Generate random passwords from dictionary

random-dict-password.py

#!/usr/bin/env python

# random-dict-password.py - Generate random passwords from a dictionary
# Copyright (c) 2012 Haggai Eran
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import random
from math import log

def filter_word(word):
    return not word.endswith("'s\n")

def load_dictionary():
    with file('/usr/share/dict/words') as f:
        return set(line.strip().lower() for line in f.readlines() if filter_word(line))

if __name__ == '__main__':
    dictionary = load_dictionary()
    length = len(dictionary)
    print "Dictionary length: %d. Password entropy: %f" % (length,4*log(length)/log(2))
    words = random.sample(dictionary, 4)
    print ' '.join(words)