Analytic known-plaintext attack on a phase-shifting interferometry-based cryptosystem.

We demonstrate a new analytic approach to a known-plaintext attack (KPA) on an optical cryptosystem based on the phase-shifting interferometry (PSI) technique. With the proposed analytic attack method, an opponent can access the exact decryption keys and obtain perfect attack results. This demonstration, to the best of our knowledge, shows for the first time that the optical cryptosystem based on the PSI technique is vulnerable to KPA.