Ciphertext-Only Attack on Phase-Shifting Interferometery-Based Encryption

The phase-shifting interferometry-based (PSI-based) encryption is one of most typical optical encryption systems. In this paper, we demonstrate a new approach to ciphertext-only attack (COA) on PSI-based encryption, revealing that there is serious security risk in PSI-based encryption. With the proposed COA approach, an opponent can crack the ciphertexts directly without use of the keys of the system. This demonstration, as far as our best knowledge, shows the PSI technique is vulnerable to COA for the first time. A series of attack results are shown to demonstrate the feasibility and robustness of the attack method. Our study reveals a critical security issue that should be taken in to account when designing an optical information security system.