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Re: [TLS] draft-ietf-tls-renegotiation-01.txt and DTLS

Eric Rescorla <ekr@networkresonance.com> Mon, 30 November 2009 18:29 UTC

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Date: Mon, 30 Nov 2009 10:29:56 -0800
From: Eric Rescorla <ekr@networkresonance.com>
To: Michael Tüxen <Michael.Tuexen@lurchi.franken.de>
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Subject: Re: [TLS] draft-ietf-tls-renegotiation-01.txt and DTLS
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At Mon, 30 Nov 2009 19:23:22 +0100,
Michael Tüxen wrote:
> 
> On Nov 30, 2009, at 7:06 PM, Marsh Ray wrote:
> 
> > Michael Tüxen wrote:
> >> 
> >> If I'm not wrong, then the attack which works against TLS does not
> >> work against DTLS, since DTLS has an epoch counter.
> >> 
> >> If a client tries to establish a DTLS connection and a MITM intercepts
> >> it, establishes itself a DTLS connection, the epoch is 1. There will be
> >> a final mismatch in the epoch and the packets will be discarded. When
> >> using the RI extension one could enforce the sending of the alert message.
> >> But the original attack is not possible, I think.
> >> 
> >> Is my analysis correct or am I overlooking something?
> > 
> > Can MitM do the same number of renegotitations as he does with the
> > server before splicing him?
> Good point, I missed that. So DTLS is also affected.
> 
> Could we then make it clear the that the RI extension applies to
> TLS and DTLS?

Yep. I'll add it to my TODO list.

-Ekr

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