base58.cpp
1 // Copyright (c) 2014-present The Bitcoin Core developers 2 // Distributed under the MIT software license, see the accompanying 3 // file COPYING or http://www.opensource.org/licenses/mit-license.php. 4 5 #include <base58.h> 6 7 #include <hash.h> 8 #include <uint256.h> 9 #include <util/strencodings.h> 10 #include <util/string.h> 11 12 #include <cassert> 13 #include <cstring> 14 15 #include <limits> 16 17 using util::ContainsNoNUL; 18 19 /** All alphanumeric characters except for "0", "I", "O", and "l" */ 20 static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"; 21 static const int8_t mapBase58[256] = { 22 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 23 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 24 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 25 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8,-1,-1,-1,-1,-1,-1, 26 -1, 9,10,11,12,13,14,15, 16,-1,17,18,19,20,21,-1, 27 22,23,24,25,26,27,28,29, 30,31,32,-1,-1,-1,-1,-1, 28 -1,33,34,35,36,37,38,39, 40,41,42,43,-1,44,45,46, 29 47,48,49,50,51,52,53,54, 55,56,57,-1,-1,-1,-1,-1, 30 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 31 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 32 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 33 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 34 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 35 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 36 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 37 -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, 38 }; 39 40 [[nodiscard]] static bool DecodeBase58(const char* psz, std::vector<unsigned char>& vch, int max_ret_len) 41 { 42 // Skip leading spaces. 43 while (*psz && IsSpace(*psz)) 44 psz++; 45 // Skip and count leading '1's. 46 int zeroes = 0; 47 int length = 0; 48 while (*psz == '1') { 49 zeroes++; 50 if (zeroes > max_ret_len) return false; 51 psz++; 52 } 53 // Allocate enough space in big-endian base256 representation. 54 int size = strlen(psz) * 733 /1000 + 1; // log(58) / log(256), rounded up. 55 std::vector<unsigned char> b256(size); 56 // Process the characters. 57 static_assert(std::size(mapBase58) == 256, "mapBase58.size() should be 256"); // guarantee not out of range 58 while (*psz && !IsSpace(*psz)) { 59 // Decode base58 character 60 int carry = mapBase58[(uint8_t)*psz]; 61 if (carry == -1) // Invalid b58 character 62 return false; 63 int i = 0; 64 for (std::vector<unsigned char>::reverse_iterator it = b256.rbegin(); (carry != 0 || i < length) && (it != b256.rend()); ++it, ++i) { 65 carry += 58 * (*it); 66 *it = carry % 256; 67 carry /= 256; 68 } 69 assert(carry == 0); 70 length = i; 71 if (length + zeroes > max_ret_len) return false; 72 psz++; 73 } 74 // Skip trailing spaces. 75 while (IsSpace(*psz)) 76 psz++; 77 if (*psz != 0) 78 return false; 79 // Skip leading zeroes in b256. 80 std::vector<unsigned char>::iterator it = b256.begin() + (size - length); 81 // Copy result into output vector. 82 vch.reserve(zeroes + (b256.end() - it)); 83 vch.assign(zeroes, 0x00); 84 while (it != b256.end()) 85 vch.push_back(*(it++)); 86 return true; 87 } 88 89 std::string EncodeBase58(std::span<const unsigned char> input) 90 { 91 // Skip & count leading zeroes. 92 int zeroes = 0; 93 int length = 0; 94 while (input.size() > 0 && input[0] == 0) { 95 input = input.subspan(1); 96 zeroes++; 97 } 98 // Allocate enough space in big-endian base58 representation. 99 int size = input.size() * 138 / 100 + 1; // log(256) / log(58), rounded up. 100 std::vector<unsigned char> b58(size); 101 // Process the bytes. 102 while (input.size() > 0) { 103 int carry = input[0]; 104 int i = 0; 105 // Apply "b58 = b58 * 256 + ch". 106 for (std::vector<unsigned char>::reverse_iterator it = b58.rbegin(); (carry != 0 || i < length) && (it != b58.rend()); it++, i++) { 107 carry += 256 * (*it); 108 *it = carry % 58; 109 carry /= 58; 110 } 111 112 assert(carry == 0); 113 length = i; 114 input = input.subspan(1); 115 } 116 // Skip leading zeroes in base58 result. 117 std::vector<unsigned char>::iterator it = b58.begin() + (size - length); 118 while (it != b58.end() && *it == 0) 119 it++; 120 // Translate the result into a string. 121 std::string str; 122 str.reserve(zeroes + (b58.end() - it)); 123 str.assign(zeroes, '1'); 124 while (it != b58.end()) 125 str += pszBase58[*(it++)]; 126 return str; 127 } 128 129 bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret_len) 130 { 131 if (!ContainsNoNUL(str)) { 132 return false; 133 } 134 return DecodeBase58(str.c_str(), vchRet, max_ret_len); 135 } 136 137 std::string EncodeBase58Check(std::span<const unsigned char> input) 138 { 139 // add 4-byte hash check to the end 140 std::vector<unsigned char> vch(input.begin(), input.end()); 141 uint256 hash = Hash(vch); 142 vch.insert(vch.end(), hash.data(), hash.data() + 4); 143 return EncodeBase58(vch); 144 } 145 146 [[nodiscard]] static bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet, int max_ret_len) 147 { 148 if (!DecodeBase58(psz, vchRet, max_ret_len > std::numeric_limits<int>::max() - 4 ? std::numeric_limits<int>::max() : max_ret_len + 4) || 149 (vchRet.size() < 4)) { 150 vchRet.clear(); 151 return false; 152 } 153 // re-calculate the checksum, ensure it matches the included 4-byte checksum 154 uint256 hash = Hash(std::span{vchRet}.first(vchRet.size() - 4)); 155 if (memcmp(&hash, &vchRet[vchRet.size() - 4], 4) != 0) { 156 vchRet.clear(); 157 return false; 158 } 159 vchRet.resize(vchRet.size() - 4); 160 return true; 161 } 162 163 bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret) 164 { 165 if (!ContainsNoNUL(str)) { 166 return false; 167 } 168 return DecodeBase58Check(str.c_str(), vchRet, max_ret); 169 }