a27430e259
83950275edqa: unit test sighash caching (Antoine Poinsot)b221aa80a0qa: simple differential fuzzing for sighash with/without caching (Antoine Poinsot)92af9f74d7script: (optimization) introduce sighash midstate caching (Pieter Wuille)8f3ddb0bccscript: (refactor) prepare for introducing sighash midstate cache (Pieter Wuille)9014d4016atests: add sighash caching tests to feature_taproot (Pieter Wuille) Pull request description: This introduces a per-txin cache for sighash midstate computation to the script interpreter for legacy (bare), P2SH, P2WSH, and (as collateral effect, but not actually useful) P2WPKH. This reduces the impact of certain types of quadratic hashing attacks that use standard transactions. It is not known to improve the situation for attacks involving non-standard transaction attacks. The cache works by remembering for each of the 6 sighash modes a `(scriptCode, midstate)` tuple, which gives a midstate `CSHA256` object right before the appending of the sighash type itself (to permit all 256, rather than just the 6 ones that match the modes). The midstate is only reused if the `scriptCode` matches. This works because - within a single input - only the sighash type and the `scriptCode` affect the actual sighash used. The PR implements two different approaches: * The initial commits introduce the caching effect always, for both consensus and relay relation validation. Despite being primarily intended for improving the situation for standard transactions only, I chose this approach as the code paths are already largely common between the two, and this approach I believe involves fewer code changes than a more targetted approach, and furthermore, it should not hurt (it may even help common multisig cases slightly). * The final commit changes the behavior to only using the cache for non-consensus script validation. I'm open to feedback about whether adding this commit is worth it. Functional tests are included that construct contrived cases with many sighash types (standard and non-standard ones) and `OP_CODESEPARATOR`s in all script types (including P2TR, which isn't modified by this PR). ACKs for top commit: achow101: ACK83950275eddergoegge: Code review ACK83950275eddarosior: re-ACK83950275edTree-SHA512: 65ae8635429a4d563b19969bac8128038ac2cbe01d9c9946abd4cac3c0780974d1e8b9aae9bb83f414e5d247a59f4a18fef5b37d93ad59ed41b6f11c3fe05af4
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/license/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled during the generation of the build system) with: ctest. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.