diff options
| -rw-r--r-- | doc/release-notes.md | 23 | ||||
| -rw-r--r-- | doc/release-process.md | 5 | ||||
| -rw-r--r-- | src/chainparams.cpp | 9 | ||||
| -rw-r--r-- | src/consensus/params.h | 1 | ||||
| -rw-r--r-- | src/init.cpp | 11 | ||||
| -rw-r--r-- | src/validation.cpp | 35 | ||||
| -rw-r--r-- | src/validation.h | 3 |
7 files changed, 75 insertions, 12 deletions
diff --git a/doc/release-notes.md b/doc/release-notes.md index 7d0d689684..cb3f7934ce 100644 --- a/doc/release-notes.md +++ b/doc/release-notes.md @@ -49,7 +49,7 @@ Low-level RPC changes than two arguments. Removal of Priority Estimation ------------------------------- +------------------------------- - Estimation of "priority" needed for a transaction to be included within a target number of blocks has been removed. The rpc calls are deprecated and will either @@ -71,6 +71,27 @@ P2P connection management - New connections to manually added peers are much faster. +Introduction of assumed-valid blocks +------------------------------------- + +- A significant portion of the initial block download time is spent verifying + scripts/signatures. Although the verification must pass to ensure the security + of the system, no other result from this verification is needed: If the node + knew the history of a given block were valid it could skip checking scripts + for its ancestors. + +- A new configuration option 'assumevalid' is provided to express this knowledge + to the software. Unlike the 'checkpoints' in the past this setting does not + force the use of a particular chain: chains that are consistent with it are + processed quicker, but other chains are still accepted if they'd otherwise + be chosen as best. Also unlike 'checkpoints' the user can configure which + block history is assumed true, this means that even outdated software can + sync more quickly if the setting is updated by the user. + +- Because the validity of a chain history is a simple objective fact it is much + easier to review this setting. As a result the software ships with a default + value adjusted to match the current chain shortly before release. The use + of this default value can be disabled by setting -assumevalid=0 0.14.0 Change log ================= diff --git a/doc/release-process.md b/doc/release-process.md index 61f05b0771..399ed25c91 100644 --- a/doc/release-process.md +++ b/doc/release-process.md @@ -13,6 +13,11 @@ Before every minor and major release: * Update version in sources (see below) * Write release notes (see below) * Update `src/chainparams.cpp` nMinimumChainWork with information from the getblockchaininfo rpc. +* Update `src/chainparams.cpp` defaultAssumeValid with information from the getblockhash rpc. + - The selected value must not be orphaned so it may be useful to set the value two blocks back from the tip. + - Testnet should be set some tens of thousands back from the tip due to reorgs there. + - This update should be reviewed with a reindex-chainstate with assumevalid=0 to catch any defect + that causes rejection of blocks in the past history. Before every major release: 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; |