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kernel.cpp
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// Copyright (c) 2012-2019 The Peercoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <kernel.h>
#include <chainparams.h>
#include <util.h>
#include <validation.h>
#include <streams.h>
#include <timedata.h>
#include <bignum.h>
#include <txdb.h>
#include <consensus/validation.h>
#include <random.h>
#include <script/interpreter.h>
#include <boost/assign/list_of.hpp>
using namespace std;
// Protocol switch time of v0.3 kernel protocol
unsigned int nProtocolV03SwitchTime = 1363800000;
unsigned int nProtocolV03TestSwitchTime = 1359781000;
// Protocol switch time of v0.4 kernel protocol
unsigned int nProtocolV04SwitchTime = 1399300000;
unsigned int nProtocolV04TestSwitchTime = 1395700000;
// Protocol switch time of v0.5 kernel protocol
unsigned int nProtocolV05SwitchTime = 1461700000;
unsigned int nProtocolV05TestSwitchTime = 1447700000;
// Protocol switch time of v0.6 kernel protocol
// supermajority hardfork: actual fork will happen later than switch time
const unsigned int nProtocolV06SwitchTime = 1513050000; // Tue 12 Dec 03:40:00 UTC 2017
const unsigned int nProtocolV06TestSwitchTime = 1508198400; // Tue 17 Oct 00:00:00 UTC 2017
// Protocol switch time for 0.7 kernel protocol
const unsigned int nProtocolV07SwitchTime = 1552392000; // Tue 12 Mar 12:00:00 UTC 2019
const unsigned int nProtocolV07TestSwitchTime = 1541505600; // Tue 06 Nov 12:00:00 UTC 2018
// Switch time for new BIPs from bitcoin 0.16.x
const uint32_t nBTC16BIPsSwitchTime = 1569931200; // Tue 01 Oct 12:00:00 UTC 2019
const uint32_t nBTC16BIPsTestSwitchTime = 1554811200; // Tue 09 Apr 12:00:00 UTC 2019
// Hard checkpoints of stake modifiers to ensure they are deterministic
static std::map<int, unsigned int> mapStakeModifierCheckpoints =
boost::assign::map_list_of
( 0, 0x0e00670bu )
( 19080, 0xad4e4d29u )
( 30583, 0xdc7bf136u )
( 99999, 0xf555cfd2u )
(219999, 0x91b7444du )
(336000, 0x6c3c8048u )
(371850, 0x9b850bdfu )
(407813, 0x46fe50b5u )
(443561, 0x114a6e38u )
;
static std::map<int, unsigned int> mapStakeModifierTestnetCheckpoints =
boost::assign::map_list_of
( 0, 0x0e00670bu )
( 19080, 0x3711dc3au )
( 30583, 0xb480fadeu )
( 99999, 0x9a62eaecu )
(219999, 0xeafe96c3u )
(336000, 0x8330dc09u )
(372751, 0xafb94e2fu )
(382019, 0x7f5cf5ebu )
(412691, 0x93138e67u )
;
// Whether the given coinstake is subject to new v0.3 protocol
bool IsProtocolV03(unsigned int nTimeCoinStake)
{
return (nTimeCoinStake >= (Params().NetworkIDString() != CBaseChainParams::MAIN ? nProtocolV03TestSwitchTime : nProtocolV03SwitchTime));
}
// Whether the given block is subject to new v0.4 protocol
bool IsProtocolV04(unsigned int nTimeBlock)
{
return (nTimeBlock >= (Params().NetworkIDString() != CBaseChainParams::MAIN ? nProtocolV04TestSwitchTime : nProtocolV04SwitchTime));
}
// Whether the given transaction is subject to new v0.5 protocol
bool IsProtocolV05(unsigned int nTimeTx)
{
return (nTimeTx >= (Params().NetworkIDString() != CBaseChainParams::MAIN ? nProtocolV05TestSwitchTime : nProtocolV05SwitchTime));
}
// Whether a given block is subject to new v0.6 protocol
// Test against previous block index! (always available)
bool IsProtocolV06(const CBlockIndex* pindexPrev)
{
if (pindexPrev->nTime < (Params().NetworkIDString() != CBaseChainParams::MAIN ? nProtocolV06TestSwitchTime : nProtocolV06SwitchTime))
return false;
// if 900 of the last 1,000 blocks are version 2 or greater (90/100 if testnet):
// Soft-forking PoS can be dangerous if the super majority is too low
// The stake majority will decrease after the fork
// since only coindays of updated nodes will get destroyed.
