#!/usr/bin/python

# Copyright 2009:  dogbert <dogber1@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#
# This script generates master passwords which can be used to unlock
# the BIOS passwords of most Fujitsu Siemens laptops (Lifebook, Amilo etc.).
# You have to install python for running this script.

import os

# d'oh
def generateCRC16Table():
	table = []
	for i in range(0, 256):
		crc = (i << 8)
		for j in range(0, 8):
			if crc & 0x8000:
				crc = (crc << 1) ^ 0x1021
			else:
				crc = (crc << 1)
		table.append(crc & 0xFFFF)
	return table

# D'OH
def calculateHash(word, table):
	hash = 0
	for c in word:
		d = table[(ord(c) ^ (hash >> 8)) % 256]
		hash = ((hash << 8) ^ d) & 0xFFFF
	return hash

def hashToString(hash):
	return (chr(ord('0') + ((hash>>12) % 16) % 10) + chr(ord('0') + ((hash>>8) % 16) % 10) + chr(ord('0') + ((hash>>4) % 16) % 10)  + chr(ord('0') + ((hash>>0) % 16) % 10)) 
 
def decryptCode(code, table):
	return hashToString(calculateHash(code[0:4], table)) + hashToString(calculateHash(code[4:8], table))

print("Master Password Generator for FSI laptops (hexadecimal digits version)")
print("Copyright (C) 2009 dogbert <dogber1@gmail.com>")
print("")
print("After entering the wrong password for the third time, you will receive a")
print("hexadecimal code from which the master password can be calculated,")
print("e.g. 0A1B2D3E or AAAA-BBBB-CCCC-DEAD-BEEF")
print("")
print("Please enter the code: ")
input = raw_input().replace('-', '')
if len(input) == 20: input = input[12:20]
table = generateCRC16Table()
password = decryptCode(input.upper(), table)
print("")
print("The master password is: " + password)
if (os.name == 'nt'):
	print("Press a key to exit...")
	raw_input()