Semi-symmetric cryptosystem for complex-valued object via single-shot ptychography and random modulus decomposition

A semi-symmetric optical cryptosystem for a complex-valued object via single-shot ptychography (SSP) and random modulus decomposition (RMD) is proposed. The decryption keys are not thoroughly identical to the encryption keys in this semi-symmetric cryptosystem. Owing to the complementarity between SSP and RMD, the proposed cryptosystem is able to encrypt the complex-valued object and resist the brute-force attack simultaneously. The structural fault tolerance ensures the high experimental feasibility of the cryptosystem. Meanwhile, the large key space and the destruction of partial encryption keys enable the cryptosystem to be robust against various attacks, including brute-force attack and iterative-algorithm attack. Further, several security-enhanced methods are proposed. Opto-digital experiments have been performed to verify the effectiveness of the proposed cryptosystem. Semi-symmetric cryptosystems will surely bring profound illumination to the field of optical security.