The Design Of Optical Information Security System Based On Phase-shifting Interferometry And Its Software Implementation

With the remarkably rapid development of Internet, computer and modern communication techniques, we have entered the information era and information security has been receiving more and more attention. Since B. Javidi and P. Refregier proposed the method of double random phase encoding technique in the4f setup in1995, optical information encoding and hiding has become a hot research area and attracted more and more researchers to the new field of optical information security. Optical information security system mainly adopts the principles and techniques of optical information processing (e.g. Fourier transform, hologram, diffraction, fractional Fourier transform, phase retrieval, polarization) to realize information encryption, hiding, embedding or extraction. Compared with the traditional information security system based on computer or electrical systems, optical information security systems have many significant advantages such as large capacity, high degree of freedom and inherent high-speed parallel processing ability for encryption and decryption.This thesis gives a systematic review of the developments of optical information security system, also briefly introduces some most-frequently used techniques of optical image encoding or digital watermarking. This thesis proposes some novel information security schemes based on phase-shifting interferometry and phase retrieval algorithm, combined with other processing techniques of related information security areas. The main research work in this thesis includes the following:(1) Combining the techniques of double random phase encoding and phase-shifting interferometry, an information hiding system is proposed, in which the information to be hidden can be encrypted into multiple interferograms. By choosing the appropriate weighting factor, the interferograms can be embedded in the host image. The secret information can be successfully extracted and decrypted by special phase-shifting reconstruction formula and inverse Fresnel diffraction transform. A software of information hiding system is designed by mixed programming between Visual C++and Matlab based in the Matcom software environments.(2) A robust image watermarking scheme based on phase-shifting interferometry (PSI) and singular value decomposition (SVD) is proposed, in which, a grayscale image watermark is encrypted into multiple interferograms using the techniques of double random-phase encoding (DRPE) and PSI. By choosing the appropriate weighting factor, the interferograms are embedded in the singular values of the R, G, and B components of the host image. The scheme achieves a high level of security due to DRPE and at the same time preserves high imperceptibility and robustness due to SVD properties. Simulated results of the proposed scheme are provided to demonstrate the high robustness, not only against the geometric distortion attacks but also against general image processing attacks.(3) An asymmetric cryptosystem based on two-step phase-shifting interferometry (PSI) and elliptic curve (EC) public-key cryptographic algorithm is proposed, in which one image is encrypted to two interferograms by double random-phase encoding (DRPE) in Fresnel domain and two-step phase-shifting interferometry (PSI), and the session keys such as geometrical parameters and pseudo-random seeds, are asymmetrically encoded and decoded with the aid of EC algorithm. The utilization of EC asymmetric cryptosystem solves the problem of key management and dispatch, which is inevitable in the conventional optical symmetric cryptosystems. Not only computer simulation, but also software design and development are carried out to verify the feasibility of the proposed cryptosystem.(4) An optical identity authentication scheme based on the elliptic curve digital signature algorithm (ECDSA) and phase retrieval algorithm (PRA) is proposed. In this scheme, a user’s certification image and the quick response code of the user identity’s keyed-hash message authentication code (HMAC) with added noise, serving as the amplitude and phase restriction, respectively, are digitally encoded into two phase keys using a PRA in the Fresnel domain. The proposed authentication scheme employs multilevel verification and recognition, including image matching and ECDSA signature verification, assigned to the amplitude and phase of the output image, respectively. Furthermore, the introduction of HMAC enhances the security strength of the authentication scheme. Theoretical analysis and numerical simulations both validate the feasibility of our proposed scheme.