if ((Params().NetworkIDString() == CBaseChainParams::MAIN && IsSuperMajority(2, pindexPrev, 900, 1000)) ||
(Params().NetworkIDString() != CBaseChainParams::MAIN && IsSuperMajority(2, pindexPrev, 90, 100)))
return true;
return false;
}
// Whether a given transaction is subject to new v0.7 protocol
bool IsProtocolV07(unsigned int nTimeTx)
{
bool fTestNet = Params().NetworkIDString() != CBaseChainParams::MAIN;
return (nTimeTx >= (fTestNet? nProtocolV07TestSwitchTime : nProtocolV07SwitchTime));
}
bool IsBTC16BIPsEnabled(uint32_t nTimeTx)
{
bool fTestNet = Params().NetworkIDString() != CBaseChainParams::MAIN;
return (nTimeTx >= (fTestNet? nBTC16BIPsTestSwitchTime : nBTC16BIPsSwitchTime));
}
// 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("GetLastStakeModifier: null pindex");
while (pindex && pindex->pprev && !pindex->GeneratedStakeModifier())
pindex = pindex->pprev;
if (!pindex->GeneratedStakeModifier())
return error("GetLastStakeModifier: no generation at genesis block");
nStakeModifier = pindex->nStakeModifier;
nModifierTime = pindex->GetBlockTime();
return true;
}
// Get selection interval section (in seconds)
static int64_t GetStakeModifierSelectionIntervalSection(int nSection)
{
assert (nSection >= 0 && nSection < 64);
return (Params().GetConsensus().nModifierInterval * 63 / (63 + ((63 - nSection) * (MODIFIER_INTERVAL_RATIO - 1))));
}
// Get stake modifier selection interval (in seconds)
static int64_t GetStakeModifierSelectionInterval()
{
int64_t 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<int64_t, uint256> >& vSortedByTimestamp,
map<uint256, const CBlockIndex*>& mapSelectedBlocks,
int64_t nSelectionIntervalStop, uint64_t nStakeModifierPrev,
const CBlockIndex** pindexSelected)
{
bool fSelected = false;
arith_uint256 hashBest = 0;
*pindexSelected = (const CBlockIndex*) 0;
for (const auto& item : vSortedByTimestamp)
{
if (!mapBlockIndex.count(item.second))
return error("SelectBlockFromCandidates: failed to find block index for candidate block %s", item.second.ToString());
const CBlockIndex* pindex = mapBlockIndex[item.second];
if (fSelected && pindex->GetBlockTime() > nSelectionIntervalStop)
break;
if (mapSelectedBlocks.count(pindex->GetBlockHash()) > 0)
continue;
// compute the selection hash by hashing its proof-hash and the
// previous proof-of-stake modifier
uint256 hashProof = pindex->IsProofOfStake()? pindex->hashProofOfStake : pindex->GetBlockHash();
CDataStream ss(SER_GETHASH, 0);
ss << hashProof << nStakeModifierPrev;
arith_uint256 hashSelection = 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())
hashSelection >>= 32;
if (fSelected && hashSelection < hashBest)
{
hashBest = hashSelection;
*pindexSelected = (const CBlockIndex*) pindex;
}
else if (!fSelected)
{
fSelected = true;
hashBest = hashSelection;
*pindexSelected = (const CBlockIndex*) pindex;
}
}
if (gArgs.GetBoolArg("-debug", false) && gArgs.GetBoolArg("-printstakemodifier", false))
LogPrintf("SelectBlockFromCandidates: selection hash=%s\n", hashBest.ToString());
return fSelected;
}
// 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 Consensus::Params& params = Params().GetConsensus();
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("ComputeNextStakeModifier: unable to get last modifier");
if (gArgs.GetBoolArg("-debug", false))
LogPrintf("ComputeNextStakeModifier: prev modifier=0x%016x time=%s epoch=%u\n", nStakeModifier, DateTimeStrFormat(nModifierTime), (unsigned int)nModifierTime);
if (nModifierTime / params.nModifierInterval >= pindexPrev->GetBlockTime() / params.nModifierInterval)
{
if (gArgs.GetBoolArg("-debug", false))
LogPrintf("ComputeNextStakeModifier: no new interval keep current modifier: pindexPrev nHeight=%d nTime=%u\n", pindexPrev->nHeight, (unsigned int)pindexPrev->GetBlockTime());
