Analysis and design of impulse attack free generalized joint transform correlator optical encryption scheme

We demonstrate in this paper that the generalized joint transform correlator (JTC) optical encryption method shows vulnerability to chosen-plaintext attacks. An unauthorized user, who has access to probe the encryption machine, can obtain the encryption keys with the help of the impulse function as chosen plaintext. The vulnerability of traditional joint transform correlator encryption is also analyzed in this paper. To prevent this attack, an enhanced angular multiplexing double-arm encryption solution is proposed. Cryptanalysis indicates that the improved scheme is robust to the chosen-plaintext attacks. Based on the analysis, a guideline for designing impulse attack free encryption system is discussed. Numerical simulation is also presented to show the validity of the proposed approach.