Passphrase generator based on the Diceware method by A. G. Reinhold.

diceware.py

import random
import sys
try:
    from urllib.request import urlopen
except ImportError:
    from urllib import urlopen


DICEWARE_WORDLIST_URL = 'http://world.std.com/~reinhold/diceware.wordlist.asc'
BEALE_WORDLIST_URL = 'http://world.std.com/~reinhold/beale.wordlist.asc'


class DicewareGenerator(object):
    """
    Passphrase generator based on the Diceware method by A. G. Reinhold.

    More about Diceware: http://world.std.com/~reinhold/diceware.html

    YOU PROBABLY SHOULDN'T USE THIS. BUT IF YOU REALLY WANT TO, THEN YOU SHOULD
    READ THIS FIRST: http://world.std.com/~reinhold/dicewarefaq.html#electronic

    """
    def __init__(self, url=DICEWARE_WORDLIST_URL):
        self.load_diceware_file(url)
        self.random = random.SystemRandom()

    def load_diceware_file(self, url):
        wordlist = {}
        for line in urlopen(url):
            try:
                number, word = line.decode('utf-8').rstrip('\n').split('\t')
            except ValueError:
                pass
            else:
                wordlist[number] = word
        self.wordlist = wordlist

    def get_word(self, number=None):
        if number is None:
            number = ''.join(self.random.choice('123456') for i in range(5))
        return self.wordlist[number]

    def generate_passphrase(self, num_words=5, sep=' '):
        return sep.join([self.get_word() for i in range(num_words)])


if __name__ == '__main__':
    kwargs = {}
    if len(sys.argv) > 1:
        kwargs['url'] = sys.argv[1]
    diceware = DicewareGenerator(**kwargs)

    kwargs = {}
    if len(sys.argv) > 2:
        kwargs['num_words'] = int(sys.argv[2])
    sys.stdout.write('%s\n' % diceware.generate_passphrase(**kwargs))