Public-key-based optical image cryptosystem based on data embedding techniques

Abstract

We propose a public-key-based optical image cryptosystem for practical secure communications since conventional optical crypto- systems that use a symmetric algorithm are confronted by the problem of key delivery. The proposed system employs a hybrid architecture in which a double-random-phase encoding is used to cipher and decipher an image and an asymmetric algorithm is used for ciphering and deci- phering the session key. To solve this problem of key delivery, the double-random-phase encoding algorithm is analyzed to establish a co- vert channel and therefore elucidate the phenomenon that the amplitude part of the ciphered image is less sensitive to quantization error than the other parts in the Fourier and output planes. The session key is then hidden in the covert channel setup in the ciphered image and extracted at the receiver side. Experimental results demonstrate that the amplitude parts in the Fourier and output planes are better suited to convey the session key because they enable reconstructed images with a higher visual quality to be obtained. © 2003 Society of Photo-Optical Instrumentation En- gineers. (DOI: 10.1117/1.1588660)