Verifying releases

Release artifacts are keyless-signed (cosign) and carry a SLSA build-provenance attestation. Each release also ships a CycloneDX SBOM of Scratchsmith's own dependency graph. That file is scratchsmith-v<ver>.cdx.json, and it is listed in checksums.txt, so the signature and provenance cover it too. It reflects the full Cargo.lock graph, so it includes build- and dev-dependencies, not only the crates that link into the shipped binary.

The release also carries scratchsmith.intoto.jsonl, the SLSA provenance bundle. You do not need to download it, because gh attestation verify reads the attestation from GitHub.

Replace <ver> with the bare version you downloaded, no leading v (the tarball adds the v prefix, but the image tag does not).

# SLSA provenance — the simplest, ref-agnostic check
gh attestation verify scratchsmith-v<ver>-linux-amd64.tar.gz --repo schubydoo/scratchsmith

# Checksums signature (one cosign signature covers every tarball through its hash)
cosign verify-blob checksums.txt \
  --bundle checksums.txt.sigstore.json \
  --certificate-identity-regexp '^https://github\.com/schubydoo/scratchsmith/\.github/workflows/knope-release\.yml@' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com
sha256sum -c checksums.txt        # then check the tarball + SBOM hashes

# The signed GHCR image
cosign verify ghcr.io/schubydoo/scratchsmith:<ver> \
  --certificate-identity-regexp '^https://github\.com/schubydoo/scratchsmith/\.github/workflows/release\.yml@refs/tags/' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com

Signing the image pack produces

The commands above verify Scratchsmith's own release artifacts. To sign an image Scratchsmith builds for you, pack --push --sign cosign-signs the pushed image by digest (keyless), and --sbom --sign attaches the SBOM as a signed attestation. Both only apply to the registry-push sink, since cosign signs a registry image. See Usage.