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// Copyright (c) 2012-2013 The PPCoin developers
// Distributed under the GPL3 software license, see the accompanying
// file COPYING or
#include "kernel.h"
#include "util.h"
#include "chainparams.h"
#include "validation.h"
#include "streams.h"
#include "uint256hm.h"
#include "wallet/wallet.h"
#include "timedata.h"
#include "consensus/validation.h"
#include "txdb.h"
using namespace std;
// Hard checkpoints of stake modifiers to ensure they are deterministic
static std::map<int, unsigned int> mapStakeModifierCheckpoints =
{ 0, 0x0e00670bu },
{ 19000, 0xb185c126u }
// Get the last stake modifier and its generation time from a given block
static bool GetLastStakeModifier(const CBlockIndex* pindex, uint64_t& nStakeModifier, int64_t& nModifierTime)
if (!pindex)
return error("%s: null pindex", __func__);
do {
if (pindex->GeneratedStakeModifier()) {
nStakeModifier = pindex->nStakeModifier;
nModifierTime = pindex->GetBlockTime();
return true;
} while ((pindex = pindex->pprev) != NULL);
return error("%s: no generation at genesis block", __func__);
// Get selection interval section (in seconds)
static int64_t GetStakeModifierSelectionIntervalSection(int nSection)
assert (nSection >= 0 && nSection < 64);
return (Params().GetConsensus().nStakeModifierInterval * 63 / (63 + ((63 - nSection) * (MODIFIER_INTERVAL_RATIO - 1))));
// Get stake modifier selection interval (in seconds)
static int64_t GetStakeModifierSelectionInterval()
static int64_t nSelectionInterval = -1;
if (nSelectionInterval < 0) {
nSelectionInterval = 0;
for (int nSection=0; nSection<64; nSection++)
nSelectionInterval += GetStakeModifierSelectionIntervalSection(nSection);
return nSelectionInterval;
// select a block from the candidate blocks in vSortedByTimestamp, excluding
// already selected blocks in vSelectedBlocks, and with timestamp up to
// nSelectionIntervalStop.
static bool SelectBlockFromCandidates(
vector<pair<const CBlockIndex*, arith_uint256> >& vSortedByTimestamp,
int64_t nSelectionIntervalStop, uint64_t nStakeModifierPrev,
const CBlockIndex** pindexSelected)
arith_uint256 zero = 0;
pair<const CBlockIndex*, arith_uint256> *itemSelected = NULL;
for (auto& item : vSortedByTimestamp) {
const CBlockIndex* pindex = item.first;
if (pindex == NULL)
continue; // This block already has been selected
if (itemSelected != NULL && pindex->GetBlockTime() > nSelectionIntervalStop)
if (itemSelected == NULL || item.second < itemSelected->second) {
// compute the selection hash by hashing its proof-hash and the
// previous proof-of-stake modifier
if (item.second == zero) {
uint256 hashProof = pindex->IsProofOfStake()? pindex->hashProofOfStake : pindex->GetBlockHash();
CDataStream ss(SER_GETHASH, 0);
ss << hashProof << nStakeModifierPrev;
item.second = UintToArith256(Hash(ss.begin(), ss.end()));
// the selection hash is divided by 2**32 so that proof-of-stake block
// is always favored over proof-of-work block. this is to preserve
// the energy efficiency property
if (pindex->IsProofOfStake())
item.second >>= 32;
if (itemSelected != NULL && item.second >= itemSelected->second)
itemSelected = &item;
} // for
if (itemSelected) {
*pindexSelected = itemSelected->first;
itemSelected->first = NULL;
return true;
} else {
*pindexSelected = (const CBlockIndex*) 0;
return false;
// if (fDebug && GetBoolArg("-printstakemodifier", false))
// LogPrintf("%s: selection hash=%s\n", __func__, hashBest.ToString());
static void SwapSort(vector<pair<const CBlockIndex*, arith_uint256> > &v, unsigned pos) {
if(pos >= v.size() - 1)
pair<const CBlockIndex*, arith_uint256> &a = v[pos];
pair<const CBlockIndex*, arith_uint256> &b = v[pos + 1];
if (a.first->GetBlockTime() < b.first->GetBlockTime())
if (a.first->GetBlockTime() == b.first->GetBlockTime()) {
const uint256& ha = a.first->GetBlockHash(); // needed because of weird g++ (5.4.0 20160609) bug
const uint256& hb = b.first->GetBlockHash();
const uint32_t *pa = ha.GetDataPtr();
const uint32_t *pb = hb.GetDataPtr();
int cnt = 256 / 32;
for( ; ; ) {
if(pa[cnt] < pb[cnt])
if(pa[cnt] > pb[cnt])
break; // go to swap
if(cnt == 0)
std::swap(a, b);
SwapSort(v, pos - 1);
SwapSort(v, pos + 1);
} // SwapSort
// Stake Modifier (hash modifier of proof-of-stake):
// The purpose of stake modifier is to prevent a txout (coin) owner from
// computing future proof-of-stake generated by this txout at the time
// of transaction confirmation. To meet kernel protocol, the txout
// must hash with a future stake modifier to generate the proof.