return true;
}
if (nModifierTime / params.nModifierInterval >= pindexCurrent->GetBlockTime() / params.nModifierInterval)
{
// v0.4+ requires current block timestamp also be in a different modifier interval
if (IsProtocolV04(pindexCurrent->nTime))
{
if (gArgs.GetBoolArg("-debug", false))
LogPrintf("ComputeNextStakeModifier: (v0.4+) no new interval keep current modifier: pindexCurrent nHeight=%d nTime=%u\n", pindexCurrent->nHeight, (unsigned int)pindexCurrent->GetBlockTime());
return true;
}
else
{
if (gArgs.GetBoolArg("-debug", false))
LogPrintf("ComputeNextStakeModifier: v0.3 modifier at block %s not meeting v0.4+ protocol: pindexCurrent nHeight=%d nTime=%u\n", pindexCurrent->GetBlockHash().ToString(), pindexCurrent->nHeight, (unsigned int)pindexCurrent->GetBlockTime());
}
}
// Sort candidate blocks by timestamp
vector<pair<int64_t, uint256> > vSortedByTimestamp;
vSortedByTimestamp.reserve(64 * params.nModifierInterval / params.nStakeTargetSpacing);
int64_t nSelectionInterval = GetStakeModifierSelectionInterval();
int64_t nSelectionIntervalStart = (pindexPrev->GetBlockTime() / params.nModifierInterval) * params.nModifierInterval - nSelectionInterval;
const CBlockIndex* pindex = pindexPrev;
while (pindex && pindex->GetBlockTime() >= nSelectionIntervalStart)
{
vSortedByTimestamp.push_back(make_pair(pindex->GetBlockTime(), pindex->GetBlockHash()));
pindex = pindex->pprev;
}
int nHeightFirstCandidate = pindex ? (pindex->nHeight + 1) : 0;
// Shuffle before sort
for(int i = vSortedByTimestamp.size() - 1; i > 1; --i)
std::swap(vSortedByTimestamp[i], vSortedByTimestamp[GetRand(i)]);
sort(vSortedByTimestamp.begin(), vSortedByTimestamp.end(), [] (const pair<int64_t, uint256> &a, const pair<int64_t, uint256> &b)
{
if (a.first != b.first)
return a.first < b.first;
// Timestamp equals - compare block hashes
const uint32_t *pa = a.second.GetDataPtr();
const uint32_t *pb = b.second.GetDataPtr();
int cnt = 256 / 32;
do {
--cnt;
if (pa[cnt] != pb[cnt])
return pa[cnt] < pb[cnt];
} while(cnt);
return false; // Elements are equal
});
// Select 64 blocks from candidate blocks to generate stake modifier
uint64_t nStakeModifierNew = 0;
int64_t nSelectionIntervalStop = nSelectionIntervalStart;
map<uint256, const CBlockIndex*> mapSelectedBlocks;
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, mapSelectedBlocks, nSelectionIntervalStop, nStakeModifier, &pindex))
return error("ComputeNextStakeModifier: unable to select block at round %d", nRound);
// write the entropy bit of the selected block
nStakeModifierNew |= (((uint64_t)pindex->GetStakeEntropyBit()) << nRound);
// add the selected block from candidates to selected list
mapSelectedBlocks.insert(make_pair(pindex->GetBlockHash(), pindex));
if (gArgs.GetBoolArg("-debug", false) && gArgs.GetBoolArg("-printstakemodifier", false))
LogPrintf("ComputeNextStakeModifier: selected round %d stop=%s height=%d bit=%d\n",
nRound, DateTimeStrFormat(nSelectionIntervalStop), pindex->nHeight, pindex->GetStakeEntropyBit());
}
// Print selection map for visualization of the selected blocks
if (gArgs.GetBoolArg("-debug", false) && gArgs.GetBoolArg("-printstakemodifier", false))
{
string strSelectionMap = "";
// '-' indicates proof-of-work blocks not selected
strSelectionMap.insert(0, pindexPrev->nHeight - nHeightFirstCandidate + 1, '-');
pindex = pindexPrev;
while (pindex && pindex->nHeight >= nHeightFirstCandidate)
{
// '=' indicates proof-of-stake blocks not selected
if (pindex->IsProofOfStake())
strSelectionMap.replace(pindex->nHeight - nHeightFirstCandidate, 1, "=");
pindex = pindex->pprev;
}
for (const auto& item : mapSelectedBlocks)
{
// 'S' indicates selected proof-of-stake blocks
