Re: [Pqc] [TLS] Did TLS AuthKEM die?

[John Mattsson <[e-mail]>]

Using ephemeral-static ECDH for implit authentication as in the Noise protocol has several benefits. The benefits of using KEMs instead of signatures seem more limited. The current proposal requires 3 full round-trips instead of 1.5 round-trips for mutual authentication. If I understand correctly, the messages sizes are smaller than Kyber+Dilithium but similar to Kyber+Falcon (probably a bit larger in total).

If continued, I think Kyber KEMs makes a lot more sense than ECDH KEM. For ECDH KEM you can do something much more efficient.

Two comments on the document

- “these proposals require a non-interactive key exchange”
My understandaing of NIKE is that the parties do not have any interaction. One example of NIKE is static-static DH. OPTLS uses ephemeral-static DH. I don't think it is correct to describe that as NIKE.
https://eprint.iacr.org/2012/732.pdf

- The document could mentioned that to derive the application_traffic_secret, an attacker needs more than a single private key. Having a single ephemeral private key is no longer enough as it is the case in ordinary certificate based TLS 1.3.

Cheers,
John


From: TLS <[e-mail]> on behalf of Blumenthal, Uri - 0553 - MITLL <[e-mail]>
Date: Tuesday, 24 January 2023 at 19:15
To: Mike Ounsworth <Mike.Ounsworth=[e-mail]>, [e-mail] <[e-mail]>, [e-mail] <[e-mail]>
Subject: Re: [TLS] Did TLS AuthKEM die?
I truly hope AuthKEM is alive.

--
V/R,
Uri

There are two ways to design a system. One is to make it so simple there are obviously no deficiencies.
The other is to make it so complex there are no obvious deficiencies.
                                                                                                                                     -  C. A. R. Hoare


From: TLS <[e-mail]> on behalf of Mike Ounsworth <Mike.Ounsworth=[e-mail]>
Date: Tuesday, January 24, 2023 at 12:33
To: "[e-mail]" <[e-mail]>, "[e-mail]" <[e-mail]>
Subject: [TLS] Did TLS AuthKEM die?

Thom, Sofía,

draft-celi-wiggers-tls-authkem is expired. Is that on purpose? Does it still have steam or is it dead?

---
Mike Ounsworth
Software Security Architect, Entrust

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