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Re: [TLS] Encrypted SNI

Ilari Liusvaara <ilariliusvaara@welho.com> Fri, 02 June 2017 14:21 UTC

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Date: Fri, 02 Jun 2017 17:21:36 +0300
From: Ilari Liusvaara <ilariliusvaara@welho.com>
To: Toerless Eckert <tte@cs.fau.de>
Cc: "<tls@ietf.org>" <tls@ietf.org>
Message-ID: <20170602142136.GA20535@LK-Perkele-V2.elisa-laajakaista.fi>
References: <CAHbuEH4Bwr13T-cBFvLmUmn6KRzuNf1su6VTeJguyssk6S2z3g@mail.gmail.com> <4d2f195a-c61b-4abb-9b33-bc36773775cd@cisco.com> <20170602084300.GB12522@faui40p.informatik.uni-erlangen.de> <CAL02cgS+eym_=TNupJo0f0qAFgZc14rXNfO=VdGzRX28jXVqkQ@mail.gmail.com> <20170602103151.GC12522@faui40p.informatik.uni-erlangen.de> <CAErg=HG8NFmuX7NUR3tLXbstzj2Spgc_dyh6b5DZqCFh73dt=Q@mail.gmail.com> <20170602132833.GE12522@faui40p.informatik.uni-erlangen.de>
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Subject: Re: [TLS] Encrypted SNI
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On Fri, Jun 02, 2017 at 03:28:33PM +0200, Toerless Eckert wrote:
> On Fri, Jun 02, 2017 at 08:03:40AM -0400, Ryan Sleevi wrote:
> > > If a web service hoster does not provide any useful demultiplexer then it
> > > can of course not
> > > expect not to get blacklisted across services. Is it not already common
> > > practice to assign
> > > separate certificates to separate "web customers" ?
> > 
> > No. It's typically the opposite.
> 
> Thanks.
> 
> Btw: does TLS 1.3 mandate server side cert encryption or is this something server
> apps can decide ? 

It is required.

Of server messages, TLS 1.3 only leaves ServerHello unencrypted. SH
contains low-level connection parameters:

- TLS version used
- Server random value
- Record protection / PRF algorithm used
- DH key share (if DH is used).
- PSK identity selected (if PSK is used).


The certificate is sent in certificate message, which is always
protected (encrypted).


-Ilari

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