Add support for multiple mnemonic wordlist

Added Wordlist class and registry
Moved mnemonic encoding/decoding logic from Seed to Wordlist

monero/wordlists/__init__.py

@@ -1 +1,2 @@
-from . import english
+from .wordlist import get_wordlist, list_wordlists
+from .english import English

monero/wordlists/wordlist.py

@@ -0,0 +1,111 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import logging
+from binascii import crc32
+
+from six import with_metaclass
+
+
+WORDLISTS = {}
+_log = logging.getLogger(__name__)
+
+
+class WordlistType(type):
+    def __new__(cls, name, bases, attrs):
+        if bases:
+            if 'language_name' not in attrs:
+                raise TypeError("Missing language_name for {0}".format(name))
+            if 'unique_prefix_length' not in attrs:
+                raise TypeError("Missing 'unique_prefix_length' for {0}".format(name))
+            if 'word_list' not in attrs:
+                raise TypeError("Missing 'word_list' for {0}".format(name))
+
+            if 'english_language_name' not in attrs:
+                _log.warn("No 'english_language_name' for {0} using '{1}'".format(name, language_name))
+                attrs['english_language_name'] = attrs['language_name']
+
+            if len(attrs['word_list']) != 1626:
+                raise TypeError("Wrong word list length for {0}".format(name))
+
+        new_cls = super(WordlistType, cls).__new__(cls, name, bases, attrs)
+
+        if bases:
+            WORDLISTS[new_cls.english_language_name] = new_cls
+
+        return new_cls
+
+
+class Wordlist(with_metaclass(WordlistType)):
+    n = 1626
+
+    @classmethod
+    def encode(cls, hex):
+        """Convert hexadecimal string to mnemonic word representation with checksum.
+        """
+        out = []
+        for i in range(len(hex) // 8):
+            word = endian_swap(hex[8*i:8*i+8])
+            x = int(word, 16)
+            w1 = x % cls.n
+            w2 = (x // cls.n + w1) % cls.n
+            w3 = (x // cls.n // cls.n + w2) % cls.n
+            out += [cls.word_list[w1], cls.word_list[w2], cls.word_list[w3]]
+        checksum = cls.get_checksum(" ".join(out))
+        out.append(checksum)
+        return " ".join(out)
+
+    @classmethod
+    def decode(cls, phrase):
+        """Calculate hexadecimal representation of the phrase.
+        """
+        phrase = phrase.split(" ")
+        out = ""
+        for i in range(len(phrase) // 3):
+            word1, word2, word3 = phrase[3*i:3*i+3]
+            w1 = cls.word_list.index(word1)
+            w2 = cls.word_list.index(word2) % cls.n
+            w3 = cls.word_list.index(word3) % cls.n
+            x = w1 + cls.n *((w2 - w1) % cls.n) + cls.n * cls.n * ((w3 - w2) % cls.n)
+            out += endian_swap("%08x" % x)
+        return out
+
+    @classmethod
+    def get_checksum(cls, phrase):
+        """Given a mnemonic word string, return a string of the computed checksum.
+
+        :rtype: str
+        """
+        phrase_split = phrase.split(" ")
+        if len(phrase_split) < 12:
+            raise ValueError("Invalid mnemonic phrase")
+        if len(phrase_split) > 13:
+            # Standard format
+            phrase = phrase_split[:24]
+        else:
+            # MyMonero format
+            phrase = phrase_split[:12]
+        wstr = "".join(word[:cls.unique_prefix_length] for word in phrase)
+        wstr = bytearray(wstr.encode('utf-8'))
+        z = ((crc32(wstr) & 0xffffffff) ^ 0xffffffff ) >> 0
+        z2 = ((z ^ 0xffffffff) >> 0) % len(phrase)
+        return phrase_split[z2]
+
+
+def get_wordlist(name):
+    try:
+        return WORDLISTS[name]
+    except KeyError:
+        raise ValueError("No such word list")
+
+
+def list_wordlists():
+    return WORDLISTS.keys()
+
+
+def endian_swap(word):
+    """Given any string, swap bits and return the result.
+
+    :rtype: str
+    """
+    return "".join([word[i:i+2] for i in [6, 4, 2, 0]])