This commit contains fixes from the results of a thorough audit of
txscript to find any cases of script evaluation which doesn't match the
required consensus behavior. These conditions are fairly obscure and
highly unlikely to happen in any real scripts, but they could have
nevertheless been used by a clever attacker with malicious intent to
cause a fork.
Test cases which exercise these conditions have been added to the
reference tests and will contributed upstream to improve the quality for
the entire ecosystem.
Unlike OP_IF and OP_NOTIF which interpret the top stack item as a
number, OP_IFDUP interprets it as a boolean. This has important
consequences because numbers are imited to int32s while booleans can be
an arbitrary number of bytes.
The offending script was found and reported by Jonas Nick through the
use of fuzzing.
The ScriptVerifyCleanStack flag requires that only a single
stack element remains after evaluation and that when interpreted
as a bool, it must be true. This is BIP0062, rule 6.
This mimics Bitcoin Core commit b6e03cc59208305681745ad06f2056ffe6690597
The ScriptVerifyMinimalData enforces that all push operations use the
minimal data push required. This is part of BIP0062.
This commit mimics Bitcoin Core commit
698c6abb25c1fbbc7fa4ba46b60e9f17d97332ef
This commit adds two new verification flags to txscript named
ScriptVerifyStrictEncoding and ScriptVerifyDerSignatures.
The ScriptVerifyStrictEncoding flag enforces signature scripts
and public keys to follow the strict encoding requirements.
The ScriptVerifyDerSignatures flag enforces signature scripts
to follow the strict encoding requirements.
These flags mimic Bitcoin Core's SCRIPT_VERIFY_STRICTENC and
SCRIPT_VERIFY_DERSIG flags and brings the Bitcoin Core test scripts up
to date.
This commit contains the entire btcscript repository along with several
changes needed to move all of the files into the txscript directory in
order to prepare it for merging. This does NOT update btcd or any of the
other packages to use the new location as that will be done separately.
- All import paths in the old btcscript test files have been changed to the
new location
- All references to btcscript as the package name have been chagned to
txscript
This is ongoing work toward #214.
