TKIP has three main elements to enhance encryption:
A per-packet key mixing function
An improved Message Integrity Code (MIC) function named Michael
An enhanced IV including sequencing rules
Basically, TKIP is an interim fix for WEP, deployed as a simple software/firmware upgrade. A number of design compromises are made in order to maintain backwards compatibility with the large base of existing and deployed hardware in the field. TKIP, however, fixes all of the known vulnerabilities associated with WEP, at the time of this writing.
The client starts off with two keys: a 128-bit encryption key and a 64-bit data integrity key obtained securely during the 802.1x negotiation. The encryption key is called the Temporal Key (TK). ...