Optical security system employing shifted phase-encoded joint transform correlation and orthogonal code

Efficient cryptographic techniques are very much crucial in protecting confidential information, including personal identification and biometrics. Reliable encryption algorithm must restrict any and all unauthorized access to information or information system. At the same time, the algorithm should reproduce the information to its authorized users without any loss of distortion. Optics has played an important role in devising fast and reliable security systems without requiring complex architecture. Though several optical security techniques have so far been proposed in the literature, but they are not as successful in providing with robust performance and strong security against unauthorized access. This paper proposes an efficient optical security system utilizing a joint transform correlation (JTC) technique and orthogonal encoding scheme. Multiple information in the form of images are encoded using orthogonal codes and then mixed together. The single encoded image is fed to the JTC scheme, where the input image is nonlinearly encrypted by the key using Fourier lenses. The proposed technique also includes a fringe-adjusted filter to eliminate noisy signals and hence to enhance the decryption performance. Computer simulation investigation verifies that the scheme can secure the confidential information from any threats.