Use Trivy for the bill of materials and cosign to sign releases

How to do it

The Trivy you already run for scans also writes SPDX and CycloneDX files, so the bill needs no new tool. cosign 1.0 came out on 28 July 2021, and 3.1.4 shipped on 20 October 2026. It belongs to Sigstore, an OpenSSF project, and its repository had about 6,400 stars in October 2026. Keyless signing uses the CI job's identity, so no private key can leak. Each signature goes into Sigstore's public log, which shows the repository name. Private projects sign with a key held in their secrets store instead. Pin cosign by digest, as the Trivy rule does. What to publish is in Publish what is in each release. Verify before each deploy, as Build releases only in CI and verify them before deploy says. Choose something else when your registry already signs with Notation from the Notary Project, and keep one signer for every image.

Examples

Shell example

IMAGE=registry.example.com/shop@sha256:0000000000000000000000000000000000000000000000000000000000000000
trivy image --format cyclonedx --output sbom.cdx.json "$IMAGE"
cosign sign --yes "$IMAGE"
cosign attest --yes --type cyclonedx --predicate sbom.cdx.json "$IMAGE"

Shell example 2

cosign verify \
  --certificate-identity-regexp '^https://github.com/example/shop/' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  "$IMAGE"

How to check

Each release image has a CycloneDX attestation. cosign verify with the expected CI identity passes, and it fails for an image pushed from a laptop.

Sources

• Trivy SBOM
• Sigstore
• SLSA specification

Related rules

• Make release tags and files immutable in Engineering
• Use Trivy to scan images and dependencies in Software choices
• Publish what is in each release in Security testing
• Build releases only in CI and verify them before deploy in Engineering