Asymmetric multiple-image encryption system based on a chirp z-transform

An asymmetric multi-image encryption system based on the chirp z-transform (CZT) is demonstrated. The setup is a hybrid architecture that combines a double-random-phase encryption scheme in 4f configuration and a multiplexing procedure based on the CZT. The setup allows encodement of multiple images and their transmittal in a single multiplexed element. The decryption stage has a compact design that allows retrieval of several data without cross-talk noise. Since the system is asymmetric, the users' decryption keys are different from those used in the encryption process, resulting in an encoding scheme resistant to cryptanalysis attacks. It is demonstrated that multiplexing based on the CZT allows functionality expansion of the static encoding setups (optical, digital or hybrid) to a dynamic range, a fact that provides a versatile solution to handle large volumes of encrypted data efficiently and safely. The viability of this proposal is verified using virtual optical systems.