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Re: [TLS] Final (hopefully) issues with DTLS 1.2

Nikos Mavrogiannopoulos <nmav@gnutls.org> Fri, 03 June 2011 21:16 UTC

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Date: Fri, 03 Jun 2011 23:16:54 +0200
From: Nikos Mavrogiannopoulos <nmav@gnutls.org>
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To: Eric Rescorla <ekr@rtfm.com>
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Cc: tls@ietf.org
Subject: Re: [TLS] Final (hopefully) issues with DTLS 1.2
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On 06/03/2011 10:09 PM, Eric Rescorla wrote:

>> My implementation of this HelloVerifyRequest was made without using or
>> allocating server state. That means it doesn't even know which (DTLS)
>> protocols are enabled or not. It could even be implemented in a
>> totally different subsystem (a firewall) in front of the server. Thus it
>> might not know information the server knows. For me this packet
>> should be as simple as possible. Using a fixed DTLS version would
>> satisfy this goