Draft: draft-ietf-rats-architecture

Commentary: Also improve wording of watchdog use case 's discussion of TPMs . Signed - off - by :   
 This section , as put , is kind of a big leap , no ? I think the important part of this next level , is the introduction of a hardware root of trust like a TPM to eliminate the need to trust the device ’s operating system software in reporting attestation results . 
 How about " For strongest security , .... " to avoid confusion with high level OS . 
 This also already fixed by existing text . 
 If a TPM is the  environment , then in the case where this system had a TPM , this statement would not be true , no ? In other words , should n’t this example be restricted to attestation without a TPM ? ( I think you can say something like “ hardware root of trust for verification ” or something if we should avoid naming technologies ) In contrast , I think in a TPM system , the firmware initializes the Attesting Environment , the TPM is the attesting environment , and the same attesting environment is used by all layers . 
 For context ,  's comment was on the first sentence in this paragraph : My understanding is that a TPM requires another entity to feed it measurements which the TPM measures , the TPM does n't actively collect claims itself . Thus to me , the TPM is not the Attesting Environment . The Attesting Environment is the combination of the TPM + whatever is feeding it the measurements . Viewed that way , I believe the text is true as written . 
 Yes . We need text that captures that prominently and then also in that text start with " the composite of TPM & amp ; root of trust for measurement " forms an Attesting Environment instead of " he TPM is not the Attesting Environment " . Starting with the latter seems to produce reflexive and unnecessary knee - jerk reactions that we can also easily resolve , finally . Does that sound like a feasible approach ? 
 Yes I like that . 
 section : # # Two Types of Environments of an Attester now includes text : ~ What else do you want to say ? Why not ? What ’s the message you want to convey here ? What would disqualify an execution environment from being capable of claims collection ? How would you know if an Execution Environment is an Attesting Environment ? 
 What does it mean to be capable of claims collection ?
Paragraph (version A):
In the case, the Relying Party is the watchdog timer in the TPM/
secure enclave itself, as described in TCGarch section 43.3.  The
Attestation Results are returned to the device, and provided to the
enclave.
Paragraph (version A):
If the watchdog does not receive regular, and fresh, Attestation
Results as to the systems' health, then it forces a reboot.
Paragraph (version B):
A solution to this problem is a watchdog timer implemented in a
protected environment such as a Trusted Platform Module (TPM), as
described in TCGarch section 43.3.  If the watchdog does not receive
regular, and fresh, Attestation Results as to the system's health,
then it forces a reboot.
Paragraph (version B):
An arbitrary execution environment may not, by default, be capable of
claims collection for a given Target Environment.  Execution
environments that are designed specifically to be capable of claims
collection are referred to in this document as Attesting
Environments.  For example, a TPM doesn't actively collect claims
itself, it instead requires another component to feed various values
to the TPM.  Thus, an Attesting Environment in such a case would be
the combination of the TPM together with whatever component is
feeding it the measurements.