// Copyright (c) 2014, The Monero Project
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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>
#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>
#include <boost/crc.hpp>
#include <boost/algorithm/string/join.hpp>
namespace
{
int num_words = 0;
const int seed_length = 24;
std::map<std::string,uint32_t> words_map;
std::vector<std::string> words_array;
bool is_old_style_word_list = false;
const std::string WORD_LISTS_DIRECTORY = "wordlists";
const std::string LANGUAGES_DIRECTORY = "languages";
const std::string OLD_WORD_FILE = "old-word-list";
const int unique_prefix_length = 4;
/*!
* \brief Tells if the module hasn't been initialized with a word list file.
* \return true if the module hasn't been initialized with a word list file false otherwise.
*/
bool is_uninitialized()
{
return num_words == 0 ? true : false;
}
/*!
* \brief 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.
* \param has_checksum True if checksum was supplied false if not.
*/
void create_data_structures(const std::string &word_file, bool has_checksum)
{
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("Word list file couldn't be opened.");
std::string word;
while (input_stream >> word)
{
words_array.push_back(word);
if (has_checksum)
{
// Only if checksum was passed should we stick to just 4 char checks to be lenient about typos.
words_map[word.substr(0, unique_prefix_length)] = num_words;
}
else
{
words_map[word] = num_words;
}
num_words++;
}
input_stream.close();
}
/*!
* \brief Tells if all the words passed in wlist was present in current word list file.
* \param wlist List of words to match.
* \param has_checksum If word list passed checksum test, we need to only do a 4 char check.
* \return true if all the words were present false if not.
*/
bool word_list_file_match(const std::vector<std::string> &wlist, bool has_checksum)
{
for (std::vector<std::string>::const_iterator it = wlist.begin(); it != wlist.end(); it++)
{
if (has_checksum)
{
if (words_map.count(it->substr(0, unique_prefix_length)) == 0)
{
return false;
}
}
else
{
if (words_map.count(*it) == 0)
{
return false;
}
}
}
return true;
}
/*!
* \brief Creates a checksum index in the word list array on the list of words.
* \param word_list Vector of words
* \return Checksum index
*/
uint32_t create_checksum_index(const std::vector<std::string> &word_list)
{
std::string four_char_words = "";
for (std::vector<std::string>::const_iterator it = word_list.begin(); it != word_list.end(); it++)
{
four_char_words += it->substr(0, unique_prefix_length);
}
boost::crc_32_type result;
result.process_bytes(four_char_words.data(), four_char_words.length());
return result.checksum() % seed_length;
}
}
/*!
* \namespace crypto
*
* \brief crypto namespace.
*/
namespace crypto
{
/*!
* \namespace crypto::ElectrumWords
*
* \brief Mnemonic seed word generation and wallet restoration helper functions.
*/
namespace ElectrumWords
{
/*!
* \brief Called to initialize it to work with a word list file.
* \param language Language of the word list file.
* \param has_checksum True if the checksum was passed false if not.
* \param old_word_list true it is to use the old style word list file false if not.
*/
void init(const std::string &language, bool has_checksum, bool old_word_list)
{
if (old_word_list)
{
// Use the old word list file if told to.
create_data_structures(WORD_LISTS_DIRECTORY + '/' + OLD_WORD_FILE, has_checksum);
is_old_style_word_list = true;
}
else
{
create_data_structures(WORD_LISTS_DIRECTORY + '/' + LANGUAGES_DIRECTORY + '/' + language, has_checksum);
is_old_style_word_list = false;
}
if (num_words == 0)
{
throw std::runtime_error(std::string("Word list file is empty: ") +
(old_word_list ? OLD_WORD_FILE : (LANGUAGES_DIRECTORY + '/' + language)));
}
}
/*!
* \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)
{
std::vector<std::string> wlist;
boost::split(wlist, words, boost::is_any_of(" "));
// If it is seed with a checksum.
bool has_checksum = (wlist.size() == seed_length + 1);
if (has_checksum)
{
// The last word is the checksum.
std::string last_word = wlist.back();
wlist.pop_back();
std::string checksum = wlist[create_checksum_index(wlist)];
if (checksum.substr(0, unique_prefix_length) != last_word.substr(0, unique_prefix_length))
{
// Checksum fail
return false;
}
}
// Try to find a word list file that contains all the words in the word list.
std::vector<std::string> languages;
get_language_list(languages);
std::vector<std::string>::iterator it;
for (it = languages.begin(); it != languages.end(); it++)
{
init(*it, has_checksum);
if (word_list_file_match(wlist, has_checksum))
{
break;
}
}
// If no such file was found, see if the old style word list file has them all.
if (it == languages.end())
{
init("", has_checksum, true);
if (!word_list_file_match(wlist, has_checksum))
{
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;
if (has_checksum)
{
w1 = words_map.at(wlist[i*3].substr(0, unique_prefix_length));
w2 = words_map.at(wlist[i*3 + 1].substr(0, unique_prefix_length));
w3 = words_map.at(wlist[i*3 + 2].substr(0, unique_prefix_length));
}
else
{
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;
}
/*!
* \brief Converts bytes (secret key) to seed words.
* \param src Secret key
* \param words Space delimited concatenated words get written here.
* \return true if successful false if not. Unsuccessful if wrong key size.
*/
bool bytes_to_words(const crypto::secret_key& src, std::string& words)
{
if (is_uninitialized())
{
init("english", true);
}
// To store the words for random access to add the checksum word later.
std::vector<std::string> words_store;
int n = num_words;
if (sizeof(src.data) % 4 != 0 || sizeof(src.data) == 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];
words_store.push_back(words_array[w1]);
words_store.push_back(words_array[w2]);
words_store.push_back(words_array[w3]);
}
words.pop_back();
words += (' ' + words_store[create_checksum_index(words_store)]);
return false;
}
/*!
* \brief Gets a list of seed languages that are supported.
* \param languages The vector is set to the list of languages.
*/
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());
}
}
/*!
* \brief Tells if the module is currenly using an old style word list.
* \return true if it is currenly using an old style word list false if not.
*/
bool get_is_old_style_word_list()
{
if (is_uninitialized())
{
throw std::runtime_error("ElectrumWords hasn't been initialized with a word list yet.");
}
return is_old_style_word_list;
}
/*!
* \brief Tells if the seed passed is an old style seed or not.
* \param seed The seed to check (a space delimited concatenated word list)
* \return true if the seed passed is a old style seed false if not.
*/
bool get_is_old_style_seed(const std::string &seed)
{
std::vector<std::string> wlist;
boost::split(wlist, seed, boost::is_any_of(" "));
return wlist.size() != (seed_length + 1);
}
}
}