weakkey1 is the basic test. Using FMS at a particular byte,
  test whether key is resolved, weak, etc. Used to estimate
  the percentage of resolved cases which are weak.

weakkey2 tests how weak is a random key. We test a random key
  at all byte locations and tabulate how many keys are weak at
  none, one, ... , all five locations.

weakkey3 does a key recovery using FMS


rc4.c is an adapted version of rc4.c by devine
wkeys.c has the FMS code, mostly.

weakkeys?.c are application wrappers which drive the attacks.,
   although weakkeys3 does have the statistical stuff.