hash_digest build_merkle_tree(hash_list& merkle)
{
if (merkle.empty())
return null_hash;
else if (merkle.size() == 1)
return merkle[0];
while (merkle.size() > 1)
{
if (merkle.size() % 2 != 0)
merkle.push_back(merkle.back());
hash_list new_merkle;
for (auto it = merkle.begin(); it != merkle.end(); it += 2)
{
serializer concat;
concat.write_hash(*it);
concat.write_hash(*(it + 1));
hash_digest new_root = generate_sha256_hash(concat.data());
new_merkle.push_back(new_root);
}
merkle = new_merkle;
}
return merkle[0];
}
hash_digest build_merkle_tree(hash_list& merkle)
{
// Stop if hash list is empty.
if (merkle.empty())
return null_hash;
// While there is more than 1 hash in the list, keep looping...
while (merkle.size() > 1)
{
// If number of hashes is odd, duplicate last hash in the list.
if (merkle.size() % 2 != 0)
merkle.push_back(merkle.back());
// List size is now even.
BITCOIN_ASSERT(merkle.size() % 2 == 0);
// New hash list.
hash_list new_merkle;
// Loop through hashes 2 at a time.
for (auto it = merkle.begin(); it != merkle.end(); it += 2)
{
// Join both current hashes together (concatenate).
data_chunk concat_data;
data_sink concat_stream(concat_data);
ostream_writer concat_sink(concat_stream);
concat_sink.write_hash(*it);
concat_sink.write_hash(*(it + 1));
concat_stream.flush();
BITCOIN_ASSERT(concat_data.size() == (2 * hash_size));
// Hash both of the hashes.
const auto new_root = bitcoin_hash(concat_data);
// Add this to the new list.
new_merkle.push_back(new_root);
}
// This is the new list.
merkle = new_merkle;
}
// Finally we end up with a single item.
return merkle[0];
}