uint256 ProofOfWork::solve (int maxIterations) const
{
if (!isValid ())
throw std::runtime_error ("invalid proof of work target/iteration");
uint256 nonce;
RandomNumbers::getInstance ().fill (&nonce);
std::vector<uint256> buf2;
buf2.resize (mIterations);
std::vector<uint256> buf1;
buf1.resize (3);
buf1[0] = mChallenge;
while (maxIterations > 0)
{
buf1[1] = nonce;
buf1[2].zero ();
for (int i = (mIterations - 1); i >= 0; --i)
{
buf1[2] = getSHA512Half (buf1);
buf2[i] = buf1[2];
}
if (getSHA512Half (buf2) <= mTarget)
return nonce;
++nonce;
--maxIterations;
}
return uint256 ();
}
bool ProofOfWork::checkSolution (uint256 const& solution) const
{
if (mIterations > kMaxIterations)
return false;
std::vector<uint256> buf1;
buf1.push_back (mChallenge);
buf1.push_back (solution);
buf1.push_back (uint256 ());
std::vector<uint256> buf2;
buf2.resize (mIterations);
for (int i = (mIterations - 1); i >= 0; --i)
{
buf1[2] = getSHA512Half (buf1);
buf2[i] = buf1[2];
}
return getSHA512Half (buf2) <= mTarget;
}
std::pair<uint256, bool>
makeSharedValue (SSL* ssl, beast::Journal journal)
{
std::pair<uint256, bool> result = { {}, false };
unsigned char sha1[64];
unsigned char sha2[64];
if (!hashLastMessage(ssl, sha1, SSL_get_finished))
{
journal.error << "Cookie generation: local setup not complete";
return result;
}
if (!hashLastMessage(ssl, sha2, SSL_get_peer_finished))
{
journal.error << "Cookie generation: peer setup not complete";
return result;
}
// If both messages hash to the same value (i.e. match) something is
// wrong. This would cause the resulting cookie to be 0.
if (memcmp (sha1, sha2, sizeof (sha1)) == 0)
{
journal.error << "Cookie generation: identical finished messages";
return result;
}
for (size_t i = 0; i < sizeof (sha1); ++i)
sha1[i] ^= sha2[i];
// Finally, derive the actual cookie for the values that
// we have calculated.
result.first = getSHA512Half (sha1, sizeof(sha1));
result.second = true;
return result;
}
