One method of symmetric key cryptosystems. Encrypts bulk data using a pseudorandom number generator which generates a random data stream. Since stream ciphers have the advantage of being able to implement the algorithm on a smaller scale compared to block ciphers, i.e. data can be encrypted by the bit, etc., it is adopted in radio-communication ciphers, such as in cellular phones and Bluetooth. Stream ciphers are also superior to block ciphers in terms of efficiency of encryption/decryption processing, and are therefore expected to be used widely in an advanced information networked society.
