Quick & dirty script for decrypting HP Bios passwords created by HpqPswd.exe

HpqPswdDecryptor.py

import argparse, struct
from Crypto.Cipher import AES

if __name__ == '__main__':
  parser = argparse.ArgumentParser(description='HpqPswd Decryptor')
  parser.add_argument('-f', '--file', required=True, help='Input file')
  parser.add_argument('-k', '--key', default='4a14........................................................1e33')
  args = parser.parse_args()

  f = open(args.file, 'rb')
  if f.read(8) != '_HPPW12_':
    raise Exception('Wrong magic')

  cipher = AES.new(args.key.decode('hex'), AES.MODE_CBC, '\0'*AES.block_size)
  length, = struct.unpack('<H', f.read(2))
  print cipher.decrypt(f.read(length))

For some reason, I am getting "TypeError: Non-hexadecimal digit found" when I try to decrypt the file.
Has the format of the file changed?

Please make sure you are passing correct key as an argument.

Hi Tobias, I have an old HP Omnibook 300 that is password-locked. When I press Shift-F10 I get a scrambled version of the password. However HP can't descramble it due to this being an old laptop from 1993. Do you know how I could go about descrambling the password on this old machine? Thanks!

@accelerate-science , this script is for decrypting files that start with magic string HPPW12. Similar to the process in this writeup: https://www.serializing.me/2016/10/15/hpqpswd-encrypted-passwords-decryption/. I don't think it will apply to your situation.