// Copyright (c) 2014, The Monero Project
//
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// 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
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/*
* 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>
#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>
#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;
const std::string WORD_LISTS_DIRECTORY = "wordlists";
const std::string LANGUAGES_DIRECTORY = "languages";
const std::string OLD_WORD_FILE = "old-word-list";
bool is_uninitialized()
{
return num_words == 0 ? true : false;
}
void create_data_structures(const std::string &word_file)
{
words_array.clear();
words_map.clear();
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();
}
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;
}
}
namespace crypto
{
namespace ElectrumWords
{
void init(const std::string &language, bool old_word_list)
{
if (old_word_list)
{
create_data_structures(WORD_LISTS_DIRECTORY + '/' + OLD_WORD_FILE);
}
else
{
create_data_structures(WORD_LISTS_DIRECTORY + '/' + LANGUAGES_DIRECTORY + '/' + language);
}
if (num_words == 0)
{
throw std::runtime_error(std::string("Word list file is corrupt: ") +
old_word_list ? OLD_WORD_FILE : (LANGUAGES_DIRECTORY + '/' + language));
}
}
/* convert words to bytes, 3 words -> 4 bytes
* returns:
* false if not a multiple of 3 words, or if a words is not in the
* words list
*
* true otherwise
*/
bool words_to_bytes(const std::string& words, crypto::secret_key& dst)
{
std::vector<std::string> wlist;
boost::split(wlist, words, boost::is_any_of(" "));
std::vector<std::string> languages;
std::vector<std::string>::iterator it;
get_language_list(languages);
for (it = languages.begin(); it != languages.end() &&
!word_list_file_match(wlist); it++)
{
init(*it);
}
if (it == languages.end())
{
init("", true);
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]);
val = w1 + n * (((n - w1) + w2) % n) + n * n * (((n - w2) + w3) % n);
if (!(val % n == w1)) return false;
memcpy(dst.data + i * 4, &val, 4); // copy 4 bytes to position
}
std::string wlist_copy = words;
if (wlist.size() == 12)
{
memcpy(dst.data, dst.data + 16, 16); // if electrum 12-word seed, duplicate
wlist_copy += ' ';
wlist_copy += words;
}
return true;
}
/* convert bytes to words, 4 bytes-> 3 words
* returns:
* false if wrong number of bytes (shouldn't be possible)
* true otherwise
*/
bool bytes_to_words(const crypto::secret_key& src, std::string& words)
{
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;
}
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());
}
}
} // namespace ElectrumWords
} // namespace crypto
