Asymmetric optical image encryption based on an improved amplitude-phase retrieval algorithm

We propose a new asymmetric optical image encryption scheme based on an improved amplitude-phase retrieval algorithm. Using two random phase masks that serve as public encryption keys, an iterative amplitude and phase retrieval process is employed to encode a primary image into a real-valued ciphertext. The private keys generated in the encryption process are used to perform one-way phase modulations. The decryption process is implemented optically using conventional double random phase encoding architecture. Numerical simulations are presented to demonstrate the feasibility and robustness of the proposed system. The results illustrate that the computing efficiency of the proposed method is improved and the number of iterations required is much less than that of the cryptosystem based on the Yang-Gu algorithm.