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Re: [TLS] Draft 18 review : Message splitting and interleaving

Eric Rescorla <ekr@rtfm.com> Wed, 23 November 2016 00:45 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Tue, 22 Nov 2016 16:45:09 -0800
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] Draft 18 review : Message splitting and interleaving
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On Tue, Nov 22, 2016 at 4:36 PM, Martin Thomson <martin.thomson@gmail.com>
wrote:

> On 23 November 2016 at 10:24, Eric Rescorla <ekr@rtfm.com> wrote:
> >>   [EncryptedExtensions Certifi]
> >>   [cateRequest Certificate Cer]
> >>   [tificateVerify Finished]
> >
> >
> > Yeah, that's how this works in NSS.
>
> To be clear, NSS buffers an entire flight of messages and then sends
> them.  It might fragment things between TCP segments as a result, but
> usually fits everything in a single record (with some exceptions,
> thanks to CertificateRequest being bloated, foor example).  (In DTLS,
> it's more complicated because we have MTU detection, but the same
> basic principle applies.)
>

Yes, this is what I meant to say. Basically, it tries to cram as much as it
can into
one record and the answer to "as much as it can" is "it depends"

-Ekr


Like others, I would find stricter rules around record splits very
> hard to enforce, and for not much gain.
>

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