Re: [TLS] Rethink TLS 1.3

Ralph Holz <ralph.ietf@gmail.com> Sun, 23 November 2014 13:27 UTC

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Date: Sun, 23 Nov 2014 14:27:25 +0100
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From: Ralph Holz <ralph.ietf@gmail.com>
To: Watson Ladd <watsonbladd@gmail.com>
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Subject: Re: [TLS] Rethink TLS 1.3
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I'd disagree with the notion of "it is clear what TLS supports" - there is
no threat model describing the strength of an attacker (and there never has
been). It's not even clear what TLS means by "authentication".

As a possible step forward, we could say TLS supports authentication as
Lowe's injective agreement - a fairly strong definition yet one matching
intuitive expectation.

On 22 November 2014 at 23:15, Watson Ladd <watsonbladd@gmail.com>; wrote:

> On Sat, Nov 22, 2014 at 3:31 AM, Henrick Hellström <henrick@streamsec.se>;
> wrote:
> > On 2014-11-22 01:57, Watson Ladd wrote:
> >>
> >> Was the TLS 1.3 draft written by a cryptographer? No.
> >> Has it been reviewed by cryptographers? Unclear.
> >> Are the mechanisms secure? Unknown.
> >> Is it easy to analyze TLS 1.2? No.
> >> Was TLS 1.2 secure? No.
> >> Has TLS 1.3 fixed flaws in TLS 1.2? Some: session_hash remains
> >> unincluded, but the record layer is finally fixed.
> >
> >
> > I think such discussions would benefit from the basic premise that
> "secure"
> > is a relative notion. It is completely pointless to ask if a protocol is
> > secure or not secure, unless you first present an exhaustive list of
> > security claims. That is, you can't ask if TLS 1.3 is secure or not,
> without
> > first describing what security is to be expected from different
> scenarios.
>
> It's clear what the security claims of TLS are be: a TLS connection
> between two parties ensures that data sent between them isn't
> intercepted or manipulated, and that they are who they claim to be.
> This is a fairly standard notion, clearly present in research by the
> late 80's, and intuitively sensible.
>
> Of course, past versions of TLS haven't provided it.
>
> >
> > In a sense, *every* protocol has the potential of becoming broken,
> unless it
> > is unambiguously defined what is proper and improper usage of the
> protocol.
> >
> > _______________________________________________
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> > TLS@ietf.org
> > https://www.ietf.org/mailman/listinfo/tls
>
>
>
> --
> "Those who would give up Essential Liberty to purchase a little
> Temporary Safety deserve neither  Liberty nor Safety."
> -- Benjamin Franklin
>
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