Encryption of Optically Compressed Medical Images Using Phase Matrix

Nowadays computer network is a blessing to modern society due to its various features which are especially suitable for cloud computing, teleconferencing etc. A lot of information transmission is the basic criteria of these applications. Unfortunately, cyber attackers are active everywhere and they try to misuse this facility. Therefore, this information should be transmitted securely. Moreover, this information should be compressed for proper optimization of bandwidth of the transmitted medium. In this communication, we propose a novel method for compression and encryption of medical images using optical process which is suitable for secure teleconferencing. For our research work, we have used sinusoidal amplitude grating. Medical images are modulated with the help of high frequency grating frequency and variable orientation angle. As a result of modulation, three spectrums have been generated for each image. One spectrum is the FT of the image (center spectrum) and other two are sidebands. Out of these two sidebands, only one sideband of each image is taken for filtering as the sidebands of the image are symmetrical to each other. Inverse Fourier Transform is applied at specific zones to filter the output images. As only one sideband is used for image recovering, therefore this method is effective for teleconferencing in rural medical system using optimum bandwidth. We have used chosen ciphertext attack to prove the effectiveness of our method and we have proved that our system is secure.