第七节 Merkle树

2!=0）

merkle.push_back（merkle.back（））;

//List size is now even.

assert（merkle.size（）% 2==0）;

//New hash list.

bc::hash_digest_list new_merkle;

//Loop through hashes 2 atatime.

for（auto it=merkle.begin（）;it!=merkle.end（）;it+=2）{

//Join both current hashes together（concatenate）.

bc::data_chunk concat_data（bc::hash_size*2）;

auto concat=bc::make_serializer（concat_data.begin（））;

concat.write_hash（*it）;

concat.write_hash（*（it+1））;

assert（concat.iterator（）==concat_data.end（））;

//Hash both of the hashes.

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

//Add this to the new list.

new_merkle.push_back（new_root）;

//This is the new list.

merkle=new_merkle;

//DEBUG output------------------------------------

std::cout<<"Current merkle hash list:"<

for（const auto&hash:merkle）

std::cout<<""<

std::cout<

//-------------------------------------------------

//Finally we end up withasingle item.

return merkle[0];

int main（）{

//Replace these hashes with ones fromablock to reproduce the same merkle root.

bc::hash_digest_list tx_hashes{

bc::decode_hash（"0000000000000000000000000000000000000000000000000000000000000000"），

bc::decode_hash（"0000000000000000000000000000000000000000000000000000000000000011"），

bc::decode_hash（"0000000000000000000000000000000000000000000000000000000000000022"），

};

const bc::hash_digest merkle_root=create_merkle（tx_hashes）;

std::cout<<"Result:"<

return 0;

例2展示了编译以及运行上述代码后的结果。

例2 编译以及运行构造Merkle树代码。

$#Compile the merkle.cpp code

$g++-o merkle merkle.cpp$（pkg-config--cflags--libs libbitcoin）

$#Run the merkle executable

$./merkle

Current merkle hash list:

32650049a0418e4380db0af81788635d8b65424d397170b8499cdc28c4d27006

30861db96905c8dc8b99398ca1cd5bd5b84ac3264a4e1b3e65afa1bcee7540c4

Current merkle hash list:

d47780c084bad3830bcdaf6eace035e4c6cbf646d103795d22104fb105014ba3

Result:d47780c084bad3830bcdaf6eace035e4c6cbf646d103795d22104fb105014ba3

Merkle树的高效率随