Re: [quicwg/base-drafts] Remove amplification throttle if the server receives Initial that echoes its high entropy SCID. (#3834)

[ekr <[e-mail]>]

On Tue, Jul 7, 2020 at 6:26 PM Marten Seemann <[e-mail]>
wrote:

> This would be conditional on the server choosing a connection ID that has
> enough entropy (we seem to have decided that 64 bits is the benchmark).
> @huitema <https://github.com/huitema> has made the same comment on
> occasion.
>
> How would a client know how what algorithm the server used to generate the
> connection ID?
>
The client doesn't need to know, because it's the server's amplification
limit that is at hand. And right now, the handshake would complete if the
client doesn't do anything, it's just not optimal.

As this seems to be a design issue anyway, here's another proposal: The
> server could send a token in the Initial packet, and the client would then
> use this token on subsequent Initial packets (replacing the token it might
> have used on the packet containing the ClientHello). This way, we'd be
> using a field that's intended to carry a high-entropy value, and not rely
> on a field that the server might not even have control over.
>
I agree that this would work, but it seems like a significantly more
invasive change, especially given the somewhat edge-casey nature of the
issue.


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