Security mechanisms for IEEE 802.11 are defined in this amendment, which includes a definition of WEP for backward compatibility with the original standard, IEEE Std 802.11, 1999 Edition. This amendment defines TKIP and CCMP, which provide more robust data protection mechanisms than WEP affords. It introduces the concept of a security association into IEEE 802.11 and defines security association management protocols called the 4-Way Handshake and the Group Key Handshake. Also, it specifies how IEEE 802.1X may be utilized by IEEE 802.11 LANs to effect authentication.