STREAM CIPHER

Abstract

In this paper we discuss about the Stream Cipher. Stream cipher encrypt single bit at a time. This will happen to adding a key stream to a plain text bit. Stream cipher is small and fast, therefore its use in small embedded system. There are main two stream cipher:- A5/1 cipher for GSM mobile. Over the air for the GSM encryption is also needed to protect the conversation. Approximately the design of A5 is leaked in 1994. A5/1 was developed in 1987 and A5/2 was developed in 1989. This both were kept secret.It leaked in 1994 and reverse engineered in 1999 by Marc Briceno. RC4 is widely used stream ciher for its simplicity, speed and efficiency. RC4 is used for secure the Internet traffic. RC4 was designed in 1987 by Ron Rivest. RC4 was at first secret, however an outline of it absolutely was announce to the Cypherpunks mails in 1994. There are many attacks happens on both stream cipher, we discuss two of them in this paper.