Hi Usama,
Thanks for your response, please see my in-line replies with [WW].
The latest version of this draft is attached. Thank you!
Best Regards,
Wei
Original
From: Muhammad Usama Sardar <[email protected]>
Date: 2026-04-13 02:10
To: Wei Wang <[email protected]>, Aijun Wang
<[email protected]>
Cc: tls <[email protected]>, draft-wang-tls-service-affinity
<[email protected]>, Mohit Sahni
<[email protected]>
Subject: [TLS] Comments on draft-wang-tls-service-affinity (was Montreal ...)
Hi Wei,
Following up with a suggestion on how to proceed:
At a high level, I think it may be helpful to take a step back and
approach this from a security-first perspective rather than a
design-first perspective. I understand this sounds like moving back
to zero, but if you want me to help you, we need to move more logically
and it might really help. However, I want to be clear that the final
design may come out to be completely different from what you have.
[WW]: Our original intention in proposing this technical solution is to address
business issues and, on that basis, examine whether any new security problems
have arisen. It does not focus on security issues, so I think a design-first
perspective is more suitable.
Of course, this is just a suggestion and as author of draft, you have the
choice -- please feel free to take or leave it. If you would prefer a
different direction, I kindly ask you to just let me know so I can plan
accordingly.
Is it implemented somewhere? If yes, do they have anything public on how
it is implemented? That would be really helpful for me.
On 09.04.26 11:50, Muhammad Usama Sardar wrote:
On 09.04.26 08:10, Wei Wang wrote:
The protocol design in section 4 has been revised based on TLS 1.3.
I am not sure if this one has been fully addressed. As an example,
please note that you still have 4xChangeCipherSpec messages in Figure 1
while this message seems to have been removed in TLS 1.3, "except when
needed for middlebox compatibility" [0]. There seems to be no
explanation in your draft why you need this message. Please explain
this in the text.
So based on [2], please remove 4xChangeCipherSpec from the handshake.
Before proceeding with the design, I propose to first focus on the threat
model and security goals (see below) to help me understand what you want to
achieve.
[WW]: Done.
Since we are not very familiar with security-related
technologies, would you like to help us improve the content of
security considerations?
Yes, with great pleasure. I am currently stuck in another high-stake
issue. When I get some time, I will update my draft [3] to explain this
and then come back to you.
I've added some details, examples and reference in Sec. 5.2 and 5.3
[4,5]. Please check it out and let me know if it helps you. If it is
not helpful, please do not hesitate to let me know what you find
difficult, and I will be happy to add more details. You could start with
very high-level requirements and ignore the unless conditions in the
first stage etc. Like, think about what is it that you want to protect
and what does protect mean (integrity, freshness, etc.).
One thing I am missing in the draft is the threat model. I would like to
see clear independent subsections (see my proposed document format in
draft-usama-tls-fatt-extension) on the threat model and security goals
that you want to achieve.
Security goals must be independent of your current design, like after
reading the "Introduction" and "Motivation and Design Rationale"
sections, I should be able to jump over directly to the section on threat
model and security goals. Can you try it based on [4] and [5]? and then
we can work together to improve it.
What do you think? Are you open to this approach?
[WW]: Thank you for the detailed explanation and the references.
I find drafting the Threat Model quite challenging, but I have attempted to
list some Informal Security Goals in Section 7.2. Could you please review them
and help us further refine the content of both Section 7.1 and Section 7.2
based on this?
Best wishes,
-Usama
[0]
https://www.ietf.org/archive/id/draft-ietf-tls-rfc8446bis-14.html#section-1.3-2.6.1
[1] https://www.ietf.org/archive/id/draft-ietf-tls-rfc8446bis-14.html
[2] https://github.com/tlswg/tls13-spec/issues/1413
[3]
https://www.ietf.org/archive/id/draft-usama-tls-fatt-extension-02.html#section-4.3
[4]
https://www.ietf.org/archive/id/draft-usama-tls-fatt-extension-03.html#section-5.2
[5]
https://www.ietf.org/archive/id/draft-usama-tls-fatt-extension-03.html#section-5.3
draft-wang-tls-service-affinity-02.pdf
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draft-wang-tls-service-affinity-02.xml
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