philpennock/makepassword.py

## makepassword.py
#!/usr/bin/env python3

"""
makepassword: make a decentish password

The -D/--dice option makes a diceware passphrase wordlist; the -B/--bitcoin
option makes a random passphrase wordlist using the Bitcoin BIP39 dictionaries.
The --skey option uses the RFC1751 word-list (but not that algorithm).
Without any of these options, a more traditional password is generated.

The password will start and end with some alphabetic characters, to make it
easier to copy/paste.  In the middle will be a broader selection of characters.
With --open, the distribution is very random, with a strong bias towards
alphabetic characters.
Otherwise, there will be N digits and M punctuation characters.
The digits and punctuation can be specified as a ratio (0, 1) or an absolute
count; for a ratio, the count will be the ceiling of this ratio times the length
of the password.

If -e/--entropy is used then the specified "amount of entropy" will be used and
the length will be ignored.  Eg, a diceware-style password of 96+ bits entropy
can be obtained with:

  makepassword -De 96

Note that for a given amount of entropy, a "conforming" password is longer than
an "open" password because the constraints on counts limit the actual entropy
provided per character.  Note that our entropy calculation is too crude and is
log2(possible_values), not accounting for weighting bias.
"""

__author__ = 'phil@pennock-tech.com (Phil Pennock)'

import argparse
import math
import pathlib
from random import shuffle as random_shuffle  # avoid temptation of random. in namespace
import secrets
import sys
import typing


class WordList(typing.NamedTuple):
    """A diceware-style wordlist with N dice-rolls per word."""
    file: str
    rolls: int = 5


_DEFAULT_LENGTH = 20
_MIN_LENGTH = 8
_DEF_DIGITS_FRAC = 0.2
_DEF_PUNCTUATION_FRAC = 0.25
_DEF_BUFFER_ALPHA = 2
_MIN_ENTROPY = 64

_DEF_WORDLISTS_DIR = pathlib.Path('~/notes/WordLists').expanduser()
_DEF_BITCOIN_DIR = pathlib.Path('~/notes/WordLists/bitcoin').expanduser()
_DEF_WORDLIST = 'eff-large'
_DEF_BITCOIN = 'english.txt'
_BITCOIN_BIP39_WORDCOUNT = 2048  # defined by spec

# TODO: figure out if I want a config file to contain mappings in the dir, and
# source from there, and have a means to indicate the default.
KNOWN_WORDLISTS: typing.Mapping[str, WordList] = {
    'beale': WordList('beale.wordlist.asc'),
    'jp-romaji': WordList('diceware_jp_romaji.txt'),
    'diceware-latin': WordList('diceware_latin.txt.asc'),
    'diceware': WordList('diceware.wordlist.asc'),
    'eff-large': WordList('eff_large_wordlist.txt'),
    'eff-short1': WordList('eff_short_wordlist_1.txt', 4),
    'eff-short2': WordList('eff_short_wordlist_2_0.txt', 4),
}
_CACHED_WORDLISTS: typing.MutableMapping[str, typing.List[str]] = {}
_CACHED_BITCOIN_WORDLISTS: typing.MutableMapping[str, typing.List[str]] = {}


class ExitError(Exception):
    """Exception causing clean process exit without stack-trace."""
    pass


class CountOrRatio(object):
    """Used for options parsing for digit and punctuation amounts.

    If we ask for a password of length 60 and don't otherwise specify the
    number of digits, then the count should scale up from a default suitable
    for length 20 instead of becoming an ever smaller slice of the total.
    """

    def __init__(self, param: typing.Union[float, str], *, base: int = 0):
        self.count = 0
        self.fraction = 0.0
        self.base = 0

        if isinstance(param, str):
            param = float(param)
        if param < 0.0 or base < 0:
            raise ValueError('all parameters must be non-negative')
        if param.is_integer() and param >= 0:
            self.count = int(param)
        elif 0.0 < param and param < 1.0:
            self.fraction = param
        else:
            raise ValueError('bad parameter for a CountOrRatio')
        self.base = base

    def __int__(self) -> int:
        if self.count:
            return self.count
        if self.fraction and self.base:
            return math.ceil(self.fraction * self.base)
        return 0

    def __lt__(self, other: int) -> bool:
        return int(self) < other

    def __add__(self, other: int) -> int:
        return int(self) + other

    def __radd__(self, other: int) -> int:
        return other + int(self)

    def __index__(self) -> int:
        return int(self)

    def __str__(self) -> str:
        if self.count:
            return str(self.count)
        if self.fraction and self.base:
            return f'({self.fraction}·{self.base})={int(self)}'
        return 'err'


def chars_in_range(start: str, end: str) -> typing.List[str]:
    """All ASCII characters in range between start and end inclusive."""
    return [chr(x) for x in range(ord(start), ord(end) + 1)]


class EntropyList(object):
    def __init__(self, entropy_per_char: float, items: typing.List[str]):
        self.entropy = entropy_per_char
        self.items = items

    def __len__(self) -> int:
        return len(self.items)

    def __getitem__(self, key) -> str:
        return self.items[key]


def make_full_dictionary() -> EntropyList:
    """Should return a list 256 entries long."""
    encoded = [chr(x) for x in range(0x21, 0x7F)]
    for _ in range(2):
        encoded.extend(chars_in_range('A', 'Z'))
    for _ in range(4):
        encoded.extend(chars_in_range('a', 'z'))
    encoded.extend(['2', '3', '4', '5', '6', '8'])
    random_shuffle(encoded)  # gratuitous
    # 1 of the values in the range [0x21..0x7E] ... 95 values, log2(95) = 6.56986
    e_per_char = 6.569855608330948
    return EntropyList(e_per_char, encoded)


def make_x_dictionary(x: typing.List[str]) -> EntropyList:
    """Make a list 256 entries long from an input list."""
    # This will have a bias in the results, since are unlikely to have an input which exactly divides 256.
    encoded: typing.List[str] = []
    while len(encoded) < 256:
        encoded.extend(x)
    # This shuffle means the nature of the bias is unpredictable, so matters less.
    # This safety depends upon this dictionary not being persisted to be used across creating multiple passwords,
    # as otherwise the bias will exist and be correlatable across them.
    random_shuffle(encoded)
    return EntropyList(math.log2(len(x)), encoded[:256])


def make_alpha_dictionary() -> EntropyList:
    """Some dictionary of alphabetic chars with unpredictable bias."""
    xs = []
    xs.extend(chars_in_range('A', 'Z'))
    xs.extend(chars_in_range('a', 'z'))
    return make_x_dictionary(xs)


def make_digit_dictionary() -> EntropyList:
    """Some dictionary of digits with unpredictable bias."""
    return make_x_dictionary(chars_in_range('0', '9'))


def secret_bytes_list(length: int, options: argparse.Namespace):
    if options.fixed_nonrandom_hex is not None:
        print('WARNING: using fixed "random" number supplied on command-line, this is INSECURE', file=sys.stderr)
        return list(bytes.fromhex(options.fixed_nonrandom_hex)[:length])  # ignores whitespace
    else:
        return list(secrets.token_bytes(length))


class Random_IntBelow_Generator:
    """Implement an iterator of random numbers in a range [0,max_at_init).

