[Rats] Re: Call for adoption: draft-deshpande-rats-multi-verifier-04 (Ends 2026-04-24)

[Yogesh Deshpande <[e-mail]>]

Dear Usama,

There is a clear statement in the Privacy section:

“However, when carefully designed, a multi-verifier architecture can actually mitigate these privacy concerns. By distributing appraisal responsibilities and ensuring that no single Verifier has access to the full set of Evidence, the risk of comprehensive device profiling or tracking is reduced.”

This is exactly the statement, which substantiates the arguments presented below.

Regards,
Yogesh

From: Muhammad Usama Sardar <[e-mail]>
Sent: Thursday, April 23, 2026 9:37 AM
To: Thomas Fossati <[e-mail]>
Cc: Simon Frost <[e-mail]>; [e-mail]; [e-mail]; Manu Fontaine <[e-mail]>; [e-mail]
Subject: Re: [Rats] Re: Call for adoption: draft-deshpande-rats-multi-verifier-04 (Ends 2026-04-24)


Hi Thomas,
On 23.04.26 10:13, Thomas Fossati wrote:

On Thu, 23 Apr 2026 at 00:47, Manu Fontaine <[e-mail]><mailto:[e-mail]> wrote:



We also strongly share Usama's security and privacy concerns, which amplify with each additional independent system. We wish RATS approached the problem from the relying party's perspective.



A decrease in privacy is not inevitable.

In fact, a multi-verifier arrangement could increase overall privacy

compared to a monolithic one.

The key is to make evidence opaque to the lead verifier, so that it

only dispatches component evidence to the "downstream" verifiers and

collects the associated results.

In this way, only the verifier trusted by the attester sees the PIIs;

the system avoids the panopticon effect present in a monolithic

approach.

I would like to note that the call for adoption is of -04 which has no such mechanism. -04 substantially increases the privacy problems. In addition to revealing the PII to the lead verifier (which say is kind of equivalent to monolithic verifier), it reveals the PII to all those Component Verifiers as well.

Instead of acknowledging this substantial technical flaw in the design, Privacy Considerations are misleading the readers to believe on the contrary [0]. This is disservice to the community.

[...] (we sort of disagree with the sentence: "The Verifier is not part of the Attester’s Trusted Computing Base").



I don't know if you have a specific system in mind, but, in general,

the Verifier is part of the RP's TCB, not the Attester's.

This is another misleading statement in the draft. What's important here is the TCB of RP and not the Attester. It is the RP who has to make final decision, and not the Attester. Verifier is -- in any case -- in the TCB of RP.

Best,

-Usama


[0] https://www.ietf.org/archive/id/draft-deshpande-rats-multi-verifier-04.html#section-8-2

IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.