Research on multiple-image encryption method using modified Gerchberg-Saxton algorithm and chaotic systems

A multiple-image encryption method based on a computer-generated phase-only hologram (POH) algorithm and chaotic systems is proposed. In the proposed method, first, a modified Gerchberg-Saxton (GS) algorithm is applied to transform the multiple-image into corresponding sub-sampled POHs. Then, the multiple POHs are combined using spatial division multiplexing (SDM). The combined hologram is then mapped into a digital image, and each pixel of the digital image is transformed by a chaotic system to improve security and form the final ciphertext. The modified GS algorithm is employed to generate a sub-sampled POH, which is a prerequisite for SDM. The adoption of SDM eliminates issues such as information leakage due to inter-image crosstalk and ensures the quality of decrypted images. The transformation based on a chaotic system leads to nonlinearity and unpredictability in the encryption process, which further increases the complexity of the encryption system. Numerical simulation demonstrates the security and feasibility of the proposed multiple-image encryption method.(c) 2023 Society of Photo-Optical Instrumentation Engineers (SPIE