    If the program was invoked with --fixed-nonrandom-hex then the random numbers won't be random.
    This is for testing.  Otherwise, the numbers should be high quality randomness.
    """
    def __init__(self, max_value: int, options: argparse.Namespace):
        self.above_max_value = max_value
        self.static = None
        if options.fixed_nonrandom_hex is None:
            return
        print('WARNING: using fixed "random" number supplied on command-line, this is INSECURE', file=sys.stderr)
        # FIXME: we are just using a whole number of bytes per word here, instead of some number of bits.
        # We should know how many bits are needed and work through them, as per RFC1751 (which is horrid C I don't feel like decoding right now).
        # This will do for now.  But it means that the whole reason I added --fixed-nonrandom-hex is voided, since I can't double-check against the RFC.
        self.static = bytes.fromhex(options.fixed_nonrandom_hex)
        self.static_offset = 0
        self.static_step = 1
        t = max_value
        while t > 256:
            t //= 256
            self.static_step += 1

    def next(self) -> int:
        if self.static is None:
            return secrets.randbelow(self.above_max_value)
        if self.static_offset + self.static_step > len(self.static):
            raise ExitError('exceeded entropy from static source')
        raw_bytes = self.static[self.static_offset:self.static_offset + self.static_step]
        self.static_offset += self.static_step
        v = int.from_bytes(raw_bytes, byteorder='big')
        return v % self.above_max_value


def password_fairly_open(min_entropy: int, length: int, buffer: int, options: argparse.Namespace) -> str:
    """A full password with no minimum constraints except padding alphas."""
    full_characters = make_full_dictionary()
    alpha_characters = make_alpha_dictionary()

    if min_entropy > 0:
        have_entropy = 2 * buffer * alpha_characters.entropy
        length = max(1, math.ceil((min_entropy - have_entropy) / full_characters.entropy)) + 2 * buffer

    raw_binary_offsets = secret_bytes_list(length, options)
    password_chars = []
    password_chars.extend([alpha_characters[n] for n in raw_binary_offsets[:buffer]])
    password_chars.extend([full_characters[n] for n in raw_binary_offsets[buffer:-buffer]])
    password_chars.extend([alpha_characters[n] for n in raw_binary_offsets[-buffer:]])
    return ''.join(password_chars)


def password_conforming(options: argparse.Namespace) -> str:
    """A password conforming to rules expressed through program options."""
    al = make_alpha_dictionary()
    dg = make_digit_dictionary()
    # We can add options to constrain the punctuation character set, for
    # varying levels of portability.
    punct_chars = []
    if options.punctuation_characters:
        punct_chars.extend([c for c in options.punctuation_characters])
    else:
        punct_chars.extend(chars_in_range('!', '/'))
        punct_chars.extend(chars_in_range(':', '@'))
        punct_chars.extend(chars_in_range('[', '`'))
        punct_chars.extend(chars_in_range('{', '~'))
    pt = make_x_dictionary(punct_chars)

    if options.entropy > 0:
        min_entropy = options.entropy
        have_entropy = options.digits * dg.entropy + options.punctuation * pt.entropy + options.buffer * 2 * al.entropy
        have_len = options.digits + options.punctuation + 2 * options.buffer
        length = max(1, math.ceil((min_entropy - have_entropy) / al.entropy)) + have_len
    else:
        length = options.length

    indices = secret_bytes_list(length, options)
    password_chars = []
    password_chars.extend([dg[n] for n in indices[:options.digits]])
    password_chars.extend([pt[n] for n in indices[options.digits:options.digits + options.punctuation]])
    # Beware that n:-0 is an empty list, which is why we constrain padding to be positive
    password_chars.extend([al[n] for n in indices[options.digits + options.punctuation: -(options.buffer * 2)]])
    buffer_chars = [al[n] for n in indices[-(options.buffer * 2):]]
    random_shuffle(password_chars)
    res = buffer_chars[:options.buffer]
    res.extend(password_chars)
    res.extend(buffer_chars[options.buffer:])
    return ''.join(res)


def load_word_list(name: str, path: pathlib.Path) -> typing.List[str]:
    """Return a diceware style wordlist, loading it if needed."""
    global _CACHED_WORDLISTS
    if name not in _CACHED_WORDLISTS:
        _CACHED_WORDLISTS[name] = load_word_list_raw(path)
    return _CACHED_WORDLISTS[name]


def load_word_list_raw(path: pathlib.Path) -> typing.List[str]:
    """Load a diceware style wordlist."""
    ll: typing.List[str] = []
    for line in path.open():
        # FIXME: better robustness checks here
        if not line:
            continue
        if line[0] not in ('1', '2', '3', '4', '5', '6'):  # how should this handle non-six-sided dice?
            continue
        try:
            ll.append(line.strip().split(None, 1)[1])
        except Exception as e:
            raise ExitError(f'FAILED: {e} in line {line} of {path!r}') from e
    return ll


def load_bitcoin_list(path: pathlib.Path) -> typing.List[str]:
    """Return a bitcoin BIP39 style wordlist, loading it if needed."""
    global _CACHED_BITCOIN_WORDLISTS
    key = str(path)
    if key not in _CACHED_BITCOIN_WORDLISTS:
        _CACHED_BITCOIN_WORDLISTS[key] = load_bitcoin_list_raw(path)
    return _CACHED_BITCOIN_WORDLISTS[key]


