text: #!/usr/bin/env python
  #
  # Electrum - lightweight Bitcoin client
  # Copyright (C) 2014 Thomas Voegtlin
  #
  # Permission is hereby granted, free of charge, to any person
  # obtaining a copy of this software and associated documentation files
  # (the "Software"), to deal in the Software without restriction,
  # including without limitation the rights to use, copy, modify, merge,
  # publish, distribute, sublicense, and/or sell copies of the Software,
  # and to permit persons to whom the Software is furnished to do so,
  # subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  import os
  import math
  import hashlib
  import unicodedata
  import string
  from typing import Sequence, Dict
  from types import MappingProxyType
  
  from .util import resource_path, bfh, randrange
  from .crypto import hmac_oneshot
  from . import version
  from .logging import Logger
  
  
  # 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 normalize_text(seed: str) -> str:
      # normalize
      seed = unicodedata.normalize('NFKD', 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
  
  
  _WORDLIST_CACHE = {}  # type: Dict[str, Wordlist]
  
  
  class Wordlist(tuple):
  
      def __init__(self, words: Sequence[str]):
          super().__init__()
          index_from_word = {w: i for i, w in enumerate(words)}
          self._index_from_word = MappingProxyType(index_from_word)  # no mutation
  
      def index(self, word, start=None, stop=None) -> int:
          try:
              return self._index_from_word[word]
          except KeyError as e:
              raise ValueError from e
  
      def __contains__(self, word) -> bool:
          try:
              self.index(word)
          except ValueError:
              return False
          else:
              return True
  
      @classmethod
      def from_file(cls, filename) -> 'Wordlist':
          path = resource_path('wordlist', filename)
          if path not in _WORDLIST_CACHE:
              with open(path, 'r', encoding='utf-8') as f:
                  s = f.read().strip()
              s = unicodedata.normalize('NFKD', s)
              lines = s.split('\n')
              words = []
              for line in lines:
                  line = line.split('#')[0]
                  line = line.strip(' \r')
                  assert ' ' not in line
                  if line:
                      words.append(line)
  
              _WORDLIST_CACHE[path] = Wordlist(words)
          return _WORDLIST_CACHE[path]
  
  
  filenames = {
      'en':'english.txt',
      'es':'spanish.txt',
      'ja':'japanese.txt',
      'pt':'portuguese.txt',
      'zh':'chinese_simplified.txt'
  }
  
  
  class Mnemonic(Logger):
      # Seed derivation does not follow BIP39
      # Mnemonic phrase uses a hash based checksum, instead of a wordlist-dependent checksum
  
      def __init__(self, lang=None):
          Logger.__init__(self)
          lang = lang or 'en'
          self.logger.info(f'language {lang}')
          filename = filenames.get(lang[0:2], 'english.txt')
          self.wordlist = Wordlist.from_file(filename)
          self.logger.info(f"wordlist has {len(self.wordlist)} words")
  
      @classmethod
      def mnemonic_to_seed(self, mnemonic, passphrase) -> bytes:
          PBKDF2_ROUNDS = 2048
          mnemonic = normalize_text(mnemonic)
          passphrase = passphrase or ''
          passphrase = normalize_text(passphrase)
          return hashlib.pbkdf2_hmac('sha512', mnemonic.encode('utf-8'), b'mnemonic' + passphrase.encode('utf-8'), iterations = PBKDF2_ROUNDS)
  
      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 make_seed(self, seed_type=None, *, num_bits=132) -> str:
          from .keystore import bip39_is_checksum_valid
          if seed_type is None:
              seed_type = 'segwit'
          prefix = version.seed_prefix(seed_type)
          # increase num_bits in order to obtain a uniform distribution for the last word
          bpw = math.log(len(self.wordlist), 2)
          # rounding
          n = int(math.ceil(num_bits/bpw) * bpw)
          self.logger.info(f"make_seed. prefix: '{prefix}', entropy: {n} bits")
          entropy = 1
          while entropy < pow(2, n - bpw):
              # try again if seed would not contain enough words
              entropy = randrange(pow(2, n))
          nonce = 0
          while True:
              nonce += 1
              i = entropy + nonce
              seed = self.mnemonic_encode(i)
              if i != self.mnemonic_decode(seed):
                  raise Exception('Cannot extract same entropy from mnemonic!')
              if is_old_seed(seed):
                  continue
              # Make sure the mnemonic we generate is not also a valid bip39 seed
              # by accident. Note that this test has not always been done historically,
              # so it cannot be relied upon.
              if bip39_is_checksum_valid(seed, wordlist=self.wordlist) == (True, True):
                  continue
              if is_new_seed(seed, prefix):
                  break
          self.logger.info(f'{len(seed.split())} words')
          return seed
  
  
  def is_new_seed(x: str, prefix=version.SEED_PREFIX) -> bool:
      x = normalize_text(x)
      s = hmac_oneshot(b"Seed version", x.encode('utf8'), hashlib.sha512).hex()
      return s.startswith(prefix)
  
  
  def is_old_seed(seed: str) -> bool:
      from . import old_mnemonic
      seed = normalize_text(seed)
      words = seed.split()
      try:
          # checks here are deliberately left weak for legacy reasons, see #3149
          old_mnemonic.mn_decode(words)
          uses_electrum_words = True
      except Exception:
          uses_electrum_words = False
      try:
          seed = bfh(seed)
          is_hex = (len(seed) == 16 or len(seed) == 32)
      except Exception:
          is_hex = False
      return is_hex or (uses_electrum_words and (len(words) == 12 or len(words) == 24))
  
  
  def is_hardware_seed(seed: str) -> bool:
      seed = normalize_text(seed)
      words = seed.split()
      return len(words) == 24
  
  
  def seed_type(x: str) -> str:
      if is_old_seed(x):
          return 'old'
      elif is_new_seed(x):
          return 'standard'
      elif is_new_seed(x, version.SEED_PREFIX_SW):
          return 'segwit'
      elif is_hardware_seed(x):
          return 'standard'
      # elif is_new_seed(x, version.SEED_PREFIX_2FA):
      #     return '2fa'
      # elif is_new_seed(x, version.SEED_PREFIX_2FA_SW):
      #     return '2fa_segwit'
      return ''
  
  
  def is_seed(x: str) -> bool:
      return bool(seed_type(x))
  
  
  def is_any_2fa_seed_type(seed_type: str) -> bool:
      return False
      # return seed_type in ['2fa', '2fa_segwit']
  