On Thu, 19 Feb 2026 at 15:38, Neil Madden <[email protected]> wrote:

> I think it’s mostly fine. Some questions though:
>
> * Why support non-hybrids at all?
>

Non-hybrid key-exchange is only for compliance and regulatory purposes (it
is discussed in Section 1 of the draft). For instance, CNSA 2.0 defines use
of PQC algorithms only.


> * Why support ML-KEM-512 at all? Especially non-hybrid.
>

  ML-KEM-512 is primarily intended for constrained devices and
bandwidth-sensitive environments.  ML-KEM-512 is also supported by other
protocols like TLS and IPSec.


> * Why support P-256 at all? X25519 is a better choice, and P-384 is there
> for anyone still hampered by an irrational government.
>

P-256 is already added to the JOSE/COSE HPKE drafts. P-256 remains widely
deployed across TLS, IPsec, JOSE/COSE, and FIPS-validated modules.


>
> I’m also raising my eyebrows a bit at the ChaPoly variants. The usual
> rationale for ChaPoly over AES is that it’s fast and
> timing-channel-resistant on hardware that lacks AES acceleration. But are
> people really going to be running PQ hybrids on such low end hardware?
> That’s a huge code size to be pulling in at the least, not to mention
> memory pressure and energy draw. I’ll defer to the COSE people here on
> what’s likely in this space, but it feels a bit like filler rather than
> something that meets a genuine need.
>

HPKE supports both AES-GCM and ChaPoly and both COSE/JOSE HPKE drafts have
added both of them. Excluding it here would create a divergence from the
base HPKE specifications.


>
> Re: P-521, I think the main reason no one uses it is because it is
> incredibly slow.
>

Agreed.

Cheers,
-Tiru


>
> Neil
>
> On 19 Feb 2026, at 08:54, tirumal reddy <[email protected]> wrote:
>
> 
> A new section has been added to the draft to justify the combination of
> PQC-only and PQ/T hybrid KEMs with specific KDF and AEAD algorithms,
> https://www.ietf.org/archive/id/draft-reddy-cose-jose-pqc-hybrid-hpke-11.html#section-7.
> Please take a look and share any feedback, especially if there are concerns
> regarding the justification of particular KEM/KDF/AEAD pairings.
>
> Cheers,
> -Tiru
>
> On Thu, 12 Feb 2026 at 19:54, tirumal reddy <[email protected]> wrote:
>
>> Hi,
>>
>> We have updated the draft "Post-Quantum and Hybrid KEMs for HPKE with
>> JOSE and COSE"
>> https://datatracker.ietf.org/doc/draft-reddy-cose-jose-pqc-hybrid-hpke/
>> to version 10.  As many of you recall, this draft has been presented
>> multiple times in both COSE/JOSE WGs. While there was general interest, the
>> WG adoption of this draft was previously postponed to allow for the
>> completion COSE-HPKE and JOSE-HPKE specifications.
>>
>> With those base documents now mature, we have updated this draft to
>> ensure alignment with, JOSE/COSE HPKE and HPKE PQ specs.
>>
>> Further, comments and suggestions are welcome.
>>
>> we also request the Chairs to initiate a second WG adoption call for this
>> draft.
>>
>> Best Regards,
>> -Tiru
>>
>> -----Original Message-----
>> From: [email protected] <[email protected]>
>> Sent: Wednesday, February 11, 2026 6:04 PM
>> To: K Tirumaleswar Reddy (Nokia) <[email protected]>;
>> Hannes Tschofenig <[email protected]>; Hannes Tschofenig <
>> [email protected]>; K Tirumaleswar Reddy (Nokia) <
>> [email protected]>
>> Subject: New Version Notification for
>> draft-reddy-cose-jose-pqc-hybrid-hpke-10.txt
>>
>>
>> CAUTION: This is an external email. Please be very careful when clicking
>> links or opening attachments. See the URL nok.it/ext for additional
>> information.
>>
>>
>>
>> A new version of Internet-Draft
>> draft-reddy-cose-jose-pqc-hybrid-hpke-10.txt
>> has been successfully submitted by Tirumaleswar Reddy and posted to the
>> IETF repository.
>>
>> Name:     draft-reddy-cose-jose-pqc-hybrid-hpke
>> Revision: 10
>> Title:    Post-Quantum and Hybrid KEMs for HPKE with JOSE and COSE
>> Date:     2026-02-11
>> Group:    Individual Submission
>> Pages:    21
>> URL:
>> https://www.ietf.org/archive/id/draft-reddy-cose-jose-pqc-hybrid-hpke-10.txt
>> Status:
>> https://datatracker.ietf.org/doc/draft-reddy-cose-jose-pqc-hybrid-hpke/
>> HTML:
>> https://www.ietf.org/archive/id/draft-reddy-cose-jose-pqc-hybrid-hpke-10.html
>> HTMLized:
>> https://datatracker.ietf.org/doc/html/draft-reddy-cose-jose-pqc-hybrid-hpke
>> Diff:
>> https://author-tools.ietf.org/iddiff?url2=draft-reddy-cose-jose-pqc-hybrid-hpke-10
>>
>> Abstract:
>>
>>    This document specifies the use of Post-Quantum (PQ) and Post-
>>    Quantum/Traditional (PQ/T) Hybrid Key Encapsulation Mechanisms (KEMs)
>>    within the Hybrid Public Key Encryption (HPKE) for JOSE and COSE.  It
>>    defines algorithm identifiers and key formats to support pure post-
>>    quantum algorithms (ML-KEM) and their PQ/T hybrid combinations.
>>
>>
>>
>> The IETF Secretariat
>>
>>
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