def load_bitcoin_list_raw(path: pathlib.Path) -> typing.List[str]:
    """Load a bitcoin BIP39 style wordlist."""
    ll: typing.List[str] = ['' for _ in range(_BITCOIN_BIP39_WORDCOUNT)]
    seen = 0
    for line in path.open():
        if not line:
            continue
        ll[seen] = line.strip()
        seen += 1
    if seen != _BITCOIN_BIP39_WORDCOUNT:
        raise ExitError(f'FAILED: not expected {_BITCOIN_BIP39_WORDCOUNT} entries in {path!r}, found {seen}')
    return ll


def password_dice(options: argparse.Namespace) -> str:
    """Return a diceware style password per program options."""
    wl_name = options.word_list
    DIE_SIDES = 6
    wl = KNOWN_WORDLISTS[wl_name]
    wl_file = options.word_list_dir / wl.file
    if not wl_file.exists():
        raise ExitError(f'missing diceware file {wl_file}')
    word_list = load_word_list(wl_name, wl_file)

    return password_words_from_list(word_list=word_list,
                                    max_int=DIE_SIDES ** wl.rolls - 1,
                                    word_values_count=DIE_SIDES ** wl.rolls,
                                    options=options)


def password_words_from_list(word_list: typing.List[str],
                             max_int: int,
                             word_values_count: int,
                             options: argparse.Namespace) -> str:
    if options.entropy:
        # For bitcoin and skey, word_values_count should be 2048, so per_word is 11
        per_word = math.log2(word_values_count)
        word_count = math.ceil(options.entropy / per_word)
    else:
        word_count = options.length

    words: typing.List[str] = []
    rng = Random_IntBelow_Generator(max_int, options)

    for _ in range(word_count):
        index_int = rng.next()
        try:
            words.append(word_list[index_int])
        except Exception as e:
            raise ExitError(f'bad index {index_int}, max {len(word_list)}') from e

    return options.word_separator.join(words)


def password_skey(options: argparse.Namespace) -> str:
    """Returns a diceware style password using RFC1751 S/Key words."""
    word_list = _RFC1751_SKEY_WORDS
    word_count = len(word_list)
    if word_count != 2048:
        raise Exception(f'invalid _RFC1751_SKEY_WORDS, should be 2048 entries long, is {word_count}')
    return password_words_from_list(word_list=word_list,
                                    max_int=word_count,
                                    word_values_count=word_count,
                                    options=options)


def password_bitcoin(options: argparse.Namespace) -> str:
    """Return a Bitcoin BIP39 style password per program options."""
    wl_file = options.bitcoin_list_dir / options.bitcoin_list
    if not wl_file.exists():
        raise ExitError(f'missing bitcoin file {wl_file}')
    word_list = load_bitcoin_list(wl_file)

    return password_words_from_list(word_list=word_list,
                                    max_int=_BITCOIN_BIP39_WORDCOUNT,  # should be 2048
                                    word_values_count=_BITCOIN_BIP39_WORDCOUNT,
                                    options=options)


def main() -> int:
    """Program main entry-point, excluding exit exception handling."""
    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument('-d', '--digits',
                        type=CountOrRatio, metavar='N',
                        default=CountOrRatio(_DEF_DIGITS_FRAC, base=_DEFAULT_LENGTH),
                        help='How many digits to include [%(default)s]')
    parser.add_argument('-p', '--punctuation',
                        type=CountOrRatio, metavar='M',
                        default=CountOrRatio(_DEF_PUNCTUATION_FRAC, base=_DEFAULT_LENGTH),
                        help='How many punctuation characters to include [%(default)s]')
    parser.add_argument('-P', '--punctuation-characters',
                        type=str, default='', metavar='CHARS',
                        help='Constrain the punctuation characters to these')
    parser.add_argument('-b', '--buffer',
                        type=int, default=_DEF_BUFFER_ALPHA, metavar='PAD',
                        help='How many leading and trailing characters to be pure alphabetic [%(default)s]')
    parser.add_argument('--open',
                        action='store_true', default=False,
                        help='Use a more open approach')
    worder = parser.add_mutually_exclusive_group()
    worder.add_argument('-D', '--dice',
                        action='store_true', default=False,
                        help='Use a diceware passphrase approach')
    parser.add_argument('--word-list',
                        choices=KNOWN_WORDLISTS.keys(), default=None,
                        help='Use diceware and change default wordlist [' + _DEF_WORDLIST + ']')
    parser.add_argument('--word-list-dir',
                        default=_DEF_WORDLISTS_DIR, type=pathlib.Path, metavar='D',
                        help='Directory holding diceware wordlist files [%(default)s]')
    worder.add_argument('-B', '--bitcoin', '--bip39',
                        action='store_true', default=False,
                        help='Make a passphrase using the Bitcoin BIP39 wordlists for dictionaries')
    parser.add_argument('--bitcoin-list-dir',
                        default=_DEF_BITCOIN_DIR, type=pathlib.Path, metavar='D',
                        help='Directory holding bitcoin BIP39 wordlist files [%(default)s]')
    parser.add_argument('--bitcoin-list',
                        default=_DEF_BITCOIN,
                        help='File within --bitcoin-list-dir to use for BIP39 passphrases')
    worder.add_argument('--skey', '--rfc1751',
                        action='store_true', default=False,
                        help='Use RFC 1751 (S/Key) words, but NOT the S/Key algorithm')  # FIXME: should this change
    parser.add_argument('-S', '--word-separator',
                        default=' ', metavar='SEP',
                        help='Separator between words in wordlist passphrases')
    parser.add_argument('-e', '--entropy',
                        type=int, default=0,
                        help=f'Target minimal length password with this many bits of entropy [default: unused; minimum: {_MIN_ENTROPY}]')
    parser.add_argument('--allow-insecure-low-entropy',
                        action='store_true', default=False,
                        help='Allow dangerously weak passwords')
    parser.add_argument('--fixed-nonrandom-hex',
                        type=str, default=None, metavar='H',
                        help='Force the random number to not be random, but parse this hex instead')
    parser.add_argument('length',
                        type=int, default=_DEFAULT_LENGTH, nargs='?',
                        help='How long a password to make [%(default)s]')
    options = parser.parse_args()

    if options.entropy:
        if options.entropy < 0:
            parser.error(f'entropy needs to be positive, not [{options.entropy}]')
        if options.entropy < _MIN_ENTROPY and not options.allow_insecure_low_entropy:
            parser.error(f'entropy of {options.entropy} is less than minimum of {_MIN_ENTROPY}')

    options.digits.base = options.length
    options.punctuation.base = options.length

    # This is replacing default=_DEF_WORDLIST and letting us track that the
    # option was used, so that one option can imply another.
    if options.word_list is not None:
        options.dice = True
    else:
        options.word_list = _DEF_WORDLIST

    if options.dice:
        if not options.word_list_dir.is_dir():
            raise ExitError(f'not a directory: {options.word_list_dir}')
        # NB: for the entropy-based approach, the entropy depends upon the
        # word-list; the number of rolls per word can vary.

