Re: [TLS] DNS-based Encrypted SNI

Eric Rescorla <> Wed, 04 July 2018 18:20 UTC

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From: Eric Rescorla <>
Date: Wed, 04 Jul 2018 11:20:05 -0700
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To: Kathleen Moriarty <>
Cc: Stephen Farrell <>, "<>" <>
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Subject: Re: [TLS] DNS-based Encrypted SNI
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Hi Kathleen,

On Wed, Jul 4, 2018 at 11:10 AM, Kathleen Moriarty <> wrote:

> I’m also fine with the work going forward, however it was only in March
> that EKR assured people concerned that they don’t need to worry about SNI
> being encrypted repeating similar statements previously made to the same
> effect.  Meantime, he was working on such a solution.

This is not really correct. As of March, I had basically given up on how to
do ESNI in TLS the near future and wasn't really working on it [0] and then
in May, prompted by suggestions by Matthew Prince and Nick Sullivan, I
realized that the proposal in this document could work.

Moreover, I think I've been pretty clear that I wanted to do ESNI and it
was just that we didn't know how. For instance, here's what I said in

   My evaluation of the current state of SNI encryption is that given the
   current technical state, it will not see particularly wide deployment,
   the primary scenario being "at-risk" sites who are subject to censorship
   either hide behind or co-tenant with sites which are not subject to
   censorship. That probably isn't going to be incredibly common right now.
   course, this is regrettable from the perspective of people designing
   protocols, but I think that's the situation.

As I said the other day, predictions are hard, especially about the future,
and this turns out not to have been totally right (though I also don't
think it's really accurate to characterize it as my saying that people
don't need to worry). I'm sorry if people people are surprised now. That
wasn't my intent, but as I said above, I was surprised too!


[0] Just to be completely clear, there was and is ongoing work on
protecting SNI via HTTP connection coalescence (see Mike Bishop's
presentation in London), but that's a different flavor of approach, and
it's not like it's any secret it's happening.

> Kathleen
> >
> > Cheers,
> > S.
> >
> >
> >>
> >> -Ekr
> >>
> >>
> >>
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