Optical encryption system employing orthogonal code and multiple reference-based joint transform correlation

Abstract

The paper proposes a new technology to ensure enhanced security of personal identification information or binary images through the use of encryption and multiplexing processes. Orthogonal codes are employed to encrypt the given input images so that multiple encoded images can then be mixed together to save storage space or transmission bandwidth. The multiplexed and encoded image is further encrypted employing multiple reference-based joint transform correlation. The address code is fed into four channels after performing phase shifting on them by different amount. The input image is introduced to the channels to obtain joint power spectra (JPS) signals through Fourier transformation. The resultant signals are phase-shifted and then combined to form a modified JPS signal which is then inverse Fourier transformed to yield the final and highly secure encrypted image. At the receiver, the image is Fourier transformed and multiplied by the address code used in encryption. Inverse Fourier transformation yields the multiplexed and encoded image which is then decoded using orthogonal codes. The proposed technique enhances the security performance by implementing orthogonal coding and nonlinear encryption algorithms so that no unauthorized access to or interception of information is possible. Performance of the technique is evaluated through computer simulation.