        # FIXME: auto-adapt the default min_length so that the argparse does this check for us.
        min_length = 2
        if options.length < min_length and not options.entropy:
            raise ExitError(f'length needs to be at least {min_length}; \'{options.length}\' too small')
        print(password_dice(options))
        return 0

    if options.bitcoin:
        if not options.bitcoin_list:
            raise parser.error('value of --bitcoin-list must not be empty')
        if not options.bitcoin_list_dir.is_dir():
            raise ExitError(f'not a directory: {options.bitcoin_list_dir}')
        # This is very similar in spirit to diceware, but the list of words is supposed to be 2048 each
        min_length = 2
        if options.length < min_length and not options.entropy:
            raise ExitError(f'length needs to be at least {min_length}; \'{options.length}\' too small')
        print(password_bitcoin(options))
        return 0

    if options.skey:
        min_length = 2
        if options.length < min_length and not options.entropy:
            raise ExitError(f'length needs to be at least {min_length}; \'{options.length}\' too small')
        print(password_skey(options))
        return 0

    for numfield in ('digits', 'punctuation'):
        v = getattr(options, numfield)
        if v < 0:
            parser.error(f'field {numfield} should be a non-negative integer, not \'{v}\'')
    for numfield in ('length', 'buffer'):
        # nb: buffer needs to be non-zero to avoid more complexity in offset indicing
        v = getattr(options, numfield)
        if v <= 0:
            parser.error(f'field {numfield} should be a positive integer, not \'{v}\'')

    if options.open:
        min_length = 1 + 2 * options.buffer
    else:
        min_length = 1 + options.digits + options.punctuation + 2 * options.buffer

    if options.length < min_length:
        raise ExitError(f'length needs to be at least {min_length}; \'{options.length}\' too small')

    if options.open:
        print(password_fairly_open(options.entropy, options.length, options.buffer, options))
        return 0

