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Verifying SLSA Build Provenance for Raven Container Images ​

Every container image published by this repository to GHCR carries two cryptographic attestations:

  • SLSA v1 build provenance — who built the image, from which commit, on which workflow, at what time.
  • SPDX SBOM — the full software bill of materials for the image.

Both are signed keylessly via Sigstore using GitHub OIDC and anchored in the public Rekor transparency log. Attestations are stored both in the GitHub attestation store and as OCI referrers alongside the image in GHCR.

Images covered: ghcr.io/ravencloak-org/{go-api,python-worker,frontend}. Attestations exist for every image pushed from main or a v*.*.* tag on or after the commit that landed this feature.

Verify with gh (GitHub CLI) ​

Primary path — no extra install beyond gh.

Provenance:

bash
gh attestation verify \
  oci://ghcr.io/ravencloak-org/go-api:latest \
  --owner ravencloak-org \
  --predicate-type https://slsa.dev/provenance/v1

SBOM:

bash
gh attestation verify \
  oci://ghcr.io/ravencloak-org/go-api:latest \
  --owner ravencloak-org \
  --predicate-type https://spdx.dev/Document/v2.3

Substitute go-api with python-worker or frontend for the other two images, and replace latest with any tag or sha256: digest you want to verify.

Verify with cosign ​

For environments without gh:

Provenance:

bash
cosign verify-attestation \
  --type slsaprovenance1 \
  --certificate-identity-regexp \
    'https://github.com/ravencloak-org/Raven/.github/workflows/(docker|release)\.yml@.*' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  ghcr.io/ravencloak-org/go-api:latest

SBOM:

bash
cosign verify-attestation \
  --type spdxjson \
  --certificate-identity-regexp \
    'https://github.com/ravencloak-org/Raven/.github/workflows/(docker|release)\.yml@.*' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  ghcr.io/ravencloak-org/go-api:latest

Always Verify by Digest in Production ​

Tags like :latest are mutable. For any real supply-chain check, pin to the image's immutable sha256: digest. Resolve a tag to a digest with either of:

bash
crane digest ghcr.io/ravencloak-org/go-api:latest
bash
docker buildx imagetools inspect ghcr.io/ravencloak-org/go-api:latest --format '{{json .Manifest.Digest}}'

Then verify the digest directly:

bash
gh attestation verify \
  oci://ghcr.io/ravencloak-org/go-api@sha256:<digest> \
  --owner ravencloak-org \
  --predicate-type https://slsa.dev/provenance/v1

cosign verify-attestation accepts the same <image>@sha256:<digest> form.

What Verification Proves ​

  • The image was built from ravencloak-org/Raven by either the docker.yml workflow (main-branch pushes) or the release.yml workflow (tag releases), on a GitHub-hosted runner.
  • The commit SHA in the provenance matches a real commit on this repo.
  • The image digest you pull is byte-for-byte the one that was attested.
  • The SBOM was produced by the same build.

What Verification Does NOT Prove ​

  • That the image is free of known vulnerabilities — that is what Trivy and govulncheck in .github/workflows/security.yml cover.
  • That the build is bit-for-bit reproducible.
  • Runtime integrity. Attestation is a build-time guarantee.

Notes ​

  • actions/attest-sbom@v3 supports SPDX only; the SBOM attestation uses spdx-json. A CycloneDX variant is not produced.
  • If you verify an image pushed before this feature landed (PR #352), both commands will fail with "no attestation found". That is expected.
  • If gh attestation verify fails with an auth error, run gh auth login and ensure the account has read access to ravencloak-org/Raven.
  • Re-pushing an image with an unchanged digest will add a new referrer manifest rather than dedupe. gh attestation verify picks the first valid attestation, so this is benign.
  • The SBOM is attached to the multi-arch manifest-list digest, so a single SBOM covers all platforms for a given tag. Syft runs against one platform when generating it, so platform-specific contents (e.g. arm64 vs. amd64 system libs) may not be fully enumerated. Per-platform SBOM attestation is a tracked follow-up.

References ​