John passwd file to mschapv2acc file converter

accgen.rb

#!/usr/bin/ruby
require 'digest/sha1'

if !ARGV[0] || !ARGV[1]
  puts "Usage: accgen.rb <john-style-passfile.txt> <mschapv2acc-bin-output>"
  puts ""
  puts "Takes a John-sytle passwd file as input, separated as follows:"
  puts "username:::AUTH_HASH:RESPONSE_HASH:PEER_HASH"
  puts "The output file is ready for mschapv2acc cracking."
  puts ""
  exit
end

def hex2bin(s)
  s.scan(/../).map { |x| x.hex.chr }.join
end

input = File.read(ARGV[0])
out = File.open(ARGV[1], 'wb')

input = input.split("\n")[0] if input =~ /\n/

input_array = input.split(":")

user = input_array[0]
auth = hex2bin(input_array[3])
resp = hex2bin(input_array[4])
peer = hex2bin(input_array[5])
digest = Digest::SHA1.new
digest.update(peer)
digest.update(auth)
digest.update(user)
challenge = digest.digest[0..7]


out.write user.length.chr + "\x00\x00\x00" + user + auth + peer + challenge + resp

out.close