text: // Copyright (c) 2014-2018, The Monero Project
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  /*!
   * \file electrum-words.h
   * 
   * \brief Mnemonic seed generation and wallet restoration from them.
   * 
   * This file and its cpp 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.
   */
  
  #ifndef ELECTRUM_WORDS_H
  #define ELECTRUM_WORDS_H
  
  #include <string>
  #include <cstdint>
  #include <map>
  #include "crypto/crypto.h"  // for declaration of crypto::secret_key
  
  /*!
   * \namespace crypto
   * 
   * \brief crypto namespace.
   */
  namespace crypto
  {
    /*!
     * \namespace crypto::electrum_words
     * 
     * \brief Mnemonic seed word generation and wallet restoration helper functions.
     */
    namespace electrum_words
    {
  
      const int seed_length = 24;
      const std::string old_language_name = "EnglishOld";
      /*!
       * \brief Converts seed words to bytes (secret key).
       * \param  words           String containing the words separated by spaces.
       * \param  dst             To put the secret data restored from the words.
       * \param  len             The number of bytes to expect, 0 if unknown
       * \param  duplicate       If true and len is not zero, we accept half the data, and duplicate it
       * \param  language_name   seed_language of the seed as found gets written here.
       * \return                 false if not a multiple of 3 words, or if word is not in the words list
       */
      bool words_to_bytes(std::string words, std::string& dst, size_t len, bool duplicate,
        std::string &language_name);
      /*!
       * \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.
       * \param  language_name   seed_language of the seed as found gets written here.
       * \return                 false if not a multiple of 3 words, or if word is not in the words list
       */
      bool words_to_bytes(std::string words, crypto::SecretKey& dst,
        std::string &language_name);
  
      /*!
       * \brief Converts bytes to seed words.
       * \param  src           Secret data
       * \param  len           Secret data length in bytes (positive multiples of 4 only)
       * \param  words         Space delimited concatenated words get written here.
       * \param  language_name Seed language name
       * \return               true if successful false if not. Unsuccessful if wrong key size.
       */
      bool bytes_to_words(const char *src, size_t len, std::string& words,
        const std::string &language_name);
  
      /*!
       * \brief Converts bytes (secret key) to seed words.
       * \param  src           Secret key
       * \param  words         Space delimited concatenated words get written here.
       * \param  language_name Seed language name
       * \return               true if successful false if not. Unsuccessful if wrong key size.
       */
      bool bytes_to_words(const crypto::SecretKey& src, std::string& words,
        const std::string &language_name);
  
      /*!
       * \brief Gets a list of seed languages that are supported.
       * \param languages A vector is set to the list of languages.
       */
      void get_language_list(std::vector<std::string> &languages);
  
      /*!
       * \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(std::string seed);
    }
  }
  
  #endif
  