// Stake modifier consists of bits each of which is contributed from a
// selected block of a given block group in the past.
// The selection of a block is based on a hash of the block's proof-hash and
// the previous stake modifier.
// Stake modifier is recomputed at a fixed time interval instead of every
// block. This is to make it difficult for an attacker to gain control of
// additional bits in the stake modifier, even after generating a chain of
// blocks.
bool ComputeNextStakeModifier(const CBlockIndex* pindexCurrent, uint64_t& nStakeModifier, bool& fGeneratedStakeModifier)
const CBlockIndex* pindexPrev = pindexCurrent->pprev;
nStakeModifier = 0;
fGeneratedStakeModifier = false;
if (!pindexPrev)
fGeneratedStakeModifier = true;
return true; // genesis block's modifier is 0
// First find current stake modifier and its generation block time
// if it's not old enough, return the same stake modifier
int64_t nModifierTime = 0;
if (!GetLastStakeModifier(pindexPrev, nStakeModifier, nModifierTime))
return error("%s: unable to get last modifier", __func__);
static int fPrint =-1;
if (fPrint < 0)
fPrint = GetBoolArg("-printstakemodifier", false);
if (fPrint)
LogPrintf("%s: prev modifier=0x%016x time=%s epoch=%u\n", __func__, nStakeModifier, DateTimeStrFormat(nModifierTime), (unsigned int)nModifierTime);
const Consensus::Params& params = Params().GetConsensus();
if (nModifierTime / params.nStakeModifierInterval >= pindexPrev->GetBlockTime() / params.nStakeModifierInterval)
// if (nModifierTime + params.nStakeModifierInterval > pindexPrev->GetBlockTime())
if (fPrint)
LogPrintf("%s: no new interval keep current modifier: pindexPrev nHeight=%d nTime=%u\n", __func__, pindexPrev->nHeight, (unsigned int)pindexPrev->GetBlockTime());
return true;
if (nModifierTime / params.nStakeModifierInterval >= pindexCurrent->GetBlockTime() / params.nStakeModifierInterval)
// if (nModifierTime + params.nStakeModifierInterval > pindexCurrent->GetBlockTime())
// v0.4+ requires current block timestamp also be in a different modifier interval
if (IsProtocolV04(pindexCurrent->nTime))
if (fPrint)
LogPrintf("%s: (v0.3.5+) no new interval keep current modifier: pindexCurrent nHeight=%d nTime=%u\n", __func__, pindexCurrent->nHeight, (unsigned int)pindexCurrent->GetBlockTime());
return true;
else if (fPrint)
LogPrintf("%s: v0.3.4 modifier at block %s not meeting v0.4+ protocol: pindexCurrent nHeight=%d nTime=%u\n", __func__, pindexCurrent->GetBlockHash().ToString(), pindexCurrent->nHeight, (unsigned int)pindexCurrent->GetBlockTime());
// Sort candidate blocks by timestamp
vector<pair<const CBlockIndex*, arith_uint256> > vSortedByTimestamp;
vSortedByTimestamp.reserve(64 * params.nStakeModifierInterval / params.nStakeTargetSpacing + 1);
int64_t nSelectionInterval = GetStakeModifierSelectionInterval();
int64_t nSelectionIntervalStart = (pindexPrev->GetBlockTime() / params.nStakeModifierInterval) * params.nStakeModifierInterval - nSelectionInterval;
const CBlockIndex* pindex = pindexPrev;
while (pindex && pindex->GetBlockTime() >= nSelectionIntervalStart)
if (!mapBlockIndex.count(pindex->GetBlockHash()))
return error("%s: failed to find block index for candidate block %s", __func__, pindex->GetBlockHash().ToString());
vSortedByTimestamp.push_back(make_pair(pindex, 0));
pindex = pindex->pprev;
reverse(vSortedByTimestamp.begin(), vSortedByTimestamp.end());
for(int i = 0; i < (int)vSortedByTimestamp.size() - 1; i++)
SwapSort(vSortedByTimestamp, i);
// Select 64 blocks from candidate blocks to generate stake modifier
uint64_t nStakeModifierNew = 0;
int64_t nSelectionIntervalStop = nSelectionIntervalStart;
for (int nRound=0; nRound<min(64, (int)vSortedByTimestamp.size()); nRound++)
// add an interval section to the current selection round
nSelectionIntervalStop += GetStakeModifierSelectionIntervalSection(nRound);
// select a block from the candidates of current round
if (!SelectBlockFromCandidates(vSortedByTimestamp, nSelectionIntervalStop, nStakeModifier, &pindex))
return error("%s: unable to select block at round %d", __func__, nRound);
