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Re: [TLS] RFC 6066 - Max fragment length negotiation

Martin Thomson <martin.thomson@gmail.com> Wed, 22 March 2017 02:04 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Wed, 22 Mar 2017 13:03:58 +1100
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To: Eric Rescorla <ekr@rtfm.com>
Cc: Peter Gutmann <pgut001@cs.auckland.ac.nz>, "tls@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] RFC 6066 - Max fragment length negotiation
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On 22 March 2017 at 12:01, Eric Rescorla <ekr@rtfm.com> wrote:
> The maximum amount of wastage in this case is E_max - E_min where E_min is
> the minimum amount of expansion of any cipher suite they support.

Right, I was concerned about the case where this difference is
(potentially) large.  That's all.

The main problem I see with a design that shifts complexity to the
sender is the economic one.  I want to provide as much incentive to
implement the sender side of this as possible, which means keeping it
simple.  If the cost of that is a little more complexity on receivers,
but only when using block ciphers, I think that I can live with that.
Given that the complexity is likely more in logic than it is code,
then I'm even more happy with what I've proposed.

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