    print(password_conforming(options))
    return 0

# RFC1751 Static Data {{{
_RFC1751_SKEY_WORDS = [
    "A", "ABE", "ACE", "ACT", "AD", "ADA", "ADD",
    "AGO", "AID", "AIM", "AIR", "ALL", "ALP", "AM", "AMY", "AN", "ANA",
    "AND", "ANN", "ANT", "ANY", "APE", "APS", "APT", "ARC", "ARE", "ARK",
    "ARM", "ART", "AS", "ASH", "ASK", "AT", "ATE", "AUG", "AUK", "AVE",
    "AWE", "AWK", "AWL", "AWN", "AX", "AYE", "BAD", "BAG", "BAH", "BAM",
    "BAN", "BAR", "BAT", "BAY", "BE", "BED", "BEE", "BEG", "BEN", "BET",
    "BEY", "BIB", "BID", "BIG", "BIN", "BIT", "BOB", "BOG", "BON", "BOO",
    "BOP", "BOW", "BOY", "BUB", "BUD", "BUG", "BUM", "BUN", "BUS", "BUT",
    "BUY", "BY", "BYE", "CAB", "CAL", "CAM", "CAN", "CAP", "CAR", "CAT",
    "CAW", "COD", "COG", "COL", "CON", "COO", "COP", "COT", "COW", "COY",
    "CRY", "CUB", "CUE", "CUP", "CUR", "CUT", "DAB", "DAD", "DAM", "DAN",
    "DAR", "DAY", "DEE", "DEL", "DEN", "DES", "DEW", "DID", "DIE", "DIG",
    "DIN", "DIP", "DO", "DOE", "DOG", "DON", "DOT", "DOW", "DRY", "DUB",
    "DUD", "DUE", "DUG", "DUN", "EAR", "EAT", "ED", "EEL", "EGG", "EGO",
    "ELI", "ELK", "ELM", "ELY", "EM", "END", "EST", "ETC", "EVA", "EVE",
    "EWE", "EYE", "FAD", "FAN", "FAR", "FAT", "FAY", "FED", "FEE", "FEW",
    "FIB", "FIG", "FIN", "FIR", "FIT", "FLO", "FLY", "FOE", "FOG", "FOR",
    "FRY", "FUM", "FUN", "FUR", "GAB", "GAD", "GAG", "GAL", "GAM", "GAP",
    "GAS", "GAY", "GEE", "GEL", "GEM", "GET", "GIG", "GIL", "GIN", "GO",
    "GOT", "GUM", "GUN", "GUS", "GUT", "GUY", "GYM", "GYP", "HA", "HAD",
    "HAL", "HAM", "HAN", "HAP", "HAS", "HAT", "HAW", "HAY", "HE", "HEM",
    "HEN", "HER", "HEW", "HEY", "HI", "HID", "HIM", "HIP", "HIS", "HIT",
    "HO", "HOB", "HOC", "HOE", "HOG", "HOP", "HOT", "HOW", "HUB", "HUE",
    "HUG", "HUH", "HUM", "HUT", "I", "ICY", "IDA", "IF", "IKE", "ILL",
    "INK", "INN", "IO", "ION", "IQ", "IRA", "IRE", "IRK", "IS", "IT", "ITS",
    "IVY", "JAB", "JAG", "JAM", "JAN", "JAR", "JAW", "JAY", "JET", "JIG",
    "JIM", "JO", "JOB", "JOE", "JOG", "JOT", "JOY", "JUG", "JUT", "KAY",
    "KEG", "KEN", "KEY", "KID", "KIM", "KIN", "KIT", "LA", "LAB", "LAC",
    "LAD", "LAG", "LAM", "LAP", "LAW", "LAY", "LEA", "LED", "LEE", "LEG",
    "LEN", "LEO", "LET", "LEW", "LID", "LIE", "LIN", "LIP", "LIT", "LO",
    "LOB", "LOG", "LOP", "LOS", "LOT", "LOU", "LOW", "LOY", "LUG", "LYE",
    "MA", "MAC", "MAD", "MAE", "MAN", "MAO", "MAP", "MAT", "MAW", "MAY",
    "ME", "MEG", "MEL", "MEN", "MET", "MEW", "MID", "MIN", "MIT", "MOB",
    "MOD", "MOE", "MOO", "MOP", "MOS", "MOT", "MOW", "MUD", "MUG", "MUM",
    "MY", "NAB", "NAG", "NAN", "NAP", "NAT", "NAY", "NE", "NED", "NEE",
    "NET", "NEW", "NIB", "NIL", "NIP", "NIT", "NO", "NOB", "NOD", "NON",
    "NOR", "NOT", "NOV", "NOW", "NU", "NUN", "NUT", "O", "OAF", "OAK",
    "OAR", "OAT", "ODD", "ODE", "OF", "OFF", "OFT", "OH", "OIL", "OK",
    "OLD", "ON", "ONE", "OR", "ORB", "ORE", "ORR", "OS", "OTT", "OUR",
    "OUT", "OVA", "OW", "OWE", "OWL", "OWN", "OX", "PA", "PAD", "PAL",
    "PAM", "PAN", "PAP", "PAR", "PAT", "PAW", "PAY", "PEA", "PEG", "PEN",
    "PEP", "PER", "PET", "PEW", "PHI", "PI", "PIE", "PIN", "PIT", "PLY",
    "PO", "POD", "POE", "POP", "POT", "POW", "PRO", "PRY", "PUB", "PUG",
    "PUN", "PUP", "PUT", "QUO", "RAG", "RAM", "RAN", "RAP", "RAT", "RAW",
    "RAY", "REB", "RED", "REP", "RET", "RIB", "RID", "RIG", "RIM", "RIO",
    "RIP", "ROB", "ROD", "ROE", "RON", "ROT", "ROW", "ROY", "RUB", "RUE",
    "RUG", "RUM", "RUN", "RYE", "SAC", "SAD", "SAG", "SAL", "SAM", "SAN",
    "SAP", "SAT", "SAW", "SAY", "SEA", "SEC", "SEE", "SEN", "SET", "SEW",
    "SHE", "SHY", "SIN", "SIP", "SIR", "SIS", "SIT", "SKI", "SKY", "SLY",
    "SO", "SOB", "SOD", "SON", "SOP", "SOW", "SOY", "SPA", "SPY", "SUB",
    "SUD", "SUE", "SUM", "SUN", "SUP", "TAB", "TAD", "TAG", "TAN", "TAP",
    "TAR", "TEA", "TED", "TEE", "TEN", "THE", "THY", "TIC", "TIE", "TIM",
    "TIN", "TIP", "TO", "TOE", "TOG", "TOM", "TON", "TOO", "TOP", "TOW",
    "TOY", "TRY", "TUB", "TUG", "TUM", "TUN", "TWO", "UN", "UP", "US",
    "USE", "VAN", "VAT", "VET", "VIE", "WAD", "WAG", "WAR", "WAS", "WAY",
    "WE", "WEB", "WED", "WEE", "WET", "WHO", "WHY", "WIN", "WIT", "WOK",
    "WON", "WOO", "WOW", "WRY", "WU", "YAM", "YAP", "YAW", "YE", "YEA",
