Bitcoin/address validation: Difference between revisions
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}
</syntaxhighlight>
=={{header|C++}}==
This example uses the C++ code from the SHA-256 task. This slightly complicates the code because the previous task
was designed to hash a string of ASCII characters rather than a byte array.
<syntaxhighlight lang="c++">
#include <algorithm>
#include <cstdint>
#include <iostream>
#include <map>
#include <stdexcept>
#include <string>
#include <vector>
#include "SHA256.cpp"
SHA256 sha256{ };
const std::string ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
std::map<char, int32_t> base_map =
{ { '0', 0 }, { '1', 1 }, { '2', 2 }, { '3', 3 }, { '4', 4 }, { '5', 5 }, { '6', 6 }, { '7', 7 },
{ '8', 8 }, { '9', 9 }, { 'a', 10 }, { 'b', 11 }, { 'c', 12 }, { 'd', 13 }, { 'e', 14 }, { 'f', 15 } };
std::vector<int32_t> hex_to_bytes(const std::string& text) {
std::vector<int32_t> bytes(text.size() / 2, 0);
for ( uint64_t i = 0; i < text.size(); i += 2 ) {
const int32_t first_digit = base_map[text[i]];
const int32_t second_digit = base_map[text[i + 1]];
bytes[i / 2] = ( ( first_digit << 4 ) + second_digit );;
}
return bytes;
}
std::string vector_to_ascii_string(const std::vector<int32_t>& bytes) {
std::string result = "";
for ( uint32_t i = 0; i < bytes.size(); ++i ) {
result += static_cast<char>(bytes[i]);
}
return result;
}
std::vector<int32_t> decode_base_58(const std::string& text) {
std::vector<int32_t> result(25, 0);
for ( const char& ch : text ) {
std::string::size_type index = ALPHABET.find(ch);
if ( index == static_cast<uint64_t>(-1) ) {
throw std::invalid_argument("Invalid character found in bitcoin address: " + ch);
}
for ( uint64_t i = result.size() - 1; i > 0; i-- ) {
index += 58 * result[i];
result[i] = index & 0xFF;
index >>= 8;
}
if ( index != 0 ) {
throw std::invalid_argument("Bitcoin address is too long");
}
}
return result;
}
bool is_valid(const std::string& address) {
if ( address.size() < 26 || address.size() > 35 ) {
throw std::invalid_argument("Invalid length of bitcoin address");
}
std::vector<int32_t> decoded = decode_base_58(address);
std::vector first21(decoded.begin(), decoded.begin() + 21);
// Convert the 'first21' into a suitable ASCII string for the first SHA256 hash
std::string text = vector_to_ascii_string(first21);
std::string hash_1 = sha256.message_digest(text);
// Convert 'hashOne' into a suitable ASCII string for the second SHA256 hash
std::vector<int32_t> bytes_1 = hex_to_bytes(hash_1);
std::string ascii_1 = vector_to_ascii_string(bytes_1);
std::string hash_2 = sha256.message_digest(ascii_1);
std::vector<int32_t> bytes_2 = hex_to_bytes(hash_2);
std::vector<int32_t> checksum(bytes_2.begin(), bytes_2.begin() + 4);
std::vector<int32_t> last4(decoded.begin() + 21, decoded.begin() + 25);
return checksum == last4;
}
int main() {
const std::vector<std::string> addresses = { "1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62i",
"1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62j",
"1Q1pE5vPGEEMqRcVRMbtBK842Y6Pzo6nK9",
"1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62X",
"1ANNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62i" };
for ( const std::string& address : addresses ) {
std::cout << address << " : " << std::boolalpha << is_valid(address) << std::endl;
}
}
</syntaxhighlight>
{{ out }}
<pre>
1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62i : true
1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62j : false
1Q1pE5vPGEEMqRcVRMbtBK842Y6Pzo6nK9 : true
1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62X : false
1ANNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62i : false
</pre>
=={{header|D}}==
This requires the D module from the SHA-256 Task.
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