Which component of WPA uses a rekeying mechanism to provide fresh encryption and integrity keys?

Which component of WPA uses a rekeying mechanism to provide fresh encryption and integrity keys?

• A. WEP
• B. TKIP
• C. AES-CCMP
• D. PSK

Answer: (B)

The mechanism that provides fresh encryption and integrity keys in WPA is TKIP. TKIP was designed to fix the flaws of WEP by introducing per-packet keying and a rekeying process. It generates a new per-frame key for encryption by mixing a Temporal Key with the IV and the devices’ addresses, and the four-way handshake refreshes the keying material (the Pairwise Transient Key) used to derive these per-packet keys. This means the actual encryption and integrity keys change frequently, so even if one key were compromised, past frames remain protected. WEP uses a static key with no rekeying, PSK is just an authentication key, and AES-CCMP, while also using refreshed keys via the handshake, is a different, stronger encryption method; the rekeying mechanism described in WPA’s context is most directly associated with TKIP.

The mechanism that provides fresh encryption and integrity keys in WPA is TKIP. TKIP was designed to fix the flaws of WEP by introducing per-packet keying and a rekeying process. It generates a new per-frame key for encryption by mixing a Temporal Key with the IV and the devices’ addresses, and the four-way handshake refreshes the keying material (the Pairwise Transient Key) used to derive these per-packet keys. This means the actual encryption and integrity keys change frequently, so even if one key were compromised, past frames remain protected. WEP uses a static key with no rekeying, PSK is just an authentication key, and AES-CCMP, while also using refreshed keys via the handshake, is a different, stronger encryption method; the rekeying mechanism described in WPA’s context is most directly associated with TKIP.