// write the entropy bit of the selected block
nStakeModifierNew |= (((uint64_t)pindex->GetStakeEntropyBit()) << nRound);
// add the selected block from candidates to selected list
if (fDebug && GetBoolArg("-printstakemodifier", false))
LogPrintf("%s: selected round %d stop=%s height=%d bit=%d\n", __func__,
nRound, DateTimeStrFormat(nSelectionIntervalStop), pindex->nHeight, pindex->GetStakeEntropyBit());
if (fPrint)
LogPrintf("%s: new modifier=0x%016x time=%s\n", __func__, nStakeModifierNew, DateTimeStrFormat(pindexPrev->GetBlockTime()));
nStakeModifier = nStakeModifierNew;
fGeneratedStakeModifier = true;
return true;
// V0.5: Stake modifier used to hash for a stake kernel is chosen as the stake
// modifier that is (nStakeMinAge minus a selection interval) earlier than the
// stake, thus at least a selection interval later than the coin generating the // kernel, as the generating coin is from at least nStakeMinAge ago.
static bool GetKernelStakeModifierV05(CBlockIndex* pindexPrev, unsigned int nTimeTx, uint64_t& nStakeModifier, int& nStakeModifierHeight, int64_t& nStakeModifierTime, bool fPrintProofOfStake)
const Consensus::Params& params = Params().GetConsensus();
const CBlockIndex* pindex = pindexPrev;
nStakeModifierHeight = pindex->nHeight;
nStakeModifierTime = pindex->GetBlockTime();
int64_t nStakeModifierSelectionInterval = GetStakeModifierSelectionInterval();
if (nStakeModifierTime + params.nStakeMinAge - nStakeModifierSelectionInterval <= (int64_t) nTimeTx)
// Best block is still more than
// (nStakeMinAge minus a selection interval) older than kernel timestamp
if (fPrintProofOfStake)
return error("GetKernelStakeModifier() : best block %s at height %d too old for stake",
pindex->GetBlockHash().ToString(), pindex->nHeight);
return false;
static int64_t cache_TimeTxBarrier = 0;
static int64_t cache_nStakeModifierTime, cache_nStakeModifierTime_in;
static uint64_t cache_nStakeModifier;
static int cache_nStakeModifierHeight;
static unsigned int cache_nTimeTx;
#if 1
if(nTimeTx <= cache_TimeTxBarrier && nStakeModifierTime >= cache_nStakeModifierTime_in && nTimeTx >= cache_nTimeTx) {
nStakeModifier = cache_nStakeModifier;
nStakeModifierTime = cache_nStakeModifierTime;
nStakeModifierHeight = cache_nStakeModifierHeight;
return true;
cache_nStakeModifierTime_in = nStakeModifierTime;
// loop to find the stake modifier earlier by
// (nStakeMinAge minus a selection interval)
while (nStakeModifierTime + params.nStakeMinAge - nStakeModifierSelectionInterval >(int64_t) nTimeTx)
if (!pindex->pprev)
{ // reached genesis block; should not happen
return error("GetKernelStakeModifier() : reached genesis block");
pindex = pindex->pprev;
if (pindex->GeneratedStakeModifier())
cache_TimeTxBarrier = nStakeModifierTime + params.nStakeMinAge - nStakeModifierSelectionInterval;
nStakeModifierHeight = pindex->nHeight;
nStakeModifierTime = pindex->GetBlockTime();
} // while
cache_nStakeModifier = nStakeModifier = pindex->nStakeModifier;
cache_nStakeModifierHeight = nStakeModifierHeight;
cache_nStakeModifierTime = nStakeModifierTime;
cache_nTimeTx = nTimeTx;
return true;
// The stake modifier used to hash for a stake kernel is chosen as the stake
// modifier about a selection interval later than the coin generating the kernel
static bool GetKernelStakeModifierV03(CBlockIndex* pindexPrev, uint256 hashBlockFrom, uint64_t& nStakeModifier, int& nStakeModifierHeight, int64_t& nStakeModifierTime, bool fPrintProofOfStake)
const Consensus::Params& params = Params().GetConsensus();
nStakeModifier = 0;
if (!mapBlockIndex.count(hashBlockFrom))
return error("%s: block not indexed", __func__);
const CBlockIndex* pindexFrom = mapBlockIndex[hashBlockFrom];
nStakeModifierHeight = pindexFrom->nHeight;
nStakeModifierTime = pindexFrom->GetBlockTime();
int64_t nStakeModifierSelectionInterval = GetStakeModifierSelectionInterval();
// emercoin: we need to iterate index forward but we cannot use chainActive.Next()
// because there is no guarantee that we are checking blocks in active chain.
