#!/usr/bin/python
# Accepts a passphrase on the command line and converts it to a WEP key.
# The algorithm extends the passphrase to 64 characters and runs it
# through md5sum.  The result is the WEP key.
# 
# Resources for this most simple of algorithms are difficult to find on the
# Internet because so many people want to sell a program to do it. 

import md5
import sys

def usage():
    print "usage: %s PHRASE" % sys.argv[0]
    print "  Enclose PHRASE in quotes if it includes whitespace or shell meta-chars."
    print "  PHRASE was '%s'" % phrase
    sys.exit(1)

if len(sys.argv) < 2 or not sys.argv[1]:
  usage()

def makekey(phrase,size=104):
    if len(phrase) > 64:
	phrase = phrase[:64]

    m = md5.new()
    c = 64

    while c >= len(phrase):
      m.update(phrase)
      c -= len(phrase)

    if c:
      m.update(phrase[:c])

    return m.hexdigest()[:size/4]

phrase = sys.argv[1]
size = 40
print '     passphrase: "%s"' % phrase
print "%d bit WEP key: %s\n" % (size,makekey(phrase,size))