Hybrid cryptosystem based on diffraction transfer function and phase-truncated Fourier transform encryption

A hybrid cryptosystem based on phase-truncated Fourier transform (PTFT) encryption and diffraction transfer function is designed. The designed cryptosystem cannot be decrypted by phase-retrieval-based attacks to which conventional phase-truncated Fourier transform cryptosystems are proven vulnerable. Compared with conventional PTFT encryption, the encryption process of this proposed cryptosystem needs no extra devices. With the help of Rayleigh–Sommerfeld diffraction theory, the inverse diffraction optically is realized and the decryption process can be performed using a liquid crystal spatial light modulator. Unlike conventional PTFT cryptosystem, no useful information can be retrieved in case of lacking any of ciphertext, private keys and diffraction parameters. The optical setup and numerical simulation results are provided to verify the effectiveness, security and robustness of proposed hybrid cryptosystem.