We can precalculate the PMK for a given SSID and wordlist using the genpmk tool with the following command:

genpmk –f <chosen wordlist>–d PMK-Wireless-Lab –s "Wireless Lab

This creates the PMK-Wireless-Lab file containing the pregenerated PMK:

We now create a WPA-PSK network with the passphrase abcdefgh (present in the dictionary we used) and capture a WPA-handshake for that network. We now use Cowpatty to crack the WPA passphrase, as shown in the following screenshot:

It takes approximately 7.18 seconds for Cowpatty to crack the key, using the precalculated PMKs.

We now use aircrack-ng with the same dictionary file, and the cracking process takes over 22 minutes. This shows how much we are gaining because of the precalculation.

In order to use these PMKs with aircrack-ng, we need to use a tool called airolib-ng. We will give it the options airolib-ng, PMK-Aircrack --import,and cowpatty PMK-Wireless...