1 // Copyright (c) 2017, 2021 Pieter Wuille
2 // Copyright (c) 2021-present 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 <cstddef>
18 #include <cstdint>
19 #include <string>
20 #include <utility>
21 #include <vector>
22 23 namespace bech32
24 {
25 26 static constexpr size_t CHECKSUM_SIZE = 6;
27 static constexpr char SEPARATOR = '1';
28 29 enum class Encoding {
30 INVALID, //!< Failed decoding
31 32 BECH32, //!< Bech32 encoding as defined in BIP173
33 BECH32M, //!< Bech32m encoding as defined in BIP350
34 };
35 36 /** Character limits for Bech32(m) encoded strings. Character limits are how we provide error location guarantees.
37 * These values should never exceed 2^31 - 1 (max value for a 32-bit int), since there are places where we may need to
38 * convert the CharLimit::VALUE to an int. In practice, this should never happen since this CharLimit applies to an address encoding
39 * and we would never encode an address with such a massive value */
40 enum CharLimit : size_t {
41 BECH32 = 90, //!< BIP173/350 imposed character limit for Bech32(m) encoded addresses. This guarantees finding up to 4 errors.
42 };
43 44 /** Encode a Bech32 or Bech32m string. If hrp contains uppercase characters, this will cause an
45 * assertion error. Encoding must be one of BECH32 or BECH32M. */
46 std::string Encode(Encoding encoding, const std::string& hrp, const std::vector<uint8_t>& values);
47 48 struct DecodeResult
49 {
50 Encoding encoding; //!< What encoding was detected in the result; Encoding::INVALID if failed.
51 std::string hrp; //!< The human readable part
52 std::vector<uint8_t> data; //!< The payload (excluding checksum)
53 54 DecodeResult() : encoding(Encoding::INVALID) {}
55 DecodeResult(Encoding enc, std::string&& h, std::vector<uint8_t>&& d) : encoding(enc), hrp(std::move(h)), data(std::move(d)) {}
56 };
57 58 /** Decode a Bech32 or Bech32m string. */
59 DecodeResult Decode(const std::string& str, CharLimit limit = CharLimit::BECH32);
60 61 /** Return the positions of errors in a Bech32 string. */
62 std::pair<std::string, std::vector<int>> LocateErrors(const std::string& str, CharLimit limit = CharLimit::BECH32);
63 64 } // namespace bech32
65 66 #endif // BITCOIN_BECH32_H
67