Dynamic multiple-image encryption based on chirp z-transform

A dynamic encryption scheme is demonstrated based on chirp z-transform (CZT). The novel design of this setup allows us to protect multiple images in a multiplexed format and fully recover them without the influence of crosstalk and sample noise. The encoding stage is implemented using the 2D CZT and a Fourier lens. The CZT works with proper frequency parameters to control the position and size of the input frequency spectrum. The accurate positioning leads to an efficient packing of the multiplexed images and a remarkable improvement of the signal-to-noise ratio of the decrypted pictures. The introduction of the CZT in the field of encryption is significant, since it can expand the functionality to a dynamic regime of optical and digital architectures for static encoding. We validated the feasibility of our proposal with the encryption and decryption of a color image sequence and a set of binary images. (paper)