bnTargetPerCoinDay.SetCompact(nBits);
int64_t nValueIn = pcoin.first->vout[pcoin.second].nValue;
- // Search backward in time from the given timestamp
+ // Search backward in time from the given timestamp
// Search nSearchInterval seconds back up to nMaxStakeSearchInterval
// Stopping search in case of shutting down or cache invalidation
for (unsigned int n=0; n<nCurrentSearchInterval && fCoinsDataActual && !fShutdown; n++)
// Scan given input for kernel solution
bool ScanInputForStakeKernelHash(CTransaction &tx, uint32_t nOut, uint32_t nBits, uint32_t nSearchInterval, std::pair<uint256, uint32_t> &solution)
{
+ CTxDB txdb("r");
+
CBlock block;
CTxIndex txindex;
- uint256 hashProofOfStake;
-
- int nTime = GetTime();
-
- CTxDB txdb("r");
// Load transaction index item
if (!txdb.ReadTxIndex(tx.GetHash(), txindex))
if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
return false;
+ uint32_t nTime = GetTime();
+ // Only count coins meeting min age requirement
+ if (nStakeMinAge + block.nTime > nTime)
+ nTime += (nStakeMinAge + block.nTime - nTime);
+
// Transaction offset inside block
uint32_t nTxOffset = txindex.pos.nTxPos - txindex.pos.nBlockPos;
+ int64_t nValueIn = tx.vout[nOut].nValue;
- uint32_t nBlockTime = block.nTime;
CBigNum bnTargetPerCoinDay;
bnTargetPerCoinDay.SetCompact(nBits);
- int64_t nValueIn = tx.vout[nOut].nValue;
+
+ // Get maximum possible target to filter out the majority of obviously insufficient hashes
+ CBigNum bnMaxTargetPerCoinDay = bnTargetPerCoinDay * CBigNum(nValueIn) * nStakeMaxAge / COIN / (24 * 60 * 60);
+ uint256 maxTarget = bnMaxTargetPerCoinDay.getuint256();
+
+
+ // Build static part of kernel
+ CDataStream ssKernel(SER_GETHASH, 0);
+ ssKernel << nStakeModifier;
+ ssKernel << block.nTime << nTxOffset << tx.nTime << nOut;
+ CDataStream::const_iterator it = ssKernel.begin();
+
+ // Init sha256 context and update it
+ // with first 16 bytes of kernel
+ SHA256_CTX ctxCurrent;
+ SHA256_Init(&ctxCurrent);
+ SHA256_Update(&ctxCurrent, (unsigned char*)&it[0], 8 + 16);
+ SHA256_CTX ctxCopy = ctxCurrent;
// Search forward in time from the given timestamp
// Stopping search in case of shutting down
- for (unsigned int n=0; n<nSearchInterval && !fShutdown; n++)
+ for (uint32_t nTimeTx=nTime; nTimeTx<nTime+nSearchInterval && !fShutdown; nTimeTx++)
{
- uint32_t nTimeTx = nTime + n;
- CBigNum bnCoinDayWeight = CBigNum(nValueIn) * GetWeight((int64_t)tx.nTime, (int64_t)nTimeTx) / COIN / (24 * 60 * 60);
- CBigNum bnTargetProofOfStake = bnCoinDayWeight * bnTargetPerCoinDay;
+ // Complete first hashing iteration
+ uint256 hash1;
+ SHA256_Update(&ctxCurrent, (unsigned char*)&nTimeTx, 4);
+ SHA256_Final((unsigned char*)&hash1, &ctxCurrent);
- // Build kernel
- CDataStream ss(SER_GETHASH, 0);
- ss << nStakeModifier;
- ss << nBlockTime << nTxOffset << tx.nTime << nOut << nTimeTx;
+ // Restore old context
+ ctxCurrent = ctxCopy;
- // Calculate kernel hash
- hashProofOfStake = Hash(ss.begin(), ss.end());
+ // Finally, calculate kernel hash
+ uint256 hashProofOfStake;
+ SHA256((unsigned char*)&hash1, sizeof(hashProofOfStake), (unsigned char*)&hashProofOfStake);
+
+ // Skip if hash doesn't satisfy the maximum target
+ if (hashProofOfStake > maxTarget)
+ continue;
+
+ CBigNum bnCoinDayWeight = CBigNum(nValueIn) * GetWeight((int64_t)tx.nTime, (int64_t)nTimeTx) / COIN / (24 * 60 * 60);
+ CBigNum bnTargetProofOfStake = bnCoinDayWeight * bnTargetPerCoinDay;
if (bnTargetProofOfStake >= CBigNum(hashProofOfStake))
{