Explainer · 4 min read

Hardware-attested
AI energy.

Three trust postures live on every certificate. hardware_attested is the top tier — and it is earned, not asserted. A certificate cannot claim this posture; it can only carry the evidence that proves it.

The three postures

• self_reported — the operator declared the value. Honest, but uncorroborated.
• cross_checked — at least two independent sensors agree on the measurement (e.g. NVML × RAPL passes the cross-validator), or solo dual_source evidence is present.
• hardware_attested — three or more evidence flags are present and cross-validation passed. Trust score ≥ 0.80.

What it takes to reach the top tier

A certificate is promoted to hardware_attested only when its trust score (0.0 – 1.0) reaches 0.80. The score is the sum of evidence weights:

The realistic enterprise configuration without a TEE — dual-source + signed exporter + machine fingerprint — lands at exactly 0.80. The TEE pushes it to 1.00. Posture is upgrade-only: a certificate never silently degrades; it either keeps its tier or moves up.

The five evidence sources

• NVML telemetry — GPU energy and power from the driver, sampled sub-second.
• RAPL telemetry — CPU package + DRAM domain energy from the kernel's powercap interface.
• Signed exporter — a sidecar that Ed25519-signs every /metrics response, with the public key registered per-tenant and revocable.
• Machine fingerprint binding — the exporter exposes a machine_id label and the backend checks it matches the agent's stable host fingerprint.
• TEE attestation — an optional SGX / SEV-SNP / Nitro quote proving the exporter runs inside a trusted enclave.

Why this tier exists

Auditors, regulators and counterparties need to know the difference between a number an operator says is true and a number a chain of independent sensors agrees is true. The trust posture string is the structured answer to that question, and hardware_attested is its strongest assertion — the only one Serial Alice will let a certificate carry when the math actually supports it.