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Re: [TLS] Remove 0-RTT client auth

Eric Rescorla <ekr@rtfm.com> Sun, 21 February 2016 19:44 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Sun, 21 Feb 2016 11:43:21 -0800
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To: Cedric Fournet <fournet@microsoft.com>
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Subject: Re: [TLS] Remove 0-RTT client auth
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Correct.

-Ekr


On Sun, Feb 21, 2016 at 11:41 AM, Cedric Fournet <fournet@microsoft.com>
wrote:

> Agreed. For what it is worth, 0-RTT with PSK would still provide implicit
> client authentication.
>
>
>
>
>
> *From:* TLS [mailto:tls-bounces@ietf.org] *On Behalf Of *Eric Rescorla
> *Sent:* 21 February 2016 19:37
> *To:* Martin Thomson <martin.thomson@gmail.com>
> *Cc:* tls@ietf.org
> *Subject:* Re: [TLS] Remove 0-RTT client auth
>
>
>
> +1
>
>
>
> On Sun, Feb 21, 2016 at 11:31 AM, Martin Thomson <martin.thomson@gmail.com>
> wrote:
>
> I'm sitting here in TRON listening to Karthik describe all the various
> ways in which client authentication in 0-RTT is bad.  I'm particularly
> sympathetic to the perpetual impersonation attack that arises when the
> client's ephemeral key is compromised.
>
> We originally thought that we might want to do this for
> WebRTC/real-time.  As it so happens, we have an alternative design
> that doesn't need this, so...
>
> I propose that we remove client authentication from 0-RTT.
>
> This should simplify the protocol considerably.
>
> https://github.com/tlswg/tls13-spec/issues/420
>
> [1] Compromising the server's long term key has the same impact, but
> that's interesting for other, worse reasons.
>
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