If we assume AKP, and there is a desire to restrict a key to only
integrated encryption, then the algorithm identifiers would need to be
updated.

I can buy the security argument that it should be possible to restrict a
key to only integrated encryption... Especially because with key encryption
a weaker recipient could be attacked leading to disclosure.

Having a way to distinguish the supported  algorithms also fits with the
spirit of fully specified algorithms.

Regards,

OS

On Wed, Oct 22, 2025, 1:09 AM tirumal reddy <[email protected]> wrote:

> I am good to proceed with defining a new key type for PQC KEMs and to keep
> the "alg" parameter optional. Implementations that require strict algorithm
> binding can mandate the presence of "alg".  The "alg" field can be omitted
> when the same key structure is reused across different modes, such as
> direct encryption and key wrap similar to the way "alg" is not specified
> for the existing OKP key type.
>
> Cheers,
> -Tiru
>
> On Wed, 22 Oct 2025 at 03:04, Brian Campbell <bcampbell=
> [email protected]> wrote:
>
>> Apologies, the beginning of the text in the parenthetical of that last
>> sentence should have said "I'm *not* totally convinced myself"
>>
>> On Tue, Oct 21, 2025 at 1:34 PM Brian Campbell <
>> [email protected]> wrote:
>>
>>> Agree with much of Orie's perspective here.
>>>
>>> Please do not attempt to redefine AKP.
>>>
>>> If consensus is that AKP isn't right for keys for PQ KEMs (I'm
>>> totally convinced myself but I do definitely understand some of the
>>> rationale), then new key type(s) are the appropriate way forward.
>>>
>>> On Sat, Oct 11, 2025 at 7:32 AM Orie <[email protected]> wrote:
>>>
>>>> I left comments on https://github.com/tireddy2/PQC_JOSE_COSE/pull/19
>>>>
>>>> I will repeat them here for the list.
>>>>
>>>> Do not update the definition of AKP.
>>>>
>>>> Make a new key type if you want to have keys that have a different set
>>>> of security properties (such as being explicitly used with multiple
>>>> algorithms).
>>>>
>>>> If you want to go this route, I would lean into the idea that you can't
>>>> actually enforce any algorithm checking at the key side, and just say that
>>>> the attacker controlling the algorithm in the message is not a concern for
>>>> kems.
>>>> (I don't agree with this, but that's what the argument appears to be to
>>>> me, please correct me if I am wrong).
>>>>
>>>> In JOSE and COSE, the algorithm on security objects is controlled by
>>>> the attacker.
>>>> Without requiring the algorithm to be on the key, you will need to "try
>>>> it out" to see if it works.
>>>> As soon as you do that, you are doing work for the attacker... The
>>>> system may still fail closed, but you've already done more work than you
>>>> needed to.
>>>>
>>>> It's easy to make a new key type, if the WG thinks a key type that can
>>>> explicitly be used with many algorithms is a good thing, make one, that way
>>>> people will know what they are getting when they see that key type.
>>>>
>>>> Regards,
>>>>
>>>> OS
>>>>
>>>>
>>>>
>>>> On Sat, Oct 11, 2025 at 8:09 AM Neil Madden <[email protected]>
>>>> wrote:
>>>>
>>>>>
>>>>>
>>>>> > On 11 Oct 2025, at 13:24, Ilari Liusvaara <[email protected]>
>>>>> wrote:
>>>>> >
>>>>> > On Sat, Oct 11, 2025 at 10:29:59AM +0100, Neil Madden wrote:
>>>>> >>
>>>>> https://neilmadden.blog/2018/09/30/key-driven-cryptographic-agility/
>>>>> >
>>>>> > AKP is incompatible with key driven cryptographic agility.
>>>>> >
>>>>> > The idea of key driven cryptographic agility is to specify some
>>>>> > cryptographic service (e.g., signature, mac, KEM) at protocol level
>>>>> and
>>>>> > then have key specify how exactly that is implemented. And since this
>>>>> > is polymorphic by definition, KDCA is also incompatible with fully
>>>>> > specified algorithms.
>>>>>
>>>>> None of these things is true.
>>>>>
>>>>> — Neil
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