coWPAtty - Brute-force dictionary attack against WPA-PSK.

Copyright(c) 2004, Joshua Wright <jwright@hasborg.com>

FAQ

Please send questions to the author, and I'll do my best to update this file
to answer common questions.

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Q: Why is it taking so long to test password entries for the correct WPA-PSK
   key?
A: The design of the WPA-PSK algorithms is such that it is difficult to mount
   an effective dictionary attack.  When mounting a dictionary attack, the
   passphrase we are testing has to be hashed with 4096 iterations of the 
   HMAC-SHA1 algorithm (which is really 8192 full SHA1 invocations).  This
   takes a long time, and has to be repeated for each word in the dictionary
   file.

Q: What kind of performance can I expect with coWPAtty?
A: I've done my best to optimize the code to squeeze out as much performance as
   possible.  The OpenSSL SHA1 code is faster then the C and i386-assembler
   implementations that are included with the tool, and the default option in
   the Makefile.  Here are the results from the two systems I use for
   development and testing:

   Processor: Intel Pentium 3 450Mhz, 897.84 bogomips, 9.8 passphrases/second
   Processor: Intel Pentium 4 3.8GHz, 5570.56 bogomips, 69.3 passphrases/second

Q: How can I accelerate the dictionary cracking process?
A: Make sure you are using the OpenSSL libraries on your system (openssl.org).
   If you are running an OpenSSL package that came with your Linux vendor, try
   downloading and compile your own local version, using optimizations for your
   processor.  Don't expect this to result in a major performance increase
   though.
   The best thing to do is run coWPAtty on the system with the fastest
   processor you have access to.  If you have success running coWPAtty on
   systems other than Intel 32-bit systems, please drop me a line.
   Alternatively, you can distribute the cracking load across multiple systems.
   Simply split the dictionary file into multiple pieces, and distribute the
   pieces to each system you want to use in the cracking process, along with a
   copy of the code and the capture file.

Q: My passphrase isn't reported by coWPAtty, even though I know it's in the
   dictionary file. What gives?
A: Make sure you have supplied the correct SSID on the command-line.  An
   incorrect SSID will cause coWPAtty to be unable to identify the correct
   passphrase.  Also make sure the dictionary is a unix text file not 
   DOS.  DOS text files have a control character at the end of each line 
   that will be used as part of the passphrase and screw up the 
   resulting hashes.

Q: Is the SSID case-sensitive?
A: Yes.  Be certain you have the correct case for the SSID.

Q: Why don't you add code to automatically cull the SSID from beacon frames?
A: If the SSID is cloaked in beacon frames, you need to extract it from the
   association request information from the client station.  I could add this
   parser, but it's easier to get it from a tool like Kismet.

Q: What is the pertinent information for the sample capture file?
A: Use the following information for the sample WPA four-way handshake in the
   eap-test.dump file:

   SSID: "somethingclever"
   Passphrase: "family movie night"

Q: Does your choice of the name coWPAtty reflect your feelings about the IEEE
   802.11i specification?
A: No, not at all.  In fact, the coWPAtty name was selected to reflect the
   quality of this tool.  The IEEE 802.11i committee did a good job designing
   TKIP with the problems with paucity of processing capacity and desire to
   be applied with a software upgrade to existing hardware.  The use of the
   pbkdf2 algorithm to hash the PSK was a good call - it makes dictionary
   attacks such as this one much less effective.

Q: Why does the same code work for WPA1-PSK and WPA2-PSK?
A: The PBKDF2 function is common between both systems.

Q: What's up with Ken Jennings?
A: That's what I'd like to know too!  Maybe he can take a look at this code for
   me when he's not busy kicking everyone's ass on Jeopardy.