Verifying bpfcompat releases

Every tagged release of bpfcompat ships with a full supply-chain bundle so you can prove a binary came from this repository's build workflow before you run it:

Artifact	What it is
bpfcompat-linux-amd64, bpfcompat-validator-static-linux-amd64	the binaries
SHA256SUMS (+ .sig, .crt)	checksums, cosign-signed (keyless)
bpfcompat.sbom.cdx.json	CycloneDX SBOM
release-candidate-evidence.json	Tag, commit, workflow run, exact image digest, and positive/negative VM report hashes
SLSA provenance attestation	provenance bound to the artifact digest, repository, commit, and release workflow
SBOM attestation	the SBOM bound to the binary's digest

Signing is keyless (Sigstore Fulcio + Rekor) via GitHub Actions OIDC — there is no long-lived private key. The signer identity is the release workflow itself.

1. Verify build provenance (recommended)

Requires the GitHub CLI (gh). This is the strongest check — it proves the binary was built by this repo's release workflow:

gh attestation verify ./bpfcompat-linux-amd64 --repo Kernel-Guard/bpfcompat

A pass confirms the artifact's digest matches an attestation produced by the release-artifacts workflow on a v* tag. To pin the exact workflow identity:

gh attestation verify ./bpfcompat-linux-amd64 \
  --repo Kernel-Guard/bpfcompat \
  --signer-workflow Kernel-Guard/bpfcompat/.github/workflows/release-artifacts.yml

The promotion evidence is independently attested by the same workflow:

gh attestation verify ./release-candidate-evidence.json \
  --repo Kernel-Guard/bpfcompat \
  --signer-workflow Kernel-Guard/bpfcompat/.github/workflows/release-artifacts.yml

Offline / air-gapped verification is supported by downloading the attestation bundle first (gh attestation download) and verifying with --bundle.

2. Verify checksums + cosign signature

# 1) integrity
sha256sum -c SHA256SUMS

# 2) authenticity of SHA256SUMS (keyless cosign)
cosign verify-blob SHA256SUMS \
  --signature SHA256SUMS.sig \
  --certificate SHA256SUMS.crt \
  --certificate-identity-regexp '^https://github.com/Kernel-Guard/bpfcompat/.github/workflows/release-artifacts.yml@refs/tags/v' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com

3. Inspect the SBOM

# human-readable component list
cat bpfcompat.sbom.cdx.json | jq '.components[].name' | sort -u
# or verify the SBOM attestation is bound to the binary
gh attestation verify ./bpfcompat-linux-amd64 --repo Kernel-Guard/bpfcompat --predicate-type https://cyclonedx.org/bom

What this gives you

• Integrity — the bytes weren't altered (checksums).
• Authenticity — they were signed by this repo's workflow, not a fork or attacker (cosign cert identity).
• Provenance — a tamper-evident record of which commit and workflow built them.
• Promotion binding — one attested record connects the release tag and commit to the tested VM reports and promoted container digest.

The GitHub Action consumes prebuilt release binaries only after both sha256sum -c and gh attestation verify succeed for the CLI and validator. Attestation verification is restricted to .github/workflows/release-artifacts.yml; a checksum or attestation mismatch is a hard failure. When attestation verification is unavailable, the Action builds from its pinned source instead of trusting unverifiable release bytes.