Re: [TLS] Making post-handshake messages optional in TLS 1.3 (#676)

Ilari Liusvaara <ilariliusvaara@welho.com> Sat, 08 October 2016 16:53 UTC

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Date: Sat, 8 Oct 2016 19:53:00 +0300
From: Ilari Liusvaara <ilariliusvaara@welho.com>
To: Nick Sullivan <nicholas.sullivan@gmail.com>
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Subject: Re: [TLS] Making post-handshake messages optional in TLS 1.3 (#676)
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On Sat, Oct 08, 2016 at 04:32:32PM +0000, Nick Sullivan wrote:
> I'm not proposing any new post-handshake authentication mechanisms or
> anything relating to HTTP/2 renegotiation in this change. I'm simply making
> support for the existing post-handshake messages optional.
> 
> With this change, if the client does not opt in, unexpected
> CertificateRequests are fatal to the connection. Same with unexpected
> KeyUpdates and SessionTickets. This will hopefully reduce the complexity of
> TLS 1.3 implementations that don't need these features.

I really don't think making KeyUpdate optional is a good idea.

SessionTicket: Just don't send it / ignore it on reception.


What makes CertificateRequest really annoying is that one can't just
simply dismiss or NAK it. There are two messages involved, one
involving a MAC.

And furthermore, one must be quite careful in use of post-handshake
auth to not get subtle security issues.



-Ilari