Supergenpass algorithm in python

sgp.py

__author__ = 'Dan Connolly'
__contact__ = 'http://www.madmode.com/'
__license__ = 'dedicated to the public domain, aka CC0'

from base64 import b64encode
from hashlib import md5
import re

def gp2_generate_passwd(Passwd, Len):
    '''
    >>> gp2_generate_passwd('abc' + ':' + 'google.com', 10)
    'jZDs3ya7xD'
    '''
    i = 0
    while i < 10 or not gp2_check_passwd(Passwd[:Len]):
        Passwd = b64_md5(Passwd)
        i += 1

    return Passwd[:Len]

def gp2_check_passwd(Passwd):
    '''
    fails to start with lowercase:
    >>> gp2_check_passwd('N4itI90rEFaPk1Jvkf3BPgAA'[:10])
    False

    fails to contain a digit:
    >>> gp2_check_passwd('xprtwflIodwvOYgsw8JD3AAA'[:10])
    False
    
    >>> gp2_check_passwd('2JUcGu9hA8NkX0UL77REjgAA'[:10])
    False
    >>> gp2_check_passwd('IvkBoBLDReR1YfZeRCUjqAAA'[:10])
    False
    >>> gp2_check_passwd('5hcPWN9KmrCY0luFho8wYQAA'[:10])
    False

    Finally, check passes:
    >>> gp2_check_passwd('jZDs3ya7xDQKEVZ4DDzSXgAA'[:10])
    True
    '''
    def search(pattern):
        m = re.search(pattern, Passwd)
        return -1 if m is None else m.start(0)
    
    return (search('[a-z]') == 0
            and search('[0-9]') > 0
            and search('[A-Z]') > 0)


def b64_md5(Passwd):
    r'''
    >>> p = 'abc:google.com'
    >>> for i in range(0, 17):
    ...     p = b64_md5(p)
    ...     print i, repr(p)
    0 'JasE6Az8W8UQsq4No2wjCQAA'
    1 '4Jy6chsnepsYtHDjZf9iNQAA'
    2 'qB9yfmG2Arg7EEL38kwV6wAA'
    3 'dTSZtVtmlB9NIomTZSBzZwAA'
    4 'XjP6oN5WsuJ89IfevhpLZQAA'
    5 'o5J7O1J8lkIhGg9xWcerKwAA'
    6 'Wr28EzVsGEHqt14AHpi1PgAA'
    7 'hsQ1IjYeo0GMnCFkOeWB4AAA'
    8 '5P9Kx08wg60RUFzLZItimgAA'
    9 'T8hb4nOhC2w8ZlZzm4b9mAAA'
    10 'N4itI90rEFaPk1Jvkf3BPgAA'
    11 'xprtwflIodwvOYgsw8JD3AAA'
    12 '2JUcGu9hA8NkX0UL77REjgAA'
    13 'OeMSjl48mn0Ook0dwEpjcwAA'
    14 'IvkBoBLDReR1YfZeRCUjqAAA'
    15 '5hcPWN9KmrCY0luFho8wYQAA'
    16 'jZDs3ya7xDQKEVZ4DDzSXgAA'
    '''

    # Using 'A' rather than '=' for padding seems to fall out
    # of the base64 algorithm used. But I don't know why they use 98
    # rather than +/ for the altchars.
    return b64encode(md5(Passwd).digest(), '98').replace('=', 'A')