Image Encryption and Decryption by Means of an Optical Phase Mask

In this paper, we propose a novel encryption method as an optical architecture of cryptography, based on the grouping of the information in the Fourier plane. This grouping is termed segmentation; it was been used to make the so-called segmented filter used in optical target recognition to optimize the performances of the correlator decision. By using the concept of segmented filter, encryption can be considered as an image encrypting with a segmented phase mask called keys and consists in modifying the phase profile of the original image by multiplying it by the adapted phase mask. In our case, this key will group information gathered from different sub-keys according to a well-defined criterion. The decryption is simply performed by an optical correlation by using a composed correlation filter, since the encryption keys are complex images, they cannot be randomly found in a reasonable time. Excellent decryption image is obtained.