1. Remote ATtestation ProcedureS (RATS)
IETF 103, November 6, Bangkok
Henk Birkholz
Ned Smith
Monty Wiseman
Eric Voit

2. Trends in Trust
Hosts
Communications
100
% Trusted
1970’s
1990’s
Today

3. Problem  Need Problem Need
Desire to understand host characteristics of peers to prevent communications with peers of compromised integrity
But the integrity of assertions about host characteristics cannot be assured with software-based approaches alone (e.g. Network Endpoint Assessment)
Need
Assertions about characteristics of peers anchored in hardware roots of trust
Means to convey assertions in a timely and secure fashion

4. Host Characteristics Hosts  System Components [RFC4949]
Host Characteristics = Assertions [ITU X.1252] that can be signed

5. Root of Trust (RoT) NIST SP 800-164
“Security primitives composed of hardware, firmware and/or software that provide a set of trusted, security-critical functions. They must always behave in an expected manner because their misbehavior cannot be detected. As such, RoTs need to be secured by their design”
“Trusting” a Root of Trust is a decision made by the relying party.

6. Conveyance of Assertions
Network Protocols have to address requirements for secure conveyance of assertions
Message Formats (e.g. data models) have to address requirements for secure conveyance of assertions
Definition of the demarcation line is part of the work
Some requirements:
Freshness
Integrity
Confidentiality
Privacy

7. The General Model for Remote Attestation (in ASCII Art)

8. Proposed Remote Attestation Model
Attribute cert provisioned by device vendor
Device manufacturer
ROT manufacturer
Private key and X.509 certificate provisioned by ROT manufacture
Obtain CA certificates to chain up attestation & attribute certs to trusted roots.
Device
Lots of assertions about ROT
Nonce
ROT
Lots of signed assertions about Device
Att Key
Relying Party / Verifier
Measurements
Remote Attestation
Nonce
Assertions…
Signed Assertions…
Signature
Signature and public key verification process
Lots of assertions + verification of multiple signatures
Risk engine
Evidence creation & signing
Private keys for signing. Stored securely on ROT.