Optical Encryption and Authentication Based on Phase Retrieval and Sparsity Constraints

Complex holographic schemes are usually required to obtain complex-valued encrypted images that are used for verification in previously proposed authentication approaches based on photon-counting imaging and double-random-phase encoding (DRPE). In this paper, we propose an optical information encryption and authentication system by integrating the classical optical DRPE with a modified iterative phase retrieval algorithm using 2-D median filtering. Only the intensity of the encrypted data needs to be recorded during the optical encryption process, and a private phase distribution is generated by combining iterative phase retrieval and 2-D median filtering. Sparse representation for the phase distribution, but not for a complex-amplitude distribution, is used for decryption and verification. Simulation results demonstrate the validity of the proposed approach.