    "YES", "YET", "YOU", "ABED", "ABEL", "ABET", "ABLE", "ABUT", "ACHE",
    "ACID", "ACME", "ACRE", "ACTA", "ACTS", "ADAM", "ADDS", "ADEN", "AFAR",
    "AFRO", "AGEE", "AHEM", "AHOY", "AIDA", "AIDE", "AIDS", "AIRY", "AJAR",
    "AKIN", "ALAN", "ALEC", "ALGA", "ALIA", "ALLY", "ALMA", "ALOE", "ALSO",
    "ALTO", "ALUM", "ALVA", "AMEN", "AMES", "AMID", "AMMO", "AMOK", "AMOS",
    "AMRA", "ANDY", "ANEW", "ANNA", "ANNE", "ANTE", "ANTI", "AQUA", "ARAB",
    "ARCH", "AREA", "ARGO", "ARID", "ARMY", "ARTS", "ARTY", "ASIA", "ASKS",
    "ATOM", "AUNT", "AURA", "AUTO", "AVER", "AVID", "AVIS", "AVON", "AVOW",
    "AWAY", "AWRY", "BABE", "BABY", "BACH", "BACK", "BADE", "BAIL", "BAIT",
    "BAKE", "BALD", "BALE", "BALI", "BALK", "BALL", "BALM", "BAND", "BANE",
    "BANG", "BANK", "BARB", "BARD", "BARE", "BARK", "BARN", "BARR", "BASE",
    "BASH", "BASK", "BASS", "BATE", "BATH", "BAWD", "BAWL", "BEAD", "BEAK",
    "BEAM", "BEAN", "BEAR", "BEAT", "BEAU", "BECK", "BEEF", "BEEN", "BEER",
    "BEET", "BELA", "BELL", "BELT", "BEND", "BENT", "BERG", "BERN", "BERT",
    "BESS", "BEST", "BETA", "BETH", "BHOY", "BIAS", "BIDE", "BIEN", "BILE",
    "BILK", "BILL", "BIND", "BING", "BIRD", "BITE", "BITS", "BLAB", "BLAT",
    "BLED", "BLEW", "BLOB", "BLOC", "BLOT", "BLOW", "BLUE", "BLUM", "BLUR",
    "BOAR", "BOAT", "BOCA", "BOCK", "BODE", "BODY", "BOGY", "BOHR", "BOIL",
    "BOLD", "BOLO", "BOLT", "BOMB", "BONA", "BOND", "BONE", "BONG", "BONN",
    "BONY", "BOOK", "BOOM", "BOON", "BOOT", "BORE", "BORG", "BORN", "BOSE",
    "BOSS", "BOTH", "BOUT", "BOWL", "BOYD", "BRAD", "BRAE", "BRAG", "BRAN",
    "BRAY", "BRED", "BREW", "BRIG", "BRIM", "BROW", "BUCK", "BUDD", "BUFF",
    "BULB", "BULK", "BULL", "BUNK", "BUNT", "BUOY", "BURG", "BURL", "BURN",
    "BURR", "BURT", "BURY", "BUSH", "BUSS", "BUST", "BUSY", "BYTE", "CADY",
    "CAFE", "CAGE", "CAIN", "CAKE", "CALF", "CALL", "CALM", "CAME", "CANE",
    "CANT", "CARD", "CARE", "CARL", "CARR", "CART", "CASE", "CASH", "CASK",
    "CAST", "CAVE", "CEIL", "CELL", "CENT", "CERN", "CHAD", "CHAR", "CHAT",
    "CHAW", "CHEF", "CHEN", "CHEW", "CHIC", "CHIN", "CHOU", "CHOW", "CHUB",
    "CHUG", "CHUM", "CITE", "CITY", "CLAD", "CLAM", "CLAN", "CLAW", "CLAY",
    "CLOD", "CLOG", "CLOT", "CLUB", "CLUE", "COAL", "COAT", "COCA", "COCK",
    "COCO", "CODA", "CODE", "CODY", "COED", "COIL", "COIN", "COKE", "COLA",
    "COLD", "COLT", "COMA", "COMB", "COME", "COOK", "COOL", "COON", "COOT",
    "CORD", "CORE", "CORK", "CORN", "COST", "COVE", "COWL", "CRAB", "CRAG",
    "CRAM", "CRAY", "CREW", "CRIB", "CROW", "CRUD", "CUBA", "CUBE", "CUFF",
    "CULL", "CULT", "CUNY", "CURB", "CURD", "CURE", "CURL", "CURT", "CUTS",
    "DADE", "DALE", "DAME", "DANA", "DANE", "DANG", "DANK", "DARE", "DARK",
    "DARN", "DART", "DASH", "DATA", "DATE", "DAVE", "DAVY", "DAWN", "DAYS",
    "DEAD", "DEAF", "DEAL", "DEAN", "DEAR", "DEBT", "DECK", "DEED", "DEEM",
    "DEER", "DEFT", "DEFY", "DELL", "DENT", "DENY", "DESK", "DIAL", "DICE",
    "DIED", "DIET", "DIME", "DINE", "DING", "DINT", "DIRE", "DIRT", "DISC",
    "DISH", "DISK", "DIVE", "DOCK", "DOES", "DOLE", "DOLL", "DOLT", "DOME",
    "DONE", "DOOM", "DOOR", "DORA", "DOSE", "DOTE", "DOUG", "DOUR", "DOVE",
    "DOWN", "DRAB", "DRAG", "DRAM", "DRAW", "DREW", "DRUB", "DRUG", "DRUM",
    "DUAL", "DUCK", "DUCT", "DUEL", "DUET", "DUKE", "DULL", "DUMB", "DUNE",
    "DUNK", "DUSK", "DUST", "DUTY", "EACH", "EARL", "EARN", "EASE", "EAST",
    "EASY", "EBEN", "ECHO", "EDDY", "EDEN", "EDGE", "EDGY", "EDIT", "EDNA",
    "EGAN", "ELAN", "ELBA", "ELLA", "ELSE", "EMIL", "EMIT", "EMMA", "ENDS",
    "ERIC", "EROS", "EVEN", "EVER", "EVIL", "EYED", "FACE", "FACT", "FADE",
    "FAIL", "FAIN", "FAIR", "FAKE", "FALL", "FAME", "FANG", "FARM", "FAST",
    "FATE", "FAWN", "FEAR", "FEAT", "FEED", "FEEL", "FEET", "FELL", "FELT",
    "FEND", "FERN", "FEST", "FEUD", "FIEF", "FIGS", "FILE", "FILL", "FILM",
    "FIND", "FINE", "FINK", "FIRE", "FIRM", "FISH", "FISK", "FIST", "FITS",
    "FIVE", "FLAG", "FLAK", "FLAM", "FLAT", "FLAW", "FLEA", "FLED", "FLEW",
    "FLIT", "FLOC", "FLOG", "FLOW", "FLUB", "FLUE", "FOAL", "FOAM", "FOGY",
    "FOIL", "FOLD", "FOLK", "FOND", "FONT", "FOOD", "FOOL", "FOOT", "FORD",
    "FORE", "FORK", "FORM", "FORT", "FOSS", "FOUL", "FOUR", "FOWL", "FRAU",
    "FRAY", "FRED", "FREE", "FRET", "FREY", "FROG", "FROM", "FUEL", "FULL",