// So, we construct a temporary chain that we will iterate over.
// pindexFrom - this block contains coins that are used to generate PoS
// pindexPrev - this is a block that is previous to PoS block that we are checking, you can think of it as tip of our chain
// tmpChain should contain all indexes in [pindexFrom..pindexPrev] (inclusive)
std::vector<CBlockIndex*> tmpChain;
int32_t nDepth = pindexPrev->nHeight - (pindexFrom->nHeight-1); // -1 is used to also include pindexFrom
CBlockIndex* it = pindexPrev;
for (int i=1; i<=nDepth && !chainActive.Contains(it); i++) {
it = it->pprev;
std::reverse(tmpChain.begin(), tmpChain.end());
size_t n = 0;
const CBlockIndex* pindex = pindexFrom;
// loop to find the stake modifier later by a selection interval
while (nStakeModifierTime < pindexFrom->GetBlockTime() + nStakeModifierSelectionInterval)
const CBlockIndex* old_pindex = pindex;
pindex = (!tmpChain.empty() && pindex->nHeight >= tmpChain[0]->nHeight - 1)? tmpChain[n++] : chainActive.Next(pindex);
if (n > tmpChain.size() || pindex == NULL) // check if tmpChain[n+1] exists
{ // reached best block; may happen if node is behind on block chain
if (fPrintProofOfStake || (old_pindex->GetBlockTime() + params.nStakeMinAge - nStakeModifierSelectionInterval > GetAdjustedTime()))
return error("%s: reached best block %s at height %d from block %s", __func__,
old_pindex->GetBlockHash().ToString(), old_pindex->nHeight, hashBlockFrom.ToString());
return false;
if (pindex->GeneratedStakeModifier())
nStakeModifierHeight = pindex->nHeight;
nStakeModifierTime = pindex->GetBlockTime();
nStakeModifier = pindex->nStakeModifier;
return true;
// Get the stake modifier specified by the protocol to hash for a stake kernel
static bool GetKernelStakeModifier(CBlockIndex* pindexPrev, uint256 hashBlockFrom, unsigned int nTimeTx, uint64_t& nStakeModifier, int& nStakeModifierHeight, int64_t& nStakeModifierTime, bool fPrintProofOfStake)
if (IsProtocolV05(nTimeTx))
return GetKernelStakeModifierV05(pindexPrev, nTimeTx, nStakeModifier, nStakeModifierHeight, nStakeModifierTime, fPrintProofOfStake);
return GetKernelStakeModifierV03(pindexPrev, hashBlockFrom, nStakeModifier, nStakeModifierHeight, nStakeModifierTime, fPrintProofOfStake);
// ppcoin kernel protocol
// coinstake must meet hash target according to the protocol:
// kernel (input 0) must meet the formula
// hash(nStakeModifier + txPrev.block.nTime + txPrev.offset + txPrev.nTime + txPrev.vout.n + nTime) < bnTarget * nCoinDayWeight
// this ensures that the chance of getting a coinstake is proportional to the
// amount of coin age one owns.
