A symmetric stream encryption algorithm that is used to protect data in several versions of the SSL and TLS protocols, as well as in the WEP and WPA wireless security standards. RC4 was created by Ronald Rivest, and is owned by RSA Security LLC. The algorithm is noted for its high speed of operation and ease of implementation at both the software and hardware levels. The cipher allows the use of variable-length keys, which means the level of data protection can be adjusted. In its present form the algorithm is vulnerable to a range of attacks, for which reason in 2015 it was banned from use in the TLS protocol.