Stream enciphering method, deciphering method and cryptographic communication system

摘要

On a transmitter side, an enciphering means (17) enciphers a plaintext code according to stream enciphering method having a feature in selecting the cycle of a PN signal and then a transmitting means (19) transmits the cryptographic code. On the other hand, on a receiver side, a deciphering means (27) restores the cryptographic code enciphered in the above described procedure to an original plaintext code by carrying out exclusive-OR operations again.