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Protocols > SSL/TLS - Pg. 143

General Cryptographic Concepts CHAPTER 10 143 WEP WEP is particularly worth knowing about, if for no other reason than it is an object lesson in the old maxim "don't write your own cryptography unless you are a cryptography expert," along with its corollary, "you are not a cryptography expert." TKIP While WEP was being broken by attackers, the WiFi Alliance approved a subse- quent protocol, TKIP --the Temporal Key Integrity Protocol. TKIP was approved as a part of the Wi-Fi Protected Access (WPA) protocol. TKIP uses RC4 as well, but has several advantages over WEP--most notably, each data packet is encrypted using a different key, and instead of merely concatenat- ing the IV and the key, TKIP combines them using a key mixing function. TKIP also uses a sequence counter, so that replay attacks fail, as the sequence counter is different when the replay attack is attempted. The final result of the WEP debacle was the adoption of WPA and the follow- up, WPA2.