In cryptography , RC4 ( also known as ARC4 or ARCFOUR meaning Alleged RC4 , see below ) is one of the most common software stream ciphers . It is used in popular protocols like Secure Sockets Layer ( SSL ) ( to protect Internet traffic ) and WEP ( to secure wireless networks ) . In cryptography , RC4 ( also known as ARC4 or ARCFOUR meaning Alleged RC4 , see below ) 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 ) .