Restructure storage so gittuf verification can run over backends other
than the git binary (e.g. go-git):
- pkg/githash: concrete Git object hash, stdlib-only.
gitinterface.Hash aliases it.
- pkg/gitstore: the single Storer interface (24 methods) that all
storage consumers program against, plus the shared
ErrReferenceNotFound sentinel. *gitinterface.Repository satisfies it
structurally (compile-time asserted). Also defines ConfigKey, the
canonical type for the Git config settings gittuf reads.
- pkg/rsl (from internal/rsl): entry model, codec, and readers over
gitstore.Storer; zero gitinterface/sigstore dependencies. rsl.Hash
aliases githash.Hash; nil is the unset-Hash sentinel and IsZero
matches nil and empty as well as both format zeros (no
object-format-unaware ZeroHash). Entry commits (empty tree on the
RSL ref) are owned by the package; no storer adapter.
- internal/signerverifier/gitobject: verifies commit/tag signatures
over (payload, signature) bytes, Rekor URL as an option. The storage
half is Repository.GetObjectSignature. Removes sigstore, cosign, and
gitsign from gitinterface's dependency tree.
- internal/propagation: propagation workflow, moved off pkg/rsl's
public API (its tuf directive types are internal).
- internal/{attestations,cache,policy}: storage via gitstore.Storer;
tree writing via WriteTree(blobs, subtrees).
Breaking changes to pkg/gitinterface: Repository.VerifySignature and
the verification sentinels are removed (use gitobject.Verify);
ErrReferenceNotFound now aliases gitstore's. Repository.GetGitConfig
(which returned the whole config map) is replaced by
LookupConfig(gitstore.ConfigKey), returning a single setting's value.
Policy resolves the Rekor override from git config once per
verification and extracts signed payloads once per object instead of
per key attempt.
Assisted-by: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Paulo Gomes <paulo@entire.io>
