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author | Wolfgang Müller | 2021-05-22 13:22:34 +0200 |
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committer | Wolfgang Müller | 2021-05-22 13:22:34 +0200 |
commit | 0da8a6e3d85a98e38b1abc2499f7e7b3fe5d9534 (patch) | |
tree | ef5f061ddaecc6dee62a740ec7de297c5491fcf0 /posts | |
parent | 7d3a8b42587ba51c6f5c738d1c4c35cb7d405e20 (diff) | |
download | site-0da8a6e3d85a98e38b1abc2499f7e7b3fe5d9534.tar.gz |
posts: Add guide to verify a commit from a tarball
When generating archives, git-archive(1) puts the commit ID in the
global extended pax header. Therefore, an interesting side effect of
signing tarballs generated with git-archive(1) is that we also
implicitly sign a commit. Whilst we don't expect anyone to go through
the hurdles needed to verify such a commit signature, make sure to
document this case anyway.
Diffstat (limited to '')
-rw-r--r-- | posts/verify-with-signify.md | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/posts/verify-with-signify.md b/posts/verify-with-signify.md index 5103ccc..0fd22c4 100644 --- a/posts/verify-with-signify.md +++ b/posts/verify-with-signify.md @@ -56,4 +56,30 @@ the `sha256sum` tool to only verify the integrity of the download: $ tail -n1 <snapshot>.asc | sha256sum -c <snapshot>: OK +### Verification of the corresponding commit + +Every tarball hosted here contains its corresponding commit ID in the global +extended pax header[^2]. Therefore, if a tarball is signed, it may be used to verify +a commit and all of its ancestors. + +To do so, place the tarball in the cloned git repository first. If you already +have the detached signature, you may verify the tarball normally like shown +above. Otherwise, you can fetch the signatures directly from the repository: + + $ git fetch origin refs/notes/signatures/tar.gz:refs/notes/signatures/tar.gz + +Now you can verify the tarball like so: + + $ git notes --ref=signatures/tar.gz show <version> | signify -Cp release.pub -x - + Signature Verified + <snapshot>: OK + +Once verified, you can extract the commit using +[`git-get-tar-commit-id(1)`](https://git-scm.com/docs/git-get-tar-commit-id) and +show it: + + $ gzip -d -c <snapshot> | git get-tar-commit-id | xargs git show + [^1]: If you are interested in how this is put together, check out [this](signify-cgit) post. +[^2]: [`git-archive(1)`](https://git-scm.com/docs/git-archive#_description) puts + it there. |