Publish PGP signed tarball without generated content?

[Simon Josefsson]

Hi

What do you think about publishing PGP signed tarballs without the
generated files such as the ./configure script?

What I'm looking for is for some private key holder of the OpenSSH
portable release key to run

git checkout V_9_7_P1
git archive --prefix=openssh-portable-V_9_7_P1/ -o openssh-9.7p1-src.tar.gz HEAD
gpg --detach-sign --armor openssh-9.7p1-src.tar.gz

and then publish the resulting openssh-9.7p1-src.tar.gz and
openssh-9.7p1-src.tar.gz.asc files, preferably using a version of git
that leads to archives that are identical to what GitHub currently
publish.

The tarball would then be identical to what can (currently) be
downloaded from the GitHub release page, thereby also allowing easy
auditing of both GitHub download links.

git clone https://github.com/openssh/openssh-portable.git openssh-github
cd openssh-github
git checkout V_9_7_P1
git archive --prefix=openssh-portable-V_9_7_P1/ -o openssh-9.7p1-src.tar.gz HEAD
wget -nv https://github.com/openssh/openssh-portable/archive/refs/tags/V_9_7_P1.tar.gz
sha256sum openssh-9.7p1-src.tar.gz V_9_7_P1.tar.gz
=>
f0c22a08eeaa7dfbae3ba553031a8c7d5322e498216d99ad8074a076b28c6f90  openssh-9.7p1-src.tar.gz
f0c22a08eeaa7dfbae3ba553031a8c7d5322e498216d99ad8074a076b28c6f90  V_9_7_P1.tar.gz

The advantage with all this is that people can then build from a tarball
that corresponds to what's in the git repository, and not have to audit
the generated ./configure script and other files, or have to manually
figure out which files needs to be removed from the official release
tarball to get something that corresponds to the git repository.

Building from a 'git clone' after verifying PGP signature of the
V_9_7_P1 git tag does not lead to the same level of assurance: 1) the
git tag can be moved and re-signed at any time but tarballs are forever,
2) git tags covers a SHA1 commit identity and SHA1 is broken so this
verification does not necessarily prove that the file content correspond
to what was intended to be released.  Any SHA-256 checksums of the git
tree is not part of the release announcements either, so it is not
possible to trace things back to the release information.  For more
discussion of rationale, see also:

https://blog.josefsson.org/2024/04/13/reproducible-and-minimal-source-only-tarballs/

/Simon
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