Password Generator

genpass.py

#! /usr/bin/env python
#
# Dependency:
# pip install keyring
#
# Fred C. http://github.com/0x9900/
#
"""
Generate a passworg base on the domain name of a website, your
userid on this website and a key.

The first time you use this program it will as you a key. This key
will be stored in your Mac keychain.

Examples:

]$ ./genpass.py fred www.yahoo.com
yahoo.com: Password: vk61-borA-wlIu-BYSK
]$ ./genpass.py fred yahoo.com
yahoo.com: Password: vk61-borA-wlIu-BYSK
]$ ./genpass.py fred YAHOO.COM
yahoo.com: Password: vk61-borA-wlIu-BYSK

"""
import getpass
import keyring
import os
import random
import sys

from argparse import ArgumentParser
from argparse import RawDescriptionHelpFormatter
from hashlib import sha256
from urlparse import urlparse

PASSWD_LEN = 19
ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz'

def normalize_url(url):
  url = urlparse(url)
  url = url.netloc or url.path
  url = url.lower().replace('www.', '')
  return url

def get_key(program, token='Password Generator'):

  """Try to find the encryption key for that token in the keyring. If
  the key cannot be found prompt the user.

  """
  key = keyring.get_password(program, token)

  # the key hasn't been found in the keyring. Request for a new one.
  if not key:
    key = getpass.getpass('Encryption key: ')
    try:
      keyring.set_password(program, token, key)
    except keyring.errors.PasswordSetError as exp:
      sys.stderr.write(exp + '\n')

  return str(key)

def parse_arguments():
  parser = ArgumentParser(
    description="Password generator",
    epilog=globals()['__doc__'],
    formatter_class=RawDescriptionHelpFormatter
  )
  parser.add_argument('-u', '--username', help="Site username")
  parser.add_argument('-d', '--url', help="Site's domain name http://example.com/")
  parser.add_argument('args', nargs=2)
  opts = parser.parse_args()

  if opts.username is None and opts.args:
    opts.username = opts.args.pop(0)
  if opts.url is None and opts.args:
    opts.url = opts.args.pop(0)
  if not opts.username or not opts.url:
    parser.error()

  opts.url = normalize_url(opts.url)

  return opts

def main():
  opts = parse_arguments()
  program_name = os.path.basename(sys.argv[0])
  key = get_key(program_name)
  seed = sha256(opts.url + key + opts.username).hexdigest()
  random.seed(seed)
  charlist = [c for c in ALPHABET]
  random.shuffle(charlist)
  password = ''.join([c if i%5 else '-' for i, c in
                      enumerate(charlist[:PASSWD_LEN], 1)])
  print "Site: {}: Password: {}".format(opts.url, password)

if __name__ == '__main__':
  main()