[AVTCORE] Re: STUN SHA-256 usage in WebRTC (ICE and TURN)

[Philipp Hancke <[e-mail]>]

Am Mi., 29. Apr. 2026 um 18:32 Uhr schrieb Roman Shpount <[e-mail]
>:

> On Wed, Apr 29, 2026 at 12:20 PM Roman Shpount <[e-mail]> wrote:
>
>> It looks like the details of the MESSAGE-INTEGRITY-SHA256 implementation
>> were fully considered. What is described in RFC 8489 is counterproductive.
>> If MESSAGE-INTEGRITY-SHA256 is comprehension-required, including
>> MESSAGE-INTEGRITY also makes STUN messages less secure. It should have been
>> in the comprehension-optional range.
>>
>> You should also consider the increase in STUN message size. Adding
>> optional MESSAGE-INTEGRITY-SHA256 will result in an extra 32 bytes in each
>> STUN request.
>>
>
> I meant to say the details of the MESSAGE-INTEGRITY-SHA256 implementation
> were NOT fully considered.
>

Heh! I assume the RFC is not fixable as an error but requires an update?

The downgrade attack argument is good (applies to most hash agility plans I
have seen though?) but if we need an ice-option or url parameter anyway it
goes away.
This reduces the concern about increasing overhead on initial messages
requests would have to include both variants (4+20 plus 4 + 32) so we are
only increasing packet size by 12 bytes?

Thanks Roman for helping me think!

>