Merge #12822: Revert 7deba93 and fix expired-key-sigs properly

9471576 [verify-commits] Add some additional useful documentation. (Matt Corallo)
de7e931 Add Marco-expired-key-signed-commits to allow-revsig-commits (Matt Corallo)
99f6d48 Revert "test: Update trust git root". (Matt Corallo)

Pull request description:

  7deba93 was took the wrong approach to updating verify-commits for a key expiration. Namely, adding each commit to allow-revsig-commits should have been done instead, allowing them to still be validated, but with the expired key.

Tree-SHA512: 9fdc67eda8f6daa95082f6c1a2af81beb730a9ff3f8cf930bb2311fe29b5f05e1f89259aba5f112153ca2e9c62577cf60d31b4c8e9ac1bf3f5506e78f8401378

Author: laanwj

contrib/verify-commits/README.md

@@ -24,3 +24,24 @@ keys:
 Note that the above isn't a good UI/UX yet, and needs significant improvements
 to make it more convenient and reduce the chance of errors; pull-reqs
 improving this process would be much appreciated.
+
+Configuration files
+-------------------
+
+* `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").
+* `trusted-sha512-root-commit`: This file should contain a single git commit hash which is the first commit without a SHA512 root commitment.
+* `trusted-keys`: This file should contain a \n-delimited list of all PGP fingerprints of authorized commit signers (primary, not subkeys).
+* `allow-revsig-commits`: This file should contain a \n-delimited list of git commit hashes. See next section for more info.
+
+Key expiry/revocation
+---------------------
+
+When a key (or subkey) which has signed old commits expires or is revoked,
+verify-commits will start failing to verify all commits which were signed by
+said key. In order to avoid bumping the root-of-trust `trusted-git-root`
+file, individual commits which were signed by such a key can be added to the
+`allow-revsig-commits` file. That way, the PGP signatures are still verified
+but no new commits can be signed by any expired/revoked key. To easily build a
+list of commits which need to be added, verify-commits.sh can be edited to test
+each commit with BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG set to both 1 and 0, and
+those which need it set to 1 printed.