OPTICAL IMAGE ENCRYPTION FOR INFORMATION SECURITY

Abstract

This thesis proposes novel and advanced image encryption and authentication schemes based on various optical techniques including double-random phase-encoding (DRPE) in Fourier domain, phase-shifting (PS) and joint transform correlator (JTC). Numerical simulation is carried out to validate the feasibility and effectivenss of proposed schemes, and some potential optical implementations for proposed algorithms are presented. In addition, cryptoanalysis on some existing schemes combining phase-truncated Fourier transform (PTFT) and other techniques, and schemes based on vector decomposition techniques is proposed. In the cryptoanalysis, the security strength of these schemes is evaluated, and their inherent drawbacks and weaknesses are released. Based on the security analysis, special attacks based on iterative phase-retrieval process with various constraints are proposed to crack these cryptosystems.