Computing Merkle Tree: Example in C++.

gistfile1.txt

#include <QCoreApplication>
#include <QDebug>

#include <QByteArray>
#include <QCryptographicHash>

QByteArray sha256(QByteArray in)
{
    QCryptographicHash hash (QCryptographicHash::Sha256);

    hash.addData(in);

    QByteArray res1 = hash.result();

    return res1;
}

QByteArray sha256d(QByteArray in)
{
    QCryptographicHash hash (QCryptographicHash::Sha256);

    hash.addData(in);

    QByteArray res1 = hash.result();
    hash.reset();
    hash.addData(res1);

    return hash.result();
}

QByteArray reverse_hash (QByteArray in)
{
    QByteArray res;
    if (in.length() != 32) return QByteArray::fromHex("");

    for (int i = 0; i < 32; ++i)
    {
        res.append(in[31 - i]);
    }

    return res;
}

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    {//BTC block 70003
    QByteArray a = QByteArray::fromHex("6a7df1c030c1ad32cbaa21aa491194ac3b945f0dbe61dff2ef95f9c62f5650ee");
    QByteArray b = QByteArray::fromHex("8e32e4a5ba602390a1e9cc019bd3a49a68e2116a56310e12c5bbeab142a67720");
    a = reverse_hash(a);
    b = reverse_hash(b);

    QByteArray c = a + b;
    QByteArray m = sha256d( c );
    m = reverse_hash(m);

    qDebug() << m.toHex();
    }


    {//VTC block 800019
    QByteArray a = QByteArray::fromHex("32e60eb21632597c1c1545c63fae57df8d4455648b7d97150b7dcee706749588");
    QByteArray b = QByteArray::fromHex("1deed158ada568b9b193473095c8eb2cef2cffe60ccce15c3c82f599a09767a8");
    a = reverse_hash(a);
    b = reverse_hash(b);

    qDebug() << a.toHex();
    qDebug() << b.toHex();

    QByteArray c = a + b;
    QByteArray m = sha256d( c );
    m = reverse_hash(m);

    qDebug() << m.toHex();
    }


    return 0;
}