Mixing means that information in one part of the system communicates during the operation of the system with other parts of the system. This easily established property is sufficient to cause random information inserted during the encryption phase of the invention to diffuse across the plaintext. The cryptography system of Guan is slightly relevant to the present invention. In Guan's system a type of cellular automaton is carefully constructed so that another cellular automaton which is the original cellular automaton's inverse can be found by solving a complicated system of polynomial equations. Encryption is performed by applying the cellular automaton once to the message.
Decryption is performed by applying the inverse cellular automaton once to the ciphered message.
The security of the system depends on difficulty of solving for the inverse cellular automaton. The differences between Guan's scheme and the present invention are many and major. As this is the closest known prior art to the present invention, it is worthwhile to consider these differences in detail. First, the object of Guan is a public-key cryptosystem. This invention is a private-key cryptosystem.