Security-enhanced interference-based optical image encryption

Interference-based optical image encryption has triggered much current attention due to its marked advantages, such as non-iterative operation. Although interference-based optical image encryption is an effective approach, cryptosystem security is still a great concern from a cryptanalysis point of view and higher security is always desirable. In this paper, we propose a novel method to enhance the security for conventional interference-based optical image encryption in the fractional Fourier transform (FrFT) domain. A series of random and fixed phase-only masks is used in the optical paths, and subsequently interference principle is applied to extract two phase-only masks (i.e., ciphertexts) during image encryption. Feasibility and effectiveness of the proposed method are demonstrated by computer simulations.