// The reason this hash is chosen is the following:
// nStakeModifier:
// (v0.5) uses dynamic stake modifier around 21 days before the kernel,
// versus static stake modifier about 9 days after the staked
// coin (txPrev) used in v0.3
// (v0.3) scrambles computation to make it very difficult to precompute
// future proof-of-stake at the time of the coin's confirmation
// (v0.2) nBits (deprecated): encodes all past block timestamps
// txPrev.block.nTime: prevent nodes from guessing a good timestamp to
// generate transaction for future advantage
// txPrev.offset: offset of txPrev inside block, to reduce the chance of
// nodes generating coinstake at the same time
// txPrev.nTime: reduce the chance of nodes generating coinstake at the same
// time
// txPrev.vout.n: output number of txPrev, to reduce the chance of nodes
// generating coinstake at the same time
// block/tx hash should not be used here as they can be generated in vast
// quantities so as to generate blocks faster, degrading the system back into
// a proof-of-work situation.
bool CheckStakeKernelHash(unsigned int nBits, CBlockIndex* pindexPrev, const CBlockHeader& blockFrom, unsigned int nTxPrevOffset, const CTransactionRef& txPrev, const COutPoint& prevout, unsigned int nTimeTx, uint256& hashProofOfStake, bool fPrintProofOfStake)
const Consensus::Params& params = Params().GetConsensus();
if (nTimeTx < txPrev->nTime) // Transaction timestamp violation
return error("%s: nTime violation", __func__);
unsigned int nTimeBlockFrom = blockFrom.GetBlockTime();
if (nTimeBlockFrom + params.nStakeMinAge > nTimeTx) // Min age requirement
return error("%s: min age violation", __func__);
arith_uint256 bnTargetPerCoinDay;
int64_t nValueIn = txPrev->vout[prevout.n].nValue;
// v0.3 protocol kernel hash weight starts from 0 at the 30-day min age
// this change increases active coins participating the hash and helps
// to secure the network when proof-of-stake difficulty is low
int64_t nTimeWeight = min((int64_t)nTimeTx - txPrev->nTime, params.nStakeMaxAge) - (IsProtocolV03(nTimeTx)? params.nStakeMinAge : 0);
arith_uint256 bnCoinDayWeight = arith_uint256(nValueIn) * nTimeWeight / COIN / (24 * 60 * 60);
// Calculate hash
CDataStream ss(SER_GETHASH, 0);
uint64_t nStakeModifier = 0;
int nStakeModifierHeight = 0;
int64_t nStakeModifierTime = 0;
if (IsProtocolV03(nTimeTx)) // v0.3 protocol
if (!GetKernelStakeModifier(pindexPrev, blockFrom.GetHash(), nTimeTx, nStakeModifier, nStakeModifierHeight, nStakeModifierTime, fPrintProofOfStake))
return false;
ss << nStakeModifier;
else // v0.2 protocol
ss << nBits;
ss << nTimeBlockFrom << nTxPrevOffset << txPrev->nTime << prevout.n << nTimeTx;
if (nTimeTx >= 1489782503 && !IsProtocolV05(nTimeTx)) // block 219831, until 06/18/2019
ss << pindexPrev->GetBlockHash();
hashProofOfStake = Hash(ss.begin(), ss.end());
if (fPrintProofOfStake)
if (IsProtocolV03(nTimeTx))
LogPrintf("%s: using modifier 0x%016x at height=%d timestamp=%s for block from height=%d timestamp=%s\n", __func__,
nStakeModifier, nStakeModifierHeight,
LogPrintf("%s: check protocol=%s modifier=0x%016x nTimeBlockFrom=%u nTxPrevOffset=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n", __func__,
IsProtocolV05(nTimeTx)? "0.5" : (IsProtocolV03(nTimeTx)? "0.3" : "0.2"),
IsProtocolV03(nTimeTx)? nStakeModifier : (uint64_t) nBits,
nTimeBlockFrom, nTxPrevOffset, txPrev->nTime, prevout.n, nTimeTx,
// Now check if proof-of-stake hash meets target protocol
if (UintToArith256(hashProofOfStake) > bnCoinDayWeight * bnTargetPerCoinDay)
return false;
if (fDebug && !fPrintProofOfStake)
if (IsProtocolV03(nTimeTx))
LogPrintf("%s: using modifier 0x%016x at height=%d timestamp=%s for block from height=%d timestamp=%s\n", __func__,
nStakeModifier, nStakeModifierHeight,
LogPrintf("%s: pass protocol=%s modifier=0x%016x nTimeBlockFrom=%u nTxPrevOffset=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n", __func__,
