Python password generator

genpass.py

#!/usr/bin/env python

import crypt
import random
import string
import sys

PASSWORD_CHARS = string.ascii_uppercase + string.ascii_lowercase + string.digits
MD5_SALT_CHARS = PASSWORD_CHARS + '/'
DES_SALT_CHARS = string.ascii_uppercase + string.ascii_lowercase

def random_string(N, charset=PASSWORD_CHARS):
   # http://stackoverflow.com/questions/2257441/random-string-generation-with-upper-case-letters-and-digits-in-python
   return ''.join(random.choice(charset) for _ in range(N))

if __name__ == '__main__':
  pw_len = 9
  if len(sys.argv) > 1:
     pw_len = int(sys.argv[1])
  password = random_string(pw_len)
  # This only works when the libc crypt function supports it.
  md5 = crypt.crypt(password, '$1$' + random_string(7, MD5_SALT_CHARS) + '$')
  des = crypt.crypt(password, random_string(2, DES_SALT_CHARS))

  print("Password: {0}\nMD5: {1}\nDES: {2}".format(password, md5, des))