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Re: [TLS] Remove deprecated fields in TLS 1.3

Benjamin Kaduk <bkaduk@akamai.com> Mon, 03 April 2017 04:29 UTC

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To: Arnaud Venturi <arnaud.venturi@rez-gif.supelec.fr>, tls@ietf.org
References: <1e493a03-6843-9afa-fbcb-e8659f0f4184@rez-gif.supelec.fr>
From: Benjamin Kaduk <bkaduk@akamai.com>
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Date: Sun, 02 Apr 2017 23:29:16 -0500
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Subject: Re: [TLS] Remove deprecated fields in TLS 1.3
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On 04/02/2017 03:33 AM, Arnaud Venturi wrote:
> I could not think of any security or interoperability issue with this
> proposal, the only drawback I can see being the slight complexity added
> in ClientHello parsing.

The ClientHello message needs to be interpreted in the same way by TLS
servers running all versions of TLS.  A TLS 1.0 server would not know to
use the changed interpretation of the fields and would fail to negotiate
a connection.  Basically, no change in the format is possible while
preserving the backwards and forwards compatibility of version negotiation.

-Ben

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