Regarding #1, I believe kem_id could be optional but it's acceptable for
me. I do not disagree.
Of course I agree with #2 but let me add one thing.
I was opposed to an overly polymorphic approach ( bstr / [*any] / {* any =>
any } ) but for example, the following definition can be acceptable for me:
`encapsulation _key / encapsulation_key_for_auth_mode /
encapsulation_key_for_psk_mode ...`
However, this topic can be discussed when other HPKE modes are needed.
In conclusion, I agree with both of them.
--
Daisuke
2023年1月12日(木) 2:56 Mike Prorock <[email protected]>:
> +1 as well
>
> Mike Prorock
> mesur.io
>
> On Wed, Jan 11, 2023, 10:54 Orie Steele <[email protected]> wrote:
>
>>
>> On Wed, Jan 11, 2023 at 10:44 AM Laurence Lundblade <
>> [email protected]> wrote:
>>
>>> I’m in favor of both of these.
>>>
>>> In addition to previous reasons in favor of #2, the use of COSE’s
>>> mechanism for distinguishing one sort of parameter (parameter labels) seems
>>> better than making up a new mechanism (polymorphism of a parameter).
>>>
>>
>> I agree.
>>
>>
>>> COSE implementations already have to decode header parameter labels and
>>> switch on them. Many will have code handy for this.
>>>
>>
>>> LL
>>>
>>>
>>> On Jan 11, 2023, at 4:51 AM, Hannes Tschofenig <
>>> [email protected]> wrote:
>>>
>>> Hi all,
>>>
>>> To move forward with the COSE-HPKE draft two open issues need to be
>>> addressed. I posted a mail in December, see
>>> https://mailarchive.ietf.org/arch/msg/cose/Cv-UumRRmmXWzrDHAhOAk0iV6fI/
>>>
>>> The two open issues (IMHO) are:
>>>
>>>
>>> 1. Should we make the kem_id in the encapsulated_key structure
>>> mandatory, as Laurence suggested.
>>> 2. Should we avoiding the polymorphic approach for the
>>> encapsulated_key registration, as Daisuke suggested.
>>>
>>> To make it easier to understand these two issues, let me point you the
>>> current version of the PR:
>>>
>>> https://github.com/cose-wg/HPKE/blob/9914fa6f84b28046ee29762551798760dbaa3b7f/draft-ietf-cose-hpke.md
>>>
>>> Regarding issue#1, we are talking about changing the encapsulated_key
>>> structure
>>>
>>> from
>>>
>>>
>>>
>>> encapsulated_key = [
>>>
>>> kdf_id : uint, ; kdf id
>>>
>>> aead_id : uint, ; aead id
>>>
>>> enc : bstr, ; enc
>>>
>>> ? kem_id : uint, ; kem id
>>>
>>> ]
>>>
>>>
>>> to:
>>>
>>>
>>> encapsulated_key = [
>>>
>>> kdf_id : uint, ; kdf id
>>>
>>> aead_id : uint, ; aead id
>>>
>>> kem_id : uint, ; kem id
>>>
>>> enc : bstr, ; enc
>>>
>>> ]
>>>
>>>
>>>
>>> Regarding issue#2, the change relates to how the encapsulated_key
>>> structure is registered in the COSE IANA registry (under COSE header
>>> parameters).
>>>
>>> Change from:
>>>
>>> - Name: encapsulated_key
>>> - Label: TBD2 (Assumed: -4)
>>> - Value type: bstr / [*any] / {* any => any }
>>> - Value Registry: N/A
>>> - Description: Encapsulated key for KEM-like algorithms
>>>
>>> To:
>>>
>>> - Name: encapsulated_key
>>> - Label: TBD2 (Assumed: -4)
>>> - Value type: Array
>>> - Value Registry: N/A
>>> - Description: Encapsulated key for KEM-like algorithms
>>>
>>>
>>> In a future, if the HPKE gets extended to algorithms that are not
>>> compatible with the encapsulated_key structure then a new one has to be
>>> defined due to the lack of extensibility of the array and its fixed set of
>>> fields.
>>>
>>> Your feedback will be valuable and allows me to resubmit a new draft
>>> version.
>>>
>>> Ciao
>>> Hannes
>>>
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>>
>>
>> --
>> *ORIE STEELE*
>> Chief Technical Officer
>> www.transmute.industries
>>
>> <https://www.transmute.industries>
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>>
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