Vulnerability to chosen-plaintext attack of optoelectronic information encryption with phase-shifting interferometry

摘要

The optical cryptosystem based on phase-shifting interferometry (PSI) is one of the most interesting optical cryptographic schemes in recent years. However, we find that the PSI technique provides an attractive method to record the ciphertext, but contributes little to the security level of the cryptosystem. From the cryptanalysis point of view, in a certain simplified case, an attacker is only required to crack two equivalent decryption keys instead of the original random phase keys and geometric key. Moreover, a chosen-plaintext attack method is proposed, in which an impulse function is chosen as a known plaintext. By using this attack, the attacker can effectively recover any plaintext from the corresponding ciphertext. The validity of the attack is verified by computer simulations.