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-rw-r--r--src/chainparams.cpp9
-rw-r--r--src/consensus/params.h1
-rw-r--r--src/init.cpp11
-rw-r--r--src/validation.cpp35
-rw-r--r--src/validation.h3
5 files changed, 48 insertions, 11 deletions
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 66b5d48fd9..d99f800f0a 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -99,6 +99,9 @@ public:
// The best chain should have at least this much work.
consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000002cb971dd56d1c583c20f90");
+ // By default assume that the signatures in ancestors of this block are valid.
+ consensus.defaultAssumeValid = uint256S("0x0000000000000000030abc968e1bd635736e880b946085c93152969b9a81a6e2"); //447235
+
/**
* The message start string is designed to be unlikely to occur in normal data.
* The characters are rarely used upper ASCII, not valid as UTF-8, and produce
@@ -201,6 +204,9 @@ public:
// The best chain should have at least this much work.
consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000000000198b4def2baa9338d6");
+ // By default assume that the signatures in ancestors of this block are valid.
+ consensus.defaultAssumeValid = uint256S("0x000000000871ee6842d3648317ccc8a435eb8cc3c2429aee94faff9ba26b05a0"); //1043841
+
pchMessageStart[0] = 0x0b;
pchMessageStart[1] = 0x11;
pchMessageStart[2] = 0x09;
@@ -283,6 +289,9 @@ public:
// The best chain should have at least this much work.
consensus.nMinimumChainWork = uint256S("0x00");
+ // By default assume that the signatures in ancestors of this block are valid.
+ consensus.defaultAssumeValid = uint256S("0x00");
+
pchMessageStart[0] = 0xfa;
pchMessageStart[1] = 0xbf;
pchMessageStart[2] = 0xb5;
diff --git a/src/consensus/params.h b/src/consensus/params.h
index edf445e1c7..3f98938f7e 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -62,6 +62,7 @@ struct Params {
int64_t nPowTargetTimespan;
int64_t DifficultyAdjustmentInterval() const { return nPowTargetTimespan / nPowTargetSpacing; }
uint256 nMinimumChainWork;
+ uint256 defaultAssumeValid;
};
} // namespace Consensus
diff --git a/src/init.cpp b/src/init.cpp
index 9ac69b7d39..877371b5d1 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -329,8 +329,7 @@ std::string HelpMessage(HelpMessageMode mode)
strUsage += HelpMessageOpt("-blocknotify=<cmd>", _("Execute command when the best block changes (%s in cmd is replaced by block hash)"));
if (showDebug)
strUsage += HelpMessageOpt("-blocksonly", strprintf(_("Whether to operate in a blocks only mode (default: %u)"), DEFAULT_BLOCKSONLY));
- strUsage += HelpMessageOpt("-checkblocks=<n>", strprintf(_("How many blocks to check at startup (default: %u, 0 = all)"), DEFAULT_CHECKBLOCKS));
- strUsage += HelpMessageOpt("-checklevel=<n>", strprintf(_("How thorough the block verification of -checkblocks is (0-4, default: %u)"), DEFAULT_CHECKLEVEL));
+ strUsage +=HelpMessageOpt("-assumevalid=<hex>", strprintf(_("If this block is in the chain assume that it and its ancestors are valid and potentially skip their script verification (0 to verify all, default: %s, testnet: %s)"), Params(CBaseChainParams::MAIN).GetConsensus().defaultAssumeValid.GetHex(), Params(CBaseChainParams::TESTNET).GetConsensus().defaultAssumeValid.GetHex()));
strUsage += HelpMessageOpt("-conf=<file>", strprintf(_("Specify configuration file (default: %s)"), BITCOIN_CONF_FILENAME));
if (mode == HMM_BITCOIND)
{
@@ -420,6 +419,8 @@ std::string HelpMessage(HelpMessageMode mode)
strUsage += HelpMessageOpt("-uacomment=<cmt>", _("Append comment to the user agent string"));
if (showDebug)
{
+ strUsage += HelpMessageOpt("-checkblocks=<n>", strprintf(_("How many blocks to check at startup (default: %u, 0 = all)"), DEFAULT_CHECKBLOCKS));
+ strUsage += HelpMessageOpt("-checklevel=<n>", strprintf(_("How thorough the block verification of -checkblocks is (0-4, default: %u)"), DEFAULT_CHECKLEVEL));
strUsage += HelpMessageOpt("-checkblockindex", strprintf("Do a full consistency check for mapBlockIndex, setBlockIndexCandidates, chainActive and mapBlocksUnlinked occasionally. Also sets -checkmempool (default: %u)", Params(CBaseChainParams::MAIN).DefaultConsistencyChecks()));
strUsage += HelpMessageOpt("-checkmempool=<n>", strprintf("Run checks every <n> transactions (default: %u)", Params(CBaseChainParams::MAIN).DefaultConsistencyChecks()));
strUsage += HelpMessageOpt("-checkpoints", strprintf("Disable expensive verification for known chain history (default: %u)", DEFAULT_CHECKPOINTS_ENABLED));
@@ -920,6 +921,12 @@ bool AppInitParameterInteraction()