// 'W' indicates selected proof-of-work blocks
strSelectionMap.replace(item.second->nHeight - nHeightFirstCandidate, 1, item.second->IsProofOfStake()? "S" : "W");
}
LogPrintf("ComputeNextStakeModifier: selection height [%d, %d] map %s\n", nHeightFirstCandidate, pindexPrev->nHeight, strSelectionMap);
}
if (gArgs.GetBoolArg("-debug", false))
LogPrintf("ComputeNextStakeModifier: new modifier=0x%016x time=%s\n", 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);
else
return false;
}
// 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())
{
nStakeModifierHeight = pindex->nHeight;
nStakeModifierTime = pindex->GetBlockTime();
}
}
nStakeModifier = pindex->nStakeModifier;
return true;
}
// V0.3: 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("GetKernelStakeModifier() : block not indexed");
const CBlockIndex* pindexFrom = mapBlockIndex[hashBlockFrom];
nStakeModifierHeight = pindexFrom->nHeight;
nStakeModifierTime = pindexFrom->GetBlockTime();
int64_t nStakeModifierSelectionInterval = GetStakeModifierSelectionInterval();
// we need to iterate index forward but we cannot depend on 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
std::vector<CBlockIndex*> tmpChain;
int32_t nDepth = pindexPrev->nHeight - (pindexFrom->nHeight-1); // -1 is used to also include pindexFrom
tmpChain.reserve(nDepth);
CBlockIndex* it = pindexPrev;
for (int i=1; i<=nDepth && !chainActive.Contains(it); i++) {
tmpChain.push_back(it);
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("GetKernelStakeModifier() : reached best block %s at height %d from block %s",
old_pindex->GetBlockHash().ToString(), old_pindex->nHeight, hashBlockFrom.ToString());
else
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);
else
return GetKernelStakeModifierV03(pindexPrev, hashBlockFrom, nStakeModifier, nStakeModifierHeight, nStakeModifierTime, fPrintProofOfStake);
}
// peercoin 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("CheckStakeKernelHash() : nTime violation");
unsigned int nTimeBlockFrom = blockFrom.GetBlockTime();
if (nTimeBlockFrom + params.nStakeMinAge > nTimeTx) // Min age requirement
return error("CheckStakeKernelHash() : min age violation");
CBigNum bnTargetPerCoinDay;
bnTargetPerCoinDay.SetCompact(nBits);
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);
CBigNum bnCoinDayWeight = CBigNum(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;
hashProofOfStake = Hash(ss.begin(), ss.end());
if (fPrintProofOfStake)
{
if (IsProtocolV03(nTimeTx))
LogPrintf("CheckStakeKernelHash() : using modifier 0x%016x at height=%d timestamp=%s for block from height=%d timestamp=%s\n",
nStakeModifier, nStakeModifierHeight,
DateTimeStrFormat(nStakeModifierTime),
mapBlockIndex[blockFrom.GetHash()]->nHeight,
DateTimeStrFormat(blockFrom.GetBlockTime()));
LogPrintf("CheckStakeKernelHash() : check protocol=%s modifier=0x%016x nTimeBlockFrom=%u nTxPrevOffset=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n",
IsProtocolV05(nTimeTx)? "0.5" : (IsProtocolV03(nTimeTx)? "0.3" : "0.2"),
IsProtocolV03(nTimeTx)? nStakeModifier : (uint64_t) nBits,
nTimeBlockFrom, nTxPrevOffset, txPrev->nTime, prevout.n, nTimeTx,
hashProofOfStake.ToString());
}
// Now check if proof-of-stake hash meets target protocol
if (CBigNum(hashProofOfStake) > bnCoinDayWeight * bnTargetPerCoinDay)
return false;
if (gArgs.GetBoolArg("-debug", false) && !fPrintProofOfStake)
{
if (IsProtocolV03(nTimeTx))
LogPrintf("CheckStakeKernelHash() : using modifier 0x%016x at height=%d timestamp=%s for block from height=%d timestamp=%s\n",
nStakeModifier, nStakeModifierHeight,
DateTimeStrFormat(nStakeModifierTime),
mapBlockIndex[blockFrom.GetHash()]->nHeight,
DateTimeStrFormat(blockFrom.GetBlockTime()));
