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

Martin Thomson <martin.thomson@gmail.com> Wed, 23 November 2016 00:36 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Wed, 23 Nov 2016 11:36:42 +1100
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To: Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [TLS] Draft 18 review : Message splitting and interleaving
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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.)

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

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