make_passwd.py

# encoding: utf-8

# References:
# http://serverfault.com/questions/330069/how-to-create-an-sha-512-hashed-password-for-shadow
# http://docs.python.org/dev/library/crypt.html#module-crypt
import crypt
import sys
import argparse
import string
import random

# Tuple == (Hash Method, Salt Length, Magic String, Hashed Password Length)
supported_hashes=[('crypt',2,'',13), ('md5',8,'$1$',22), ('sha256',16,'$5$',43), ('sha512',16,'$6$',86)]

# Extra valid hash functions for checking user input
m_hashing_methods = [z[0] for z in supported_hashes]

def main():
  parser = argparse.ArgumentParser(description='Generate an encrypted password.')
  parser.add_argument('--hash', default='sha512', choices=m_hashing_methods, help='Which Hash function to use')
  parser.add_argument('-s', '--salt', help='Salt to use with Password')
  parser.add_argument('-d', '--debug', action='store_true', help='Output some useful Debug Information')
  parser.add_argument('password')
  args = parser.parse_args()

  # Find the tuple with correct values for hashing function
  l_crypt_tuple = [x for x in supported_hashes if x[0] == args.hash]

  salt_length = l_crypt_tuple[0][1]
  hash_type = l_crypt_tuple[0][2]
  expected_password_length = l_crypt_tuple[0][3]

  if not args.salt:
    salt_word = ''.join((random.choice(string.letters + string.digits + string.punctuation.replace("$","").replace("'",""))) for x in range(salt_length))
  else:
      salt_word = args.salt

  l_result = crypt.crypt(args.password, "".join((hash_type, salt_word)))

  if args.debug:
      print "Salt Used: ", salt_word

  if salt_length > len(salt_word):
      print "Your Salt is shorter than the required one of", salt_length, "characters."

  if args.debug:
      password_length = len(l_result) - salt_length - len(hash_type) - 1
      print "Salt Length: ", len(salt_word), "should be", salt_length
      print "Password Hash: ", password_length

  print l_result

if __name__ == "__main__":
   main()