Zero Trust Supply Chain

Every entity in the pipeline—whether a human developer, a CI/CD runner, or an automated bot—must be authenticated and authorized for each discrete action. This moves beyond static, perimeter-based credentials to short-lived, ephemeral tokens tied to workload identity.

• Workload Identity: Assigns verifiable, short-lived identities to non-human processes (e.g., a build service) using OpenID Connect, eliminating long-lived API keys.
• Ephemeral Credentials: Tokens that expire in minutes, not months, drastically reducing the blast radius of a leaked secret.
• Just-in-Time Access: Grants elevated permissions only when a specific task requires them and revokes them immediately afterward.

A Zero Trust pipeline requires a tamper-proof, verifiable record of every action performed on an artifact. Frameworks like in-toto cryptographically sign each step—from code checkout to compilation to containerization—creating an unbroken chain of custody.

• Non-Repudiation: A signed attestation proves definitively that a specific identity performed a specific action at a specific time.
• Policy Verification: Before deployment, an Open Policy Agent (OPA) can verify that all required attestations exist and are valid.
• Transparency Logs: Append-only ledgers like Rekor record signatures, making any attempt to backdate or forge an attestation publicly detectable.

Artifacts are treated as immutable objects that are never patched or modified in place. Any change, no matter how minor, triggers a completely new build with a unique cryptographic hash. This ensures that what was tested is exactly what is deployed.

• Content-Addressable Storage: Artifacts are identified by their SHA-256 digest, not a mutable tag like latest.
• Reproducible Builds: A deterministic compilation process allows independent parties to recreate a bit-for-bit identical artifact, proving no tampering occurred during the build.
• Binary Authorization: Deploy-time enforcement that rejects any container image lacking a valid cryptographic signature from a trusted authority.

No third-party dependency is trusted by default. Every open-source library, base image, and external module must be explicitly declared, verified, and continuously monitored. This directly combats dependency confusion and typosquatting attacks.

• Software Bill of Materials (SBOM): A machine-readable inventory like SPDX or CycloneDX that lists every component, enabling precise vulnerability mapping.
• Dependency Pinning: Locking dependencies to exact, immutable versions or cryptographic hashes to guarantee reproducible builds.
• Vulnerability Exploitability eXchange (VEX): Allows a supplier to declare the exploitability status of a specific vulnerability in their product, reducing false-positive noise from scanners.

Security and compliance rules are written as versioned, executable code that automatically gates progression between pipeline stages. A build that fails any policy check—such as a critical vulnerability in an SBOM or a missing attestation—is blocked from promotion.

• Open Policy Agent (OPA): A general-purpose policy engine that decouples decision-making from application logic, providing a unified framework for authorization.
• SLSA Framework: Supply-chain Levels for Software Artifacts provides a graded checklist (Level 1-4) of controls to prevent tampering and improve integrity.
• Automated Remediation: Policy violations trigger immediate notifications and can automatically roll back deployments or revoke access.

Verification does not stop at deployment. The Zero Trust model requires continuous monitoring of the running artifact's integrity against its attested baseline. Any drift between the expected and actual state triggers an alert or automatic termination.

• File Integrity Monitoring (FIM): Detects unauthorized changes to critical system files and binaries in running containers.
• In-Memory Attestation: Hardware-backed Trusted Execution Environments (TEEs) can provide cryptographic proof that the code loaded into memory matches the signed artifact.
• Drift Detection: Automated reconciliation loops compare the live state against the Git repository's declared desired state, a core tenet of GitOps.