Optical cryptosystem model based on the keyspace transformation

Abstract The existing optical encryption schemes always use the same cryptosystem for both encryption and decryption processes. This fact makes the cryptosystem vulnerable to some specific attacks. A new model of optical cryptosystem based on keyspace transformation is proposed to avoid this security risk. The designed cryptosystem following the principles of this model can be very safe. The senders and receivers use different keys for encryption and decryption processes, respectively. This proposed model includes an encryption subsystem, a decryption subsystem, and a keyspace transformation method. Some specific schemes following the principles of the proposed model are given as instances for studying the proposed model. The validity, generality, collision-resistant property, and robustness of the proposed model are discussed. The proposed model provides a new way of designing optical cryptosystems.