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       1              : // Copyright (c) 2017, 2021 Pieter Wuille
       2              : // Copyright (c) 2021 The Bitcoin Core developers
       3              : // Distributed under the MIT software license, see the accompanying
       4              : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       5              : 
       6              : // Bech32 and Bech32m are string encoding formats used in newer
       7              : // address types. The outputs consist of a human-readable part
       8              : // (alphanumeric), a separator character (1), and a base32 data
       9              : // section, the last 6 characters of which are a checksum. The
      10              : // module is namespaced under bech32 for historical reasons.
      11              : //
      12              : // For more information, see BIP 173 and BIP 350.
      13              : 
      14              : #ifndef BITCOIN_BECH32_H
      15              : #define BITCOIN_BECH32_H
      16              : 
      17              : #include <stdint.h>
      18              : #include <string>
      19              : #include <vector>
      20              : 
      21              : namespace bech32
      22              : {
      23              : 
      24              : /** The Bech32 and Bech32m checksum size */
      25              : constexpr size_t CHECKSUM_SIZE = 6;
      26              : 
      27              : enum class Encoding {
      28              :     INVALID, //!< Failed decoding
      29              : 
      30              :     BECH32,  //!< Bech32 encoding as defined in BIP173
      31              :     BECH32M, //!< Bech32m encoding as defined in BIP350
      32              : };
      33              : 
      34              : /** Character limits for Bech32(m) encoded strings. Character limits are how we provide error location guarantees.
      35              :  *  These values should never exceed 2^31 - 1 (max value for a 32-bit int), since there are places where we may need to
      36              :  *  convert the CharLimit::VALUE to an int. In practice, this should never happen since this CharLimit applies to an address encoding
      37              :  *  and we would never encode an address with such a massive value */
      38              : enum CharLimit : size_t {
      39              :     BECH32 = 90,            //!< BIP173/350 imposed character limit for Bech32(m) encoded addresses. This guarantees finding up to 4 errors.
      40              : };
      41              : 
      42              : /** Encode a Bech32 or Bech32m string. If hrp contains uppercase characters, this will cause an
      43              :  *  assertion error. Encoding must be one of BECH32 or BECH32M. */
      44              : std::string Encode(Encoding encoding, const std::string& hrp, const std::vector<uint8_t>& values);
      45              : 
      46        14252 : struct DecodeResult
      47              : {
      48              :     Encoding encoding;         //!< What encoding was detected in the result; Encoding::INVALID if failed.
      49              :     std::string hrp;           //!< The human readable part
      50              :     std::vector<uint8_t> data; //!< The payload (excluding checksum)
      51              : 
      52           53 :     DecodeResult() : encoding(Encoding::INVALID) {}
      53        14199 :     DecodeResult(Encoding enc, std::string&& h, std::vector<uint8_t>&& d) : encoding(enc), hrp(std::move(h)), data(std::move(d)) {}
      54              : };
      55              : 
      56              : /** Decode a Bech32 or Bech32m string. */
      57              : DecodeResult Decode(const std::string& str, CharLimit limit = CharLimit::BECH32);
      58              : 
      59              : /** Return the positions of errors in a Bech32 string. */
      60              : std::pair<std::string, std::vector<int>> LocateErrors(const std::string& str, CharLimit limit = CharLimit::BECH32);
      61              : 
      62              : } // namespace bech32
      63              : 
      64              : #endif // BITCOIN_BECH32_H