Verify a cosign attestation on a container image with cosign verify-attestation
domain: slsa.dev · 6 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Install cosign from the sigstore/cosign GitHub releases for your platform
Run cosign verify-attestation <image-ref> --type <predicate-type> to fetch and verify the attestation
For SLSA provenance, set --type to slsaprovenance or slsaprovenance02 depending on the predicate version used when the attestation was generated
Pass --certificate-identity and --certificate-oidc-issuer (or their regex equivalents) to enforce that the signing identity matches the expected GitHub Actions workflow
Pipe the output to jq or a policy engine to extract and evaluate specific fields from the verified predicate payload
Use --policy with a CUE or Rego policy file to automate assertion of predicate field values
Known gotchas
cosign verify-attestation fetches attestations stored in the OCI registry as sigstore bundles; if the attestation was stored elsewhere, you need to pass it differently
The --type flag must match the predicate type URI used at signing time; a mismatch causes the tool to report no matching attestations found
Keyless verification (Sigstore Fulcio + Rekor) requires that the signing OIDC token claims match the --certificate-identity flags; overly broad regexes can undermine the security check
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