Supply Chain Attestation

Every build artifact, from source code commits to container images, is signed with a private key managed in a Hardware Security Module (HSM). This creates a tamper-evident seal. The signature is stored in a public transparency log, allowing any consumer to verify the artifact's origin and integrity independently. This process leverages frameworks like Sigstore and Cosign to enable keyless signing tied to OpenID Connect identities.

Attestation requires that builds are bit-for-bit reproducible. Given the same source code and build environment, an independent party must be able to generate an identical artifact. This proves that no malicious code was injected during compilation. The attestation record includes a cryptographic hash of the build environment, inputs, and outputs, making any deviation from the declared build process immediately detectable.

An SBOM is a formal, machine-readable inventory of all components, libraries, and dependencies that make up a software artifact. Attestation binds the SBOM to the artifact via a signed in-toto attestation predicate. This allows automated policy engines to check for known vulnerabilities (CVEs) or prohibited licenses before deployment, ensuring compliance with Executive Order 14028 and SLSA frameworks.

The highest assurance level of attestation anchors trust in hardware. Build steps are executed inside a Trusted Execution Environment (TEE) like Intel SGX or AMD SEV. The TEE generates a hardware-signed attestation report proving the exact code that ran. This eliminates reliance on the security of a CI/CD platform's infrastructure, as the hardware itself vouches for the computational integrity of the build process.

Attestation data is not merely observational; it is actionable. Policy engines like Open Policy Agent (OPA) or Kyverno continuously evaluate attestation metadata against organizational policies. A deployment gate will automatically block an artifact from reaching production if its attestation is missing, its SBOM contains a critical vulnerability, or its build was not executed in a trusted environment, enforcing a zero-trust deployment pipeline.

All attestation metadata is published to an append-only, cryptographically verifiable transparency log (e.g., Rekor). This creates an immutable audit trail. Security teams can set up continuous monitoring to detect anomalies, such as an artifact being signed by a key that was not previously authorized, or a build occurring outside of normal hours, providing real-time detection of supply chain compromises.

A deployment-time control mechanism that ensures only artifacts with valid, policy-compliant attestations are admitted into production environments. Binary authorization platforms continuously verify:

• The artifact's signature against a trusted authority
• The attestation's claims against organizational policy (e.g., 'built from an approved repo')
• The freshness and non-revocation of the signing identity This acts as the enforcement point for supply chain attestation, blocking non-conforming deployments before they reach runtime.