WEP, or Wired Equivalent Privacy, is the default protocol used for securing wireless LANs. It uses the RC4 stream to encrypt data which is transmitted over the air, using usually a single secret key - the WEP key - of a length of 40 or 104 bit.

aircrack-ptw is a WEP key cracking tool that utilizes a special method to break 104-bit WEP in less than 60 seconds. Using aircrack-ptw, it is possible to recover a 104 bit WEP key with probability 50% using just 40,000 captured packets. For 60,000 available data packets, the success probability is about 80% and for 85,000 data packets about 95%.

Using active techniques like deauth and ARP re-injection, 40,000 packets can be captured in less than one minute. The actual computation takes about 3 seconds and 3 MB main memory on standard computers. The same attack can be used for 40 bit keys too with an even higher success probability.

Download aircrack-ptw here.