Merkle tree

• merkle tree中文文档
• 英文文档

#include <cstdlib>
#include <string>
#include <bitcoin/bitcoin.hpp>

BC_USE_LIBBITCOIN_MAIN

using namespace bc;

bc::hash_digest calculate_merkle_root(bc::hash_list &merkle);

int bc::main(int argc, char *argv[])
{
    bc::cout << "测试 merkle_tree" << std::endl;

    bc::hash_list tx_hashes{
        bc::hash_literal("0000000000000000000000000000000000000000000000000000000000000000"),
        bc::hash_literal("0000000000000000000000000000000000000000000000000000000000000011"),
        bc::hash_literal("0000000000000000000000000000000000000000000000000000000000000022"),
    };

    bc::hash_digest merkle_root = calculate_merkle_root(tx_hashes);

    bc::string right_hash = "d47780c084bad3830bcdaf6eace035e4c6cbf646d103795d22104fb105014ba3";
    assert(right_hash == bc::encode_hash(merkle_root));

    bc::cout << bc::encode_hash(merkle_root) << std::endl;

    return 0;
}

/**
 * 计算 merkle root
 */
bc::hash_digest calculate_merkle_root(bc::hash_list &merkle)
{
    if (merkle.empty())
    {
        return bc::null_hash;
    }

    if (merkle.size() == 1)
    {
        return merkle[0];
    }

    // 如果不是偶数, 则将最后一个元素复制一份凑成偶数
    if (0 != (merkle.size() & 1))
    {
        merkle.push_back(merkle.back());
    }
    assert(0 == (merkle.size() & 1));

    bc::hash_list tmp_merkle;
    for (auto it = merkle.begin(); it != merkle.end(); it += 2)
    {
        bc::data_chunk concat_data(bc::hash_size * 2);
        auto concat = bc::make_unsafe_serializer(concat_data.begin());
        concat.write_hash(*it);
        concat.write_hash(*(it + 1));
        //assert(concat.  == concat_data.end());

        bc::hash_digest new_root = bc::bitcoin_hash(concat_data);

        tmp_merkle.push_back(new_root);
    }

    merkle = tmp_merkle;          //size 变为原来的一半
    return calculate_merkle_root(merkle); //继续递归, 当然可以用迭代代替
}