    "FUME", "FUND", "FUNK", "FURY", "FUSE", "FUSS", "GAFF", "GAGE", "GAIL",
    "GAIN", "GAIT", "GALA", "GALE", "GALL", "GALT", "GAME", "GANG", "GARB",
    "GARY", "GASH", "GATE", "GAUL", "GAUR", "GAVE", "GAWK", "GEAR", "GELD",
    "GENE", "GENT", "GERM", "GETS", "GIBE", "GIFT", "GILD", "GILL", "GILT",
    "GINA", "GIRD", "GIRL", "GIST", "GIVE", "GLAD", "GLEE", "GLEN", "GLIB",
    "GLOB", "GLOM", "GLOW", "GLUE", "GLUM", "GLUT", "GOAD", "GOAL", "GOAT",
    "GOER", "GOES", "GOLD", "GOLF", "GONE", "GONG", "GOOD", "GOOF", "GORE",
    "GORY", "GOSH", "GOUT", "GOWN", "GRAB", "GRAD", "GRAY", "GREG", "GREW",
    "GREY", "GRID", "GRIM", "GRIN", "GRIT", "GROW", "GRUB", "GULF", "GULL",
    "GUNK", "GURU", "GUSH", "GUST", "GWEN", "GWYN", "HAAG", "HAAS", "HACK",
    "HAIL", "HAIR", "HALE", "HALF", "HALL", "HALO", "HALT", "HAND", "HANG",
    "HANK", "HANS", "HARD", "HARK", "HARM", "HART", "HASH", "HAST", "HATE",
    "HATH", "HAUL", "HAVE", "HAWK", "HAYS", "HEAD", "HEAL", "HEAR", "HEAT",
    "HEBE", "HECK", "HEED", "HEEL", "HEFT", "HELD", "HELL", "HELM", "HERB",
    "HERD", "HERE", "HERO", "HERS", "HESS", "HEWN", "HICK", "HIDE", "HIGH",
    "HIKE", "HILL", "HILT", "HIND", "HINT", "HIRE", "HISS", "HIVE", "HOBO",
    "HOCK", "HOFF", "HOLD", "HOLE", "HOLM", "HOLT", "HOME", "HONE", "HONK",
    "HOOD", "HOOF", "HOOK", "HOOT", "HORN", "HOSE", "HOST", "HOUR", "HOVE",
    "HOWE", "HOWL", "HOYT", "HUCK", "HUED", "HUFF", "HUGE", "HUGH", "HUGO",
    "HULK", "HULL", "HUNK", "HUNT", "HURD", "HURL", "HURT", "HUSH", "HYDE",
    "HYMN", "IBIS", "ICON", "IDEA", "IDLE", "IFFY", "INCA", "INCH", "INTO",
    "IONS", "IOTA", "IOWA", "IRIS", "IRMA", "IRON", "ISLE", "ITCH", "ITEM",
    "IVAN", "JACK", "JADE", "JAIL", "JAKE", "JANE", "JAVA", "JEAN", "JEFF",
    "JERK", "JESS", "JEST", "JIBE", "JILL", "JILT", "JIVE", "JOAN", "JOBS",
    "JOCK", "JOEL", "JOEY", "JOHN", "JOIN", "JOKE", "JOLT", "JOVE", "JUDD",
    "JUDE", "JUDO", "JUDY", "JUJU", "JUKE", "JULY", "JUNE", "JUNK", "JUNO",
    "JURY", "JUST", "JUTE", "KAHN", "KALE", "KANE", "KANT", "KARL", "KATE",
    "KEEL", "KEEN", "KENO", "KENT", "KERN", "KERR", "KEYS", "KICK", "KILL",
    "KIND", "KING", "KIRK", "KISS", "KITE", "KLAN", "KNEE", "KNEW", "KNIT",
    "KNOB", "KNOT", "KNOW", "KOCH", "KONG", "KUDO", "KURD", "KURT", "KYLE",
    "LACE", "LACK", "LACY", "LADY", "LAID", "LAIN", "LAIR", "LAKE", "LAMB",
    "LAME", "LAND", "LANE", "LANG", "LARD", "LARK", "LASS", "LAST", "LATE",
    "LAUD", "LAVA", "LAWN", "LAWS", "LAYS", "LEAD", "LEAF", "LEAK", "LEAN",
    "LEAR", "LEEK", "LEER", "LEFT", "LEND", "LENS", "LENT", "LEON", "LESK",
    "LESS", "LEST", "LETS", "LIAR", "LICE", "LICK", "LIED", "LIEN", "LIES",
    "LIEU", "LIFE", "LIFT", "LIKE", "LILA", "LILT", "LILY", "LIMA", "LIMB",
    "LIME", "LIND", "LINE", "LINK", "LINT", "LION", "LISA", "LIST", "LIVE",
    "LOAD", "LOAF", "LOAM", "LOAN", "LOCK", "LOFT", "LOGE", "LOIS", "LOLA",
    "LONE", "LONG", "LOOK", "LOON", "LOOT", "LORD", "LORE", "LOSE", "LOSS",
    "LOST", "LOUD", "LOVE", "LOWE", "LUCK", "LUCY", "LUGE", "LUKE", "LULU",
    "LUND", "LUNG", "LURA", "LURE", "LURK", "LUSH", "LUST", "LYLE", "LYNN",
    "LYON", "LYRA", "MACE", "MADE", "MAGI", "MAID", "MAIL", "MAIN", "MAKE",
    "MALE", "MALI", "MALL", "MALT", "MANA", "MANN", "MANY", "MARC", "MARE",
    "MARK", "MARS", "MART", "MARY", "MASH", "MASK", "MASS", "MAST", "MATE",
    "MATH", "MAUL", "MAYO", "MEAD", "MEAL", "MEAN", "MEAT", "MEEK", "MEET",
    "MELD", "MELT", "MEMO", "MEND", "MENU", "MERT", "MESH", "MESS", "MICE",
    "MIKE", "MILD", "MILE", "MILK", "MILL", "MILT", "MIMI", "MIND", "MINE",
    "MINI", "MINK", "MINT", "MIRE", "MISS", "MIST", "MITE", "MITT", "MOAN",
    "MOAT", "MOCK", "MODE", "MOLD", "MOLE", "MOLL", "MOLT", "MONA", "MONK",
    "MONT", "MOOD", "MOON", "MOOR", "MOOT", "MORE", "MORN", "MORT", "MOSS",
    "MOST", "MOTH", "MOVE", "MUCH", "MUCK", "MUDD", "MUFF", "MULE", "MULL",
    "MURK", "MUSH", "MUST", "MUTE", "MUTT", "MYRA", "MYTH", "NAGY", "NAIL",
    "NAIR", "NAME", "NARY", "NASH", "NAVE", "NAVY", "NEAL", "NEAR", "NEAT",
    "NECK", "NEED", "NEIL", "NELL", "NEON", "NERO", "NESS", "NEST", "NEWS",
    "NEWT", "NIBS", "NICE", "NICK", "NILE", "NINA", "NINE", "NOAH", "NODE",
    "NOEL", "NOLL", "NONE", "NOOK", "NOON", "NORM", "NOSE", "NOTE", "NOUN",
