Re: [TLS] FYI: new TLS HandshakeType allocation, from draft-ietf-perc-srtp-ekt-diet

Watson Ladd <watson@cloudflare.com> Fri, 30 August 2019 22:57 UTC

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From: Watson Ladd <watson@cloudflare.com>
Date: Fri, 30 Aug 2019 15:57:23 -0700
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To: Benjamin Kaduk <kaduk@mit.edu>
Cc: tls@ietf.org
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Subject: Re: [TLS] FYI: new TLS HandshakeType allocation, from draft-ietf-perc-srtp-ekt-diet
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On Fri, Aug 30, 2019 at 3:24 PM Benjamin Kaduk <kaduk@mit.edu>; wrote:
>
> Hi all,
>
> New values for core types like TLS HandshakeType and ContentType don't
> happen very often, so I thought people might be interested to know that
> draft-ietf-perc-srtp-ekt-diet (currently in IESG evaluation) is allocating
> a HandshakeType, to carry key information used to encrypt SRTP media key
> material.
> Obviously "it's never too late to change until the RFC is published", but I
> think there would need to be some pretty serious issues in order to change
> it at this point, so this is expected to just be an "FYI".

Design issues: Am I reading the doc right, that this handshake message
goes after the finished? And then contains a key that is used to
decrypt another key that is then used to decrypt (some) traffic, but
doesn't change the DTLS keys? Why is this a handshake message and not
some protocol framing in the protocol carried over DTLS? It just seems
funny to make it be a handshake type and not something else. It's
entirely possible this makes more sense if you know about DTLS-SRTP
which I do not very much.

>
> -Ben
>
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