed to generate the chaotic standard phase mask (CSPM). Then the encoded 2D image can be encrypted in the linear canonical transform domain based on the CSPM. Numerical simulation results are shown to verify the feasibility and effectiveness of our cryptosystem. In addition, our approach outperforms other relevant cryptosystems and can be extended to encrypt multiple color images directly.