A key refreshing technique to reduce 4-way handshake latency in 802.11i based networks

Authentication per frame is an implicit necessity for security in Wireless LANs (Local Area Networks). 802.11i security framework proposes encryption and MIC based authentication of data frames. In this, the key is not refreshed every time a frame is sent. For refreshing the key entities explicitly perform a 4-way handshake to evaluate PTK. 4-way handshake also ensures that involved entities have the same transient key (refreshed key). 4-way handshake involves computation cost. It also adds to the communication cost in the wireless environment, as data frame are utilized for this purpose. 4-way handshake in the 802.11i framework happens to be prone to DoS attacks (especially due to first message of the 4-way handshake). We propose a novel per frame key refreshing method that do away with the 4-way handshake. It does not require extra bits or extra frame for this purpose and also no change in the existing frame format is required. It uses existing key, frame sequence number along with the authentication stream generator for key refreshing.