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58 lines
2.7 KiB
58 lines
2.7 KiB
3 years ago
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Tooling for verification of PGP signed commits
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----------------------------------------------
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This is an incomplete work in progress, but currently includes a pre-push hook
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script (`pre-push-hook.sh`) for maintainers to ensure that their own commits
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are PGP signed (nearly always merge commits), as well as a Python 3 script to verify
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commits against a trusted keys list.
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Using verify-commits.py safely
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------------------------------
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Remember that you can't use an untrusted script to verify itself. This means
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that checking out code, then running `verify-commits.py` against `HEAD` is
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_not_ safe, because the version of `verify-commits.py` that you just ran could
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be backdoored. Instead, you need to use a trusted version of verify-commits
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prior to checkout to make sure you're checking out only code signed by trusted
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keys:
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```sh
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git fetch origin && \
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./contrib/verify-commits/verify-commits.py origin/master && \
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git checkout origin/master
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```
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Note that the above isn't a good UI/UX yet, and needs significant improvements
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to make it more convenient and reduce the chance of errors; pull-reqs
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improving this process would be much appreciated.
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Configuration files
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-------------------
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* `trusted-git-root`: This file should contain a single git commit hash which is the first unsigned git commit (hence it is the "root of trust").
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* `trusted-sha512-root-commit`: This file should contain a single git commit hash which is the first commit without a SHA512 root commitment.
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* `trusted-keys`: This file should contain a \n-delimited list of all PGP fingerprints of authorized commit signers (primary, not subkeys).
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* `allow-revsig-commits`: This file should contain a \n-delimited list of git commit hashes. See next section for more info.
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Import trusted keys
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-------------------
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In order to check the commit signatures, you must add the trusted PGP keys to your machine. [GnuPG](https://gnupg.org/) may be used to import the trusted keys by running the following command:
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```sh
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gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys $(<contrib/verify-commits/trusted-keys)
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```
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Key expiry/revocation
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---------------------
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When a key (or subkey) which has signed old commits expires or is revoked,
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verify-commits will start failing to verify all commits which were signed by
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said key. In order to avoid bumping the root-of-trust `trusted-git-root`
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file, individual commits which were signed by such a key can be added to the
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`allow-revsig-commits` file. That way, the PGP signatures are still verified
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but no new commits can be signed by any expired/revoked key. To easily build a
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list of commits which need to be added, verify-commits.py can be edited to test
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each commit with BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG set to both 1 and 0, and
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those which need it set to 1 printed.
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