mkpass.py

#!/usr/bin/env python
typable_chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789`-=[]\\;',./~!@#$%^&*()_+{}|:\"<>?"
import sys, hmac, hashlib, base64, getpass
from Crypto.Random import random
def mkpass(len):
    passwd = ""
    for i in range(len):
        passwd += random.choice(typable_chars)
    return passwd

def inject(passwd, raw_inject_index, reserved, seed, pwlen, start_char, chars):
    offset = seed % pwlen

    for raw_look_index in range(pwlen - reserved):
        look_index = (raw_look_index + seed + reserved) % pwlen

        if start_char <= ord(passwd[look_index]) < start_char + chars:
            return passwd

    inject_index = (raw_inject_index + seed) % pwlen

    orig = ord(passwd[inject_index])
    replacement = start_char + (orig + seed) % chars

    list_passwd = list(passwd)
    list_passwd[inject_index] = chr(replacement)

    return "".join(list_passwd)

def restrict(passwd, seed, start_char, chars, filter=None):
    list_passwd = list(passwd)

    for index in range(len(passwd)):
        orig = ord(passwd[index])
        if filter is not None:
            if filter(orig):
                continue
        elif start_char <= orig < start_char + chars:
            continue

        replacement = (seed + index) % chars + start_char
        list_passwd[index] = chr(replacement)

    return "".join(list_passwd)

def hashpass(key, tag, pwlen=8, options="dpc"):
    base = base64.b64encode(hmac.new(key, tag, hashlib.sha1).digest())
    #print "Raw: " + base
    passwd = base

    if options:
        seed = sum(map(ord, base.rstrip("=")))

        if "D" in options:
            passwd = restrict(passwd, seed, 48, 10)
        if "P" in options:
            isalnum = lambda c: chr(c).isalnum()
            passwd = restrict(passwd, seed, 65, 26, isalnum)

        if "d" in options:
            passwd = inject(passwd, 0, 4, seed, pwlen, 48, 10)
        if "p" in options:
            passwd = inject(passwd, 1, 4, seed, pwlen, 33, 15)
        if "c" in options:
            passwd = inject(passwd, 2, 4, seed, pwlen, 65, 26)
            passwd = inject(passwd, 3, 4, seed, pwlen, 97, 26)

    return passwd[:pwlen]

if __name__ == "__main__":
    if len(sys.argv) < 2:
        print "Your password is: " + mkpass(8)
    elif sys.argv[1] == "-h":
        key = getpass.getpass("Master key: ")
        tag = raw_input("Tag: ")
        while tag:
            options = "dpc"
            pwlen = 8
            if "!" in tag:
                tag, options = tag.split("!")
                if "," in options:
                    options, pwlen = options.split(",")
                    pwlen = int(pwlen)

            passwd = hashpass(key, tag, pwlen, options)
            print "Your password is: " + passwd

            tag = raw_input("Tag: ")
    else:
        print "Huh?"