IsProtocolV03(nTimeTx)? "0.3" : "0.2",
IsProtocolV03(nTimeTx)? nStakeModifier : (uint64_t) nBits,
nTimeBlockFrom, nTxPrevOffset, txPrev->nTime, prevout.n, nTimeTx,
return true;
// Check kernel hash target and coinstake signature
bool CheckProofOfStake(CValidationState& state, CBlockIndex* pindexPrev, const CTransactionRef& tx, unsigned int nBits, uint256& hashProofOfStake)
if (!tx->IsCoinStake())
return error("%s: called on non-coinstake %s", __func__, tx->GetHash().ToString());
// Kernel (input 0) must match the stake hash target per coin age (nBits)
const CTxIn& txin = tx->vin[0];
// Transaction index is required to get to block header
if (!fTxIndex)
return error("%s: transaction index not available", __func__);
// First try finding the previous transaction in database
CTransactionRef txTmp;
uint256 hashBlock = uint256();
if (!GetTransaction(txin.prevout.hash, txTmp, Params().GetConsensus(), hashBlock))
// previous transaction not in main chain, may occur during initial download
return state.DoS(1, false, REJECT_INVALID, "prev-tx-not-found", false, strprintf("%s: txPrev not found", __func__));
// Verify signature
CCoins coins(*txTmp, 0);
PrecomputedTransactionData txdata(*tx);
if (!CScriptCheck(coins, *tx, 0, SCRIPT_VERIFY_P2SH, true, &txdata)())
return state.DoS(100, false, REJECT_INVALID, "invalid-pos-script", false, strprintf("%s: VerifyScript failed on coinstake %s", __func__, tx->GetHash().ToString()));
// Get transaction index for the previous transaction
CDiskTxPos postx;
if (!pblocktree->ReadTxIndex(txin.prevout.hash, postx))
return error("%s: tx index not found", __func__); // tx index not found
// Read txPrev and header of its block
CBlockHeader header;
CTransactionRef txPrev;
CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
try {
file >> header;
fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
file >> txPrev;
} catch (std::exception& e) {
return error("%s: deserialize or I/O error", __func__);
if (txPrev->GetHash() != txin.prevout.hash)
return error("%s: txid mismatch", __func__);
if (!CheckStakeKernelHash(nBits, pindexPrev, header, postx.nTxOffset + CBlockHeader::NORMAL_SERIALIZE_SIZE, txPrev, txin.prevout, tx->nTime, hashProofOfStake, fDebug))
// may occur during initial download or if behind on block chain sync
return state.DoS(1, false, REJECT_INVALID, "invalid-stake-hash", false, strprintf("%s: INFO: check kernel failed on coinstake %s, hashProof=%s", __func__, tx->GetHash().ToString(), hashProofOfStake.ToString()));
return true;
// Check whether the coinstake timestamp meets protocol
bool CheckCoinStakeTimestamp(int64_t nTimeBlock, int64_t nTimeTx)
if (IsProtocolV03(nTimeTx)) // v0.3 protocol
return (nTimeBlock == nTimeTx);
else // v0.2 protocol
return ((nTimeTx <= nTimeBlock) && (nTimeBlock <= nTimeTx + nMaxClockDrift));
// Get stake modifier checksum
unsigned int GetStakeModifierChecksum(const CBlockIndex* pindex)
assert (pindex->pprev || pindex->GetBlockHash() == Params().GetConsensus().hashGenesisBlock);
// Hash previous checksum with flags, hashProofOfStake and nStakeModifier
CDataStream ss(SER_GETHASH, 0);
if (pindex->pprev)
ss << pindex->pprev->nStakeModifierChecksum;
ss << pindex->nFlags << pindex->hashProofOfStake << pindex->nStakeModifier;
arith_uint256 hashChecksum = UintToArith256(Hash(ss.begin(), ss.end()));
hashChecksum >>= (256 - 32);
return hashChecksum.GetLow64();
// Check stake modifier hard checkpoints
bool CheckStakeModifierCheckpoints(int nHeight, unsigned int nStakeModifierChecksum)
if (Params().NetworkIDString() != "main") return true; // Testnet or Regtest has no checkpoints
if (mapStakeModifierCheckpoints.count(nHeight))
return nStakeModifierChecksum == mapStakeModifierCheckpoints[nHeight];
return true;
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