Lesson 3.1 · 15 min read
RATS roles and artifacts (RFC 9334)
Attester, Verifier, Relying Party, Endorser and Reference Value Provider, and what each one produces.
A shared vocabulary
The IETF Remote ATtestation procedureS (RATS) working group published RFC 9334, the RATS architecture, in January 2023. It gives vendor-neutral names to the parties and messages in any attestation system. Using these terms in policies and audit reports avoids ambiguity, because each vendor otherwise has its own words for the same things.
| Role | What it does | Example |
|---|---|---|
| Attester | Produces Evidence about itself | An SEV-SNP guest returning a signed report; a Nitro Enclave returning an attestation document |
| Verifier | Appraises Evidence and produces Attestation Results | Microsoft Azure Attestation; Google Cloud Attestation; your own verification service |
| Relying Party | Uses Attestation Results to make a decision | A KMS that releases a key; a client deciding whether to send data |
| Endorser | Vouches for the Attester's hardware or firmware, via Endorsements | A CPU vendor's certificate chain and TCB information |
| Reference Value Provider | Supplies the known-good measurements, via Reference Values | Your CI pipeline publishing expected PCRs or launch digests |
| Verifier Owner / Relying Party Owner | Configure the Appraisal Policy for Evidence and for Attestation Results | The security team that approves which builds may receive secrets |
Key takeaways
- Evidence comes from the Attester; Attestation Results come from the Verifier. Do not confuse them.
- Endorsements (from the vendor) and Reference Values (from you) are separate inputs to appraisal.
- Someone must own the appraisal policy; in an audit, ask who that is and how changes are approved.