stacklok / toolhive / 30342035384

push

github

Add Sigstore signer package for skill OCI artifacts (#6023)

* Add Sigstore signer package for skill OCI artifacts

Skills pushed to OCI registries need signatures so installs can be
verified against the lock file's recorded provenance (RFC THV-0080).
This adds pkg/skills/signer: cosign key-pair signing that signs the
simple-signing payload (binding the artifact's manifest digest), pushes
the classic cosign signature manifest at the sha256-<hex>.sig tag for
interop with `cosign verify --key`, and returns the serialized Sigstore
bundle for durable storage and offline re-verification.

The signature is computed once over the payload and reused for both the
registry manifest annotation and the returned bundle, so a verifier
reconstructing the bundle from the registry checks exactly the
signature that was attached. Encrypted keys are decrypted via
COSIGN_PASSWORD, matching the cosign CLI. Key paths are canonicalized
(absolute, symlinks resolved, regular-file check) before opening.

Part of #5899; consumed by the push-signing and install-verification
PRs in this stack.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Extend signer tests to error paths and keypair metadata

Cover input-validation failures (garbage key, bad reference, malformed
digest), bare-hex digest normalization, the payload's digest/repository
binding, and the sigstore Keypair metadata accessors, raising patch
coverage flagged by codecov.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

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Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

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