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https://github.com/bitcoinbook/bitcoinbook
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63 lines
2.3 KiB
C++
63 lines
2.3 KiB
C++
#include <bitcoin/bitcoin.hpp>
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bc::hash_digest create_merkle(bc::hash_digest_list& merkle)
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{
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// Stop if hash list is empty.
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if (merkle.empty())
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return bc::null_hash;
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else if (merkle.size() == 1)
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return merkle[0];
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// While there is more than 1 hash in the list, keep looping...
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while (merkle.size() > 1)
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{
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// If number of hashes is odd, duplicate last hash in the list.
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if (merkle.size() % 2 != 0)
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merkle.push_back(merkle.back());
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// List size is now even.
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assert(merkle.size() % 2 == 0);
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// New hash list.
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bc::hash_digest_list new_merkle;
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// Loop through hashes 2 at a time.
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for (auto it = merkle.begin(); it != merkle.end(); it += 2)
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{
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// Join both current hashes together (concatenate).
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bc::data_chunk concat_data(bc::hash_size * 2);
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auto concat = bc::make_serializer(concat_data.begin());
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concat.write_hash(*it);
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concat.write_hash(*(it + 1));
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assert(concat.iterator() == concat_data.end());
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// Hash both of the hashes.
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bc::hash_digest new_root = bc::bitcoin_hash(concat_data);
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// Add this to the new list.
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new_merkle.push_back(new_root);
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}
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// This is the new list.
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merkle = new_merkle;
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// DEBUG output -------------------------------------
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std::cout << "Current merkle hash list:" << std::endl;
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for (const auto& hash: merkle)
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std::cout << " " << bc::encode_hex(hash) << std::endl;
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std::cout << std::endl;
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// --------------------------------------------------
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}
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// Finally we end up with a single item.
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return merkle[0];
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}
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int main()
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{
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// Replace these hashes with ones from a block to reproduce the same merkle root.
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bc::hash_digest_list tx_hashes{{
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bc::decode_hash("0000000000000000000000000000000000000000000000000000000000000000"),
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bc::decode_hash("0000000000000000000000000000000000000000000000000000000000000011"),
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bc::decode_hash("0000000000000000000000000000000000000000000000000000000000000022"),
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}};
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const bc::hash_digest merkle_root = create_merkle(tx_hashes);
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std::cout << "Result: " << bc::encode_hex(merkle_root) << std::endl;
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return 0;
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}
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