    "NOVA", "NUDE", "NULL", "NUMB", "OATH", "OBEY", "OBOE", "ODIN", "OHIO",
    "OILY", "OINT", "OKAY", "OLAF", "OLDY", "OLGA", "OLIN", "OMAN", "OMEN",
    "OMIT", "ONCE", "ONES", "ONLY", "ONTO", "ONUS", "ORAL", "ORGY", "OSLO",
    "OTIS", "OTTO", "OUCH", "OUST", "OUTS", "OVAL", "OVEN", "OVER", "OWLY",
    "OWNS", "QUAD", "QUIT", "QUOD", "RACE", "RACK", "RACY", "RAFT", "RAGE",
    "RAID", "RAIL", "RAIN", "RAKE", "RANK", "RANT", "RARE", "RASH", "RATE",
    "RAVE", "RAYS", "READ", "REAL", "REAM", "REAR", "RECK", "REED", "REEF",
    "REEK", "REEL", "REID", "REIN", "RENA", "REND", "RENT", "REST", "RICE",
    "RICH", "RICK", "RIDE", "RIFT", "RILL", "RIME", "RING", "RINK", "RISE",
    "RISK", "RITE", "ROAD", "ROAM", "ROAR", "ROBE", "ROCK", "RODE", "ROIL",
    "ROLL", "ROME", "ROOD", "ROOF", "ROOK", "ROOM", "ROOT", "ROSA", "ROSE",
    "ROSS", "ROSY", "ROTH", "ROUT", "ROVE", "ROWE", "ROWS", "RUBE", "RUBY",
    "RUDE", "RUDY", "RUIN", "RULE", "RUNG", "RUNS", "RUNT", "RUSE", "RUSH",
    "RUSK", "RUSS", "RUST", "RUTH", "SACK", "SAFE", "SAGE", "SAID", "SAIL",
    "SALE", "SALK", "SALT", "SAME", "SAND", "SANE", "SANG", "SANK", "SARA",
    "SAUL", "SAVE", "SAYS", "SCAN", "SCAR", "SCAT", "SCOT", "SEAL", "SEAM",
    "SEAR", "SEAT", "SEED", "SEEK", "SEEM", "SEEN", "SEES", "SELF", "SELL",
    "SEND", "SENT", "SETS", "SEWN", "SHAG", "SHAM", "SHAW", "SHAY", "SHED",
    "SHIM", "SHIN", "SHOD", "SHOE", "SHOT", "SHOW", "SHUN", "SHUT", "SICK",
    "SIDE", "SIFT", "SIGH", "SIGN", "SILK", "SILL", "SILO", "SILT", "SINE",
    "SING", "SINK", "SIRE", "SITE", "SITS", "SITU", "SKAT", "SKEW", "SKID",
    "SKIM", "SKIN", "SKIT", "SLAB", "SLAM", "SLAT", "SLAY", "SLED", "SLEW",
    "SLID", "SLIM", "SLIT", "SLOB", "SLOG", "SLOT", "SLOW", "SLUG", "SLUM",
    "SLUR", "SMOG", "SMUG", "SNAG", "SNOB", "SNOW", "SNUB", "SNUG", "SOAK",
    "SOAR", "SOCK", "SODA", "SOFA", "SOFT", "SOIL", "SOLD", "SOME", "SONG",
    "SOON", "SOOT", "SORE", "SORT", "SOUL", "SOUR", "SOWN", "STAB", "STAG",
    "STAN", "STAR", "STAY", "STEM", "STEW", "STIR", "STOW", "STUB", "STUN",
    "SUCH", "SUDS", "SUIT", "SULK", "SUMS", "SUNG", "SUNK", "SURE", "SURF",
    "SWAB", "SWAG", "SWAM", "SWAN", "SWAT", "SWAY", "SWIM", "SWUM", "TACK",
    "TACT", "TAIL", "TAKE", "TALE", "TALK", "TALL", "TANK", "TASK", "TATE",
    "TAUT", "TEAL", "TEAM", "TEAR", "TECH", "TEEM", "TEEN", "TEET", "TELL",
    "TEND", "TENT", "TERM", "TERN", "TESS", "TEST", "THAN", "THAT", "THEE",
    "THEM", "THEN", "THEY", "THIN", "THIS", "THUD", "THUG", "TICK", "TIDE",
    "TIDY", "TIED", "TIER", "TILE", "TILL", "TILT", "TIME", "TINA", "TINE",
    "TINT", "TINY", "TIRE", "TOAD", "TOGO", "TOIL", "TOLD", "TOLL", "TONE",
    "TONG", "TONY", "TOOK", "TOOL", "TOOT", "TORE", "TORN", "TOTE", "TOUR",
    "TOUT", "TOWN", "TRAG", "TRAM", "TRAY", "TREE", "TREK", "TRIG", "TRIM",
    "TRIO", "TROD", "TROT", "TROY", "TRUE", "TUBA", "TUBE", "TUCK", "TUFT",
    "TUNA", "TUNE", "TUNG", "TURF", "TURN", "TUSK", "TWIG", "TWIN", "TWIT",
    "ULAN", "UNIT", "URGE", "USED", "USER", "USES", "UTAH", "VAIL", "VAIN",
    "VALE", "VARY", "VASE", "VAST", "VEAL", "VEDA", "VEIL", "VEIN", "VEND",
    "VENT", "VERB", "VERY", "VETO", "VICE", "VIEW", "VINE", "VISE", "VOID",
    "VOLT", "VOTE", "WACK", "WADE", "WAGE", "WAIL", "WAIT", "WAKE", "WALE",
    "WALK", "WALL", "WALT", "WAND", "WANE", "WANG", "WANT", "WARD", "WARM",
    "WARN", "WART", "WASH", "WAST", "WATS", "WATT", "WAVE", "WAVY", "WAYS",
    "WEAK", "WEAL", "WEAN", "WEAR", "WEED", "WEEK", "WEIR", "WELD", "WELL",
    "WELT", "WENT", "WERE", "WERT", "WEST", "WHAM", "WHAT", "WHEE", "WHEN",
    "WHET", "WHOA", "WHOM", "WICK", "WIFE", "WILD", "WILL", "WIND", "WINE",
    "WING", "WINK", "WINO", "WIRE", "WISE", "WISH", "WITH", "WOLF", "WONT",
    "WOOD", "WOOL", "WORD", "WORE", "WORK", "WORM", "WORN", "WOVE", "WRIT",
    "WYNN", "YALE", "YANG", "YANK", "YARD", "YARN", "YAWL", "YAWN", "YEAH",
    "YEAR", "YELL", "YOGA", "YOKE"
]
# RFC1751 Static Data }}}

if __name__ == '__main__':
    try:
        rv = main()
        sys.exit(rv)
    except ExitError as e:
        argv0 = pathlib.Path(sys.argv[0]).name
        if argv0.endswith('.py'):
            argv0 = argv0[:-3]
        print('{}: {}'.format(argv0, e), file=sys.stderr)
        sys.exit(1)

# vim: set ft=python sw=4 expandtab foldmethod=marker :