Information, Computer and Network Security Terms Glossary and Dictionary

RC4, or Rivest Cipher 4, is the most widely-used software stream cipher and is used in popular protocols such as Secure Sockets Layer (SSL) (to protect Internet traffic) and WEP (to secure wireless networks). RC4 was designed by Ron Rivest of RSA Security in 1987. RC4 generates a pseudorandom stream of bits (a "keystream") which, for encryption, is combined with the plaintext using XOR as with any Vernam cipher; decryption is performed in the same way. While remarkable in its simplicity, RC4 falls short of the high standards of security set by cryptographers, and some ways of using RC4 lead to very insecure cryptosystems (including WEP). It is not recommended for use in new systems. However, some systems based on RC4 are secure enough for practical use.

Related Terms

RC4: Rivest Cipher 4