fCheckBlockIndex = GetBoolArg("-checkblockindex", chainparams.DefaultConsistencyChecks());
fCheckpointsEnabled = GetBoolArg("-checkpoints", DEFAULT_CHECKPOINTS_ENABLED);
+ hashAssumeValid = uint256S(GetArg("-assumevalid", chainparams.GetConsensus().defaultAssumeValid.GetHex()));
+ if (!hashAssumeValid.IsNull())
+ LogPrintf("Assuming ancestors of block %s have valid signatures.\n", hashAssumeValid.GetHex());
+ else
+ LogPrintf("Validating signatures for all blocks.\n");
+
// mempool limits
int64_t nMempoolSizeMax = GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
int64_t nMempoolSizeMin = GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT) * 1000 * 40;
diff --git a/src/validation.cpp b/src/validation.cpp
index 3faa1bf005..69aa018730 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -78,6 +78,7 @@ uint64_t nPruneTarget = 0;
int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
bool fEnableReplacement = DEFAULT_ENABLE_REPLACEMENT;
+uint256 hashAssumeValid;
CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
@@ -1389,11 +1390,10 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsVi
// Only if ALL inputs pass do we perform expensive ECDSA signature checks.
// Helps prevent CPU exhaustion attacks.
- // Skip ECDSA signature verification when connecting blocks before the
- // last block chain checkpoint. Assuming the checkpoints are valid this
+ // Skip script verification when connecting blocks under the
+ // assumedvalid block. Assuming the assumedvalid block is valid this
// is safe because block merkle hashes are still computed and checked,
- // and any change will be caught at the next checkpoint. Of course, if
- // the checkpoint is for a chain that's invalid due to false scriptSigs
+ // Of course, if an assumed valid block is invalid due to false scriptSigs
// this optimization would allow an invalid chain to be accepted.
if (fScriptChecks) {
for (unsigned int i = 0; i < tx.vin.size(); i++) {
@@ -1721,11 +1721,28 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
}
bool fScriptChecks = true;
- if (fCheckpointsEnabled) {
- CBlockIndex *pindexLastCheckpoint = Checkpoints::GetLastCheckpoint(chainparams.Checkpoints());
- if (pindexLastCheckpoint && pindexLastCheckpoint->GetAncestor(pindex->nHeight) == pindex) {
- // This block is an ancestor of a checkpoint: disable script checks
- fScriptChecks = false;
+ if (!hashAssumeValid.IsNull()) {
+ // We've been configured with the hash of a block which has been externally verified to have a valid history.
+ // A suitable default value is included with the software and updated from time to time. Because validity
+ // relative to a piece of software is an objective fact these defaults can be easily reviewed.
+ // This setting doesn't force the selection of any particular chain but makes validating some faster by
+ // effectively caching the result of part of the verification.
+ BlockMap::const_iterator it = mapBlockIndex.find(hashAssumeValid);
+ if (it != mapBlockIndex.end()) {
+ if (it->second->GetAncestor(pindex->nHeight) == pindex &&
+ pindexBestHeader->GetAncestor(pindex->nHeight) == pindex &&
+ pindexBestHeader->nChainWork >= UintToArith256(chainparams.GetConsensus().nMinimumChainWork)) {
+ // This block is a member of the assumed verified chain and an ancestor of the best header.
+ // The equivalent time check discourages hashpower from extorting the network via DOS attack
+ // into accepting an invalid block through telling users they must manually set assumevalid.
+ // Requiring a software change or burying the invalid block, regardless of the setting, makes
+ // it hard to hide the implication of the demand. This also avoids having release candidates
+ // that are hardly doing any signature verification at all in testing without having to
+ // artificially set the default assumed verified block further back.
+ // The test against nMinimumChainWork prevents the skipping when denied access to any chain at
+ // least as good as the expected chain.
+ fScriptChecks = (GetBlockProofEquivalentTime(*pindexBestHeader, *pindex, *pindexBestHeader, chainparams.GetConsensus()) <= 60 * 60 * 24 * 7 * 2);
+ }
}
}
diff --git a/src/validation.h b/src/validation.h
index 40e8907724..f66f690775 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -186,6 +186,9 @@ extern CAmount maxTxFee;
extern int64_t nMaxTipAge;
extern bool fEnableReplacement;
+/** Block hash whose ancestors we will assume to have valid scripts without checking them. */
+extern uint256 hashAssumeValid;
+
/** Best header we've seen so far (used for getheaders queries' starting points). */
extern CBlockIndex *pindexBestHeader;