monero/src/mnemonics/electrum-words.cpp

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// Copyright (c) 2014, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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/*!
* \file electrum-words.cpp
*
* \brief Mnemonic seed generation and wallet restoration from them.
*
* This file and its header file are for translating Electrum-style word lists
* into their equivalent byte representations for cross-compatibility with
* that method of "backing up" one's wallet keys.
*/
#include <string>
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#include <cassert>
#include <map>
#include <cstdint>
#include <vector>
#include <boost/algorithm/string.hpp>
#include "crypto/crypto.h" // for declaration of crypto::secret_key
#include <fstream>
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#include "mnemonics/electrum-words.h"
#include <stdexcept>
#include <boost/filesystem.hpp>
namespace
{
int num_words = 0;
std::map<std::string,uint32_t> words_map;
std::vector<std::string> words_array;
bool is_old_style_mnemonics = false;
const std::string WORD_LISTS_DIRECTORY = "wordlists";
const std::string LANGUAGES_DIRECTORY = "languages";
const std::string OLD_WORD_FILE = "old-word-list";
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/*!
* Tells if the module hasn't been initialized with a word list file.
* \return Whether the module hasn't been initialized with a word list file.
*/
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bool is_uninitialized()
{
return num_words == 0 ? true : false;
}
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/*!
* Create word list map and array data structres for use during inter-conversion between
* words and secret key.
* \param word_file Path to the word list file from pwd.
*/
void create_data_structures(const std::string &word_file)
{
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words_array.clear();
words_map.clear();
num_words = 0;
std::ifstream input_stream;
input_stream.open(word_file.c_str(), std::ifstream::in);
if (!input_stream)
throw std::runtime_error(std::string("Word list file couldn't be opened."));
std::string word;
while (input_stream >> word)
{
words_array.push_back(word);
words_map[word] = num_words;
num_words++;
}
input_stream.close();
}
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/*!
* Tells if all the words passed in wlist was present in current word list file.
* \param wlist List of words to match.
* \return Whether they were all present or not.
*/
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bool word_list_file_match(const std::vector<std::string> &wlist)
{
for (std::vector<std::string>::const_iterator it = wlist.begin(); it != wlist.end(); it++)
{
if (words_map.count(*it) == 0)
{
return false;
}
}
return true;
}
}
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/*!
* \namespace crypto
*/
namespace crypto
{
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/*!
* \namespace ElectrumWords
*
* \brief Mnemonic seed word generation and wallet restoration.
*/
namespace ElectrumWords
{
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/*!
* \brief Called to initialize it work with a word list file.
* \param language Language of the word list file.
* \param old_word_list Whether it is to use the old style word list file.
*/
void init(const std::string &language, bool old_word_list)
{
if (old_word_list)
{
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// Use the old word list file if told to.
create_data_structures(WORD_LISTS_DIRECTORY + '/' + OLD_WORD_FILE);
is_old_style_mnemonics = true;
}
else
{
create_data_structures(WORD_LISTS_DIRECTORY + '/' + LANGUAGES_DIRECTORY + '/' + language);
is_old_style_mnemonics = false;
}
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if (num_words == 0)
{
throw std::runtime_error(std::string("Word list file is empty: ") +
(old_word_list ? OLD_WORD_FILE : (LANGUAGES_DIRECTORY + '/' + language)));
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}
}
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/*!
* \brief If the module is currenly using an old style word list.
* \return Whether it is currenly using an old style word list.
*/
bool get_is_old_style_mnemonics()
{
if (is_uninitialized())
{
throw std::runtime_error("ElectrumWords hasn't been initialized with a word list yet.");
}
return is_old_style_mnemonics;
}
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/*!
* \brief Converts seed words to bytes (secret key).
* \param words String containing the words separated by spaces.
* \param dst To put the secret key restored from the words.
* \return false if not a multiple of 3 words, or if word is not in the words list
*/
bool words_to_bytes(const std::string& words, crypto::secret_key& dst)
{
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std::vector<std::string> wlist;
boost::split(wlist, words, boost::is_any_of(" "));
std::vector<std::string> languages;
get_language_list(languages);
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// Try to find a word list file that contains all the words in the word list.
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std::vector<std::string>::iterator it;
for (it = languages.begin(); it != languages.end(); it++)
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{
init(*it);
if (word_list_file_match(wlist))
{
break;
}
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}
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// If no such file was found, see if the old style word list file has them all.
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if (it == languages.end())
{
init("", true);
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if (!word_list_file_match(wlist))
{
return false;
}
}
int n = num_words;
// error on non-compliant word list
if (wlist.size() != 12 && wlist.size() != 24) return false;
for (unsigned int i=0; i < wlist.size() / 3; i++)
{
uint32_t val;
uint32_t w1, w2, w3;
w1 = words_map.at(wlist[i*3]);
w2 = words_map.at(wlist[i*3 + 1]);
w3 = words_map.at(wlist[i*3 + 2]);
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val = w1 + n * (((n - w1) + w2) % n) + n * n * (((n - w2) + w3) % n);
if (!(val % n == w1)) return false;
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memcpy(dst.data + i * 4, &val, 4); // copy 4 bytes to position
}
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std::string wlist_copy = words;
if (wlist.size() == 12)
{
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memcpy(dst.data, dst.data + 16, 16); // if electrum 12-word seed, duplicate
wlist_copy += ' ';
wlist_copy += words;
}
return true;
}
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/*!
* \brief Converts bytes (secret key) to seed words.
* \param src Secret key
* \param words Space separated words get copied here.
* \return Whether it was successful or not. Unsuccessful if wrong key size.
*/
bool bytes_to_words(const crypto::secret_key& src, std::string& words)
{
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if (is_uninitialized())
{
init("", true);
}
int n = num_words;
if (sizeof(src.data) % 4 != 0) return false;
// 8 bytes -> 3 words. 8 digits base 16 -> 3 digits base 1626
for (unsigned int i=0; i < sizeof(src.data)/4; i++, words += ' ')
{
uint32_t w1, w2, w3;
uint32_t val;
memcpy(&val, (src.data) + (i * 4), 4);
w1 = val % n;
w2 = ((val / n) + w1) % n;
w3 = (((val / n) / n) + w2) % n;
words += words_array[w1];
words += ' ';
words += words_array[w2];
words += ' ';
words += words_array[w3];
}
return false;
}
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/*!
* \brief Gets a list of seed languages that are supported.
* \param languages The list gets added to this.
*/
void get_language_list(std::vector<std::string> &languages)
{
languages.clear();
boost::filesystem::path languages_directory("wordlists/languages");
if (!boost::filesystem::exists(languages_directory) ||
!boost::filesystem::is_directory(languages_directory))
{
throw std::runtime_error("Word list languages directory is missing.");
}
boost::filesystem::directory_iterator end;
for (boost::filesystem::directory_iterator it(languages_directory); it != end; it++)
{
languages.push_back(it->path().filename().string());
}
}
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}
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}