LogPrintf("CheckStakeKernelHash() : pass protocol=%s modifier=0x%016x nTimeBlockFrom=%u nTxPrevOffset=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n",
IsProtocolV03(nTimeTx)? "0.3" : "0.2",
IsProtocolV03(nTimeTx)? nStakeModifier : (uint64_t) nBits,
nTimeBlockFrom, nTxPrevOffset, txPrev->nTime, prevout.n, nTimeTx,
hashProofOfStake.ToString());
}
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("CheckProofOfStake() : called on non-coinstake %s", 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("CheckProofOfStake() : transaction index not available");
// Get transaction index for the previous transaction
CDiskTxPos postx;
if (!pblocktree->ReadTxIndex(txin.prevout.hash, postx))
return error("CheckProofOfStake() : tx index not found"); // 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 in CheckProofOfStake()", __PRETTY_FUNCTION__);
}
if (txPrev->GetHash() != txin.prevout.hash)
return error("%s() : txid mismatch in CheckProofOfStake()", __PRETTY_FUNCTION__);
}
// Verify signature
{
int nIn = 0;
const CTxOut& prevOut = txPrev->vout[tx->vin[nIn].prevout.n];
TransactionSignatureChecker checker(&(*tx), nIn, prevOut.nValue, PrecomputedTransactionData(*tx));
if (!VerifyScript(tx->vin[nIn].scriptSig, prevOut.scriptPubKey, &(tx->vin[nIn].scriptWitness), SCRIPT_VERIFY_P2SH, checker, nullptr))
return state.DoS(100, false, REJECT_INVALID, "invalid-pos-script", false, strprintf("%s: VerifyScript failed on coinstake %s", __func__, tx->GetHash().ToString()));
}
if (!CheckStakeKernelHash(nBits, pindexPrev, header, postx.nTxOffset + CBlockHeader::NORMAL_SERIALIZE_SIZE, txPrev, txin.prevout, tx->nTime, hashProofOfStake, gArgs.GetBoolArg("-debug", false)))
return state.DoS(1, error("CheckProofOfStake() : INFO: check kernel failed on coinstake %s, hashProof=%s", tx->GetHash().ToString(), hashProofOfStake.ToString())); // may occur during initial download or if behind on block chain sync
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 + MAX_FUTURE_BLOCK_TIME));
}
// 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)
{
bool fTestNet = Params().NetworkIDString() == CBaseChainParams::TESTNET;
if (fTestNet && mapStakeModifierTestnetCheckpoints.count(nHeight))
return nStakeModifierChecksum == mapStakeModifierTestnetCheckpoints[nHeight];
if (!fTestNet && mapStakeModifierCheckpoints.count(nHeight))
return nStakeModifierChecksum == mapStakeModifierCheckpoints[nHeight];
return true;
}
bool IsSuperMajority(int minVersion, const CBlockIndex* pstart, unsigned int nRequired, unsigned int nToCheck)
{
unsigned int nFound = 0;
for (unsigned int i = 0; i < nToCheck && nFound < nRequired && pstart != NULL; pstart = pstart->pprev )
{
if (!pstart->IsProofOfStake())
continue;
if (pstart->nVersion >= minVersion)
++nFound;
i++;
}
return (nFound >= nRequired);
}
// peercoin: entropy bit for stake modifier if chosen by modifier
unsigned int GetStakeEntropyBit(const CBlock& block)
{
unsigned int nEntropyBit = 0;
if (IsProtocolV04(block.nTime))
{
nEntropyBit = UintToArith256(block.GetHash()).GetLow64() & 1llu;// last bit of block hash
if (gArgs.GetBoolArg("-printstakemodifier", false))
LogPrintf("GetStakeEntropyBit(v0.4+): nTime=%u hashBlock=%s entropybit=%d\n", block.nTime, block.GetHash().ToString(), nEntropyBit);
}
else
{
// old protocol for entropy bit pre v0.4
uint160 hashSig = Hash160(block.vchBlockSig);
if (gArgs.GetBoolArg("-printstakemodifier", false))
LogPrintf("GetStakeEntropyBit(v0.3): nTime=%u hashSig=%s", block.nTime, hashSig.ToString());
nEntropyBit = hashSig.GetDataPtr()[4] >> 31; // take the first bit of the hash
if (gArgs.GetBoolArg("-printstakemodifier", false))
LogPrintf(" entropybit=%d\n", nEntropyBit);
}
return nEntropyBit;
}