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2015-10-06Test LowS in standardness, removes nuisance malleability vector.Gregory Maxwell
This adds SCRIPT_VERIFY_LOW_S to STANDARD_SCRIPT_VERIFY_FLAGS which will make the node require the canonical 'low-s' encoding for ECDSA signatures when relaying or mining. Consensus behavior is unchanged. The rational is explained in a81cd96805ce6b65cca3a40ebbd3b2eb428abb7b: Absent this kind of test ECDSA is not a strong signature as given a valid signature {r, s} both that value and {r, -s mod n} are valid. These two encodings have different hashes allowing third parties a vector to change users txids. These attacks are avoided by picking a particular form as canonical and rejecting the other form(s); in the of the LOW_S rule, the smaller of the two possible S values is used. If widely deployed this change would eliminate the last remaining known vector for nuisance malleability on boring SIGHASH_ALL p2pkh transactions. On the down-side it will block most transactions made by sufficiently out of date software. Unlike the other avenues to change txids on boring transactions this one was randomly violated by all deployed bitcoin software prior to its discovery. So, while other malleability vectors where made non-standard as soon as they were discovered, this one has remained permitted. Even BIP62 did not propose applying this rule to old version transactions, but conforming implementations have become much more common since BIP62 was initially written. Bitcoin Core has produced compatible signatures since a28fb70e in September 2013, but this didn't make it into a release until 0.9 in March 2014; Bitcoinj has done so for a similar span of time. Bitcoinjs and electrum have been more recently updated. This does not replace the need for BIP62 or similar, as miners can still cooperate to break transactions. Nor does it replace the need for wallet software to handle malleability sanely[1]. This only eliminates the cheap and irritating DOS attack. [1] On the Malleability of Bitcoin Transactions Marcin Andrychowicz, Stefan Dziembowski, Daniel Malinowski, Łukasz Mazurek http://fc15.ifca.ai/preproceedings/bitcoin/paper_9.pdf
2015-10-01Accept any sequence of PUSHDATAs in OP_RETURN outputsPeter Todd
Previously only one PUSHDATA was allowed, needlessly limiting applications such as matching OP_RETURN contents with bloom filters that operate on a per-PUSHDATA level. Now any combination that passes IsPushOnly() is allowed, so long as the total size of the scriptPubKey is less than 42 bytes. (unchanged modulo non-minimal PUSHDATA encodings) Also, this fixes the odd bug where previously the PUSHDATA could be replaced by any single opcode, even sigops consuming opcodes such as CHECKMULTISIG. (20 sigops!)
2015-08-10typofixes (found by misspell_fixer)Veres Lajos
2015-08-03Make sure LogPrintf strings are line-terminatedWladimir J. van der Laan
Fix the cases where LogPrint[f] was accidentally called without line terminator, which resulted in concatenated log lines. (see e.g. #6492)
2015-06-26Policy: MOVEONLY: 3 functions to policy.o:Luke Dashjr
- [script/standard.o] IsStandard - [main.o] IsStandardTx - [main.o] AreInputsStandard Also, don't use namespace std in policy.cpp
2015-06-26Policy: MOVEONLY: Create policy/policy.h with some constantsJorge Timón
2015-05-13Create new BlockPolicyEstimator for fee estimatesAlex Morcos
This class groups transactions that have been confirmed in blocks into buckets, based on either their fee or their priority. Then for each bucket, the class calculates what percentage of the transactions were confirmed within various numbers of blocks. It does this by keeping an exponentially decaying moving history for each bucket and confirm block count of the percentage of transactions in that bucket that were confirmed within that number of blocks. -Eliminate txs which didn't have all inputs available at entry from fee/pri calcs -Add dynamic breakpoints and tracking of confirmation delays in mempool transactions -Remove old CMinerPolicyEstimator and CBlockAverage code -New smartfees.py -Pass a flag to the estimation code, using IsInitialBlockDownload as a proxy for when we are still catching up and we shouldn't be counting how many blocks it takes for transactions to be included. -Add a policyestimator unit test