Optical Cryptography System Based on Joint Transform Correlation

The paper presents a review of optical cryptography techniques using joint transform correlation (JTC) algorithm. The given input image contains confidential information, such as personal identification, photo, which is then encrypted using an encryption key. Optical JTC technique is employed to perform the encryption and decryption processes using optical lenses and other equipments. The input image and the key are introduced to the same input plane which is then Fourier transformed. Joint power spectrum (JPS) of the resultant signal is recorded and inverse Fourier transformed to derive the encrypted signal. At the receiving end, the received encrypted signal is first Fourier transformed and multiplied by the key used in encryption. Inverse Fourier transformation retrieves the original information without any distortion. The JTC techniques are simple and fast, which would offer excellent and efficient cryptography systems for real-time applications.