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Re: [TLS] Encrypting record headers: practical for TLS 1.3 after all?

Bryan A Ford <brynosaurus@gmail.com> Mon, 30 November 2015 10:02 UTC

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To: "Short, Todd" <tshort@akamai.com>, Peter Gutmann <pgut001@cs.auckland.ac.nz>
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From: Bryan A Ford <brynosaurus@gmail.com>
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Date: Mon, 30 Nov 2015 11:02:31 +0100
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Subject: Re: [TLS] Encrypting record headers: practical for TLS 1.3 after all?
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On 11/30/15 2:54 AM, Short, Todd wrote:
> This brings up an interesting point; having a record length that corresponds to the TCP segment size can help hardware implementations such that they don't need to deal with scatter/gather; i.e. one TCP segment corresponds to a single TLS record. This goes along with 8 (or 4) byte record lengths for hardware implementations. 

This is wildly unsafe to assume or depend on for all sorts of reasons;
TCP streams regularly get merged or re-segmented in the network in a
variety of unpredictable ways (e.g., by middleboxes).  See my earlier
E-mail discussing that issue extensively.

B

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