electrum/lib/mnemonic.py

#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2014 Thomas Voegtlin
#
# 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 os
import hmac
import math
import hashlib
import unicodedata
import string

import ecdsa
import pbkdf2

from util import print_error
from bitcoin import is_old_seed, is_new_seed
import version
import i18n

# http://www.asahi-net.or.jp/~ax2s-kmtn/ref/unicode/e_asia.html
CJK_INTERVALS = [
    (0x4E00, 0x9FFF, 'CJK Unified Ideographs'),
    (0x3400, 0x4DBF, 'CJK Unified Ideographs Extension A'),
    (0x20000, 0x2A6DF, 'CJK Unified Ideographs Extension B'),
    (0x2A700, 0x2B73F, 'CJK Unified Ideographs Extension C'),
    (0x2B740, 0x2B81F, 'CJK Unified Ideographs Extension D'),
    (0xF900, 0xFAFF, 'CJK Compatibility Ideographs'),
    (0x2F800, 0x2FA1D, 'CJK Compatibility Ideographs Supplement'),
    (0x3190, 0x319F , 'Kanbun'),
    (0x2E80, 0x2EFF, 'CJK Radicals Supplement'),
    (0x2F00, 0x2FDF, 'CJK Radicals'),
    (0x31C0, 0x31EF, 'CJK Strokes'),
    (0x2FF0, 0x2FFF, 'Ideographic Description Characters'),
    (0xE0100, 0xE01EF, 'Variation Selectors Supplement'),
    (0x3100, 0x312F, 'Bopomofo'),
    (0x31A0, 0x31BF, 'Bopomofo Extended'),
    (0xFF00, 0xFFEF, 'Halfwidth and Fullwidth Forms'),
    (0x3040, 0x309F, 'Hiragana'),
    (0x30A0, 0x30FF, 'Katakana'),
    (0x31F0, 0x31FF, 'Katakana Phonetic Extensions'),
    (0x1B000, 0x1B0FF, 'Kana Supplement'),
    (0xAC00, 0xD7AF, 'Hangul Syllables'),
    (0x1100, 0x11FF, 'Hangul Jamo'),
    (0xA960, 0xA97F, 'Hangul Jamo Extended A'),
    (0xD7B0, 0xD7FF, 'Hangul Jamo Extended B'),
    (0x3130, 0x318F, 'Hangul Compatibility Jamo'),
    (0xA4D0, 0xA4FF, 'Lisu'),
    (0x16F00, 0x16F9F, 'Miao'),
    (0xA000, 0xA48F, 'Yi Syllables'),
    (0xA490, 0xA4CF, 'Yi Radicals'),
]

def is_CJK(c):
    n = ord(c)
    for imin,imax,name in CJK_INTERVALS:
        if n>=imin and n<=imax: return True
    return False


def prepare_seed(seed):
    # normalize
    seed = unicodedata.normalize('NFKD', unicode(seed))
    # lower
    seed = seed.lower()
    # remove accents
    seed = u''.join([c for c in seed if not unicodedata.combining(c)])
    # normalize whitespaces
    seed = u' '.join(seed.split())
    # remove whitespaces between CJK
    seed = u''.join([seed[i] for i in range(len(seed)) if not (seed[i] in string.whitespace and is_CJK(seed[i-1]) and is_CJK(seed[i+1]))])
    return seed


filenames = {
    'en':'english.txt',
    'es':'spanish.txt',
    'ja':'japanese.txt',
    'pt':'portuguese.txt',
    'zh':'chinese_simplified.txt'
}



class Mnemonic(object):
    # Seed derivation no longer follows BIP39
    # Mnemonic phrase uses a hash based checksum, instead of a wordlist-dependent checksum

    def __init__(self, lang=None):
        if lang in [None, '']:
            lang = i18n.language.info().get('language', 'en')
        print_error('language', lang)
        filename = filenames.get(lang[0:2], 'english.txt')
        path = os.path.join(os.path.dirname(__file__), 'wordlist', filename)
        s = open(path,'r').read().strip()
        s = unicodedata.normalize('NFKD', s.decode('utf8'))
        lines = s.split('\n')
        self.wordlist = []
        for line in lines:
            line = line.split('#')[0]
            line = line.strip(' \r')
            assert ' ' not in line
            if line:
                self.wordlist.append(line)
        print_error("wordlist has %d words"%len(self.wordlist))

    @classmethod
    def mnemonic_to_seed(self, mnemonic, passphrase):
        PBKDF2_ROUNDS = 2048
        mnemonic = prepare_seed(mnemonic)
        return pbkdf2.PBKDF2(mnemonic, 'electrum' + passphrase, iterations = PBKDF2_ROUNDS, macmodule = hmac, digestmodule = hashlib.sha512).read(64)

    def mnemonic_encode(self, i):
        n = len(self.wordlist)
        words = []
        while i:
            x = i%n
            i = i/n
            words.append(self.wordlist[x])
        return ' '.join(words)

    def get_suggestions(self, prefix):
        for w in self.wordlist:
            if w.startswith(prefix):
                yield w

    def mnemonic_decode(self, seed):
        n = len(self.wordlist)
        words = seed.split()
        i = 0
        while words:
            w = words.pop()
            k = self.wordlist.index(w)
            i = i*n + k
        return i

    def check_seed(self, seed, custom_entropy):
        assert is_new_seed(seed)
        i = self.mnemonic_decode(seed)
        return i % custom_entropy == 0

    def make_seed(self, num_bits=128, prefix=version.SEED_PREFIX, custom_entropy=1):
        n = int(math.ceil(math.log(custom_entropy,2)))
        # bits of entropy used by the prefix
        k = len(prefix)*4
        # we add at least 16 bits
        n_added = max(16, k + num_bits - n)
        print_error("make_seed", prefix, "adding %d bits"%n_added)
        my_entropy = ecdsa.util.randrange( pow(2, n_added) )
        nonce = 0
        while True:
            nonce += 1
            i = custom_entropy * (my_entropy + nonce)
            seed = self.mnemonic_encode(i)
            assert i == self.mnemonic_decode(seed)
            if is_old_seed(seed):
                continue
            if is_new_seed(seed, prefix):
                break
        print_error('%d words'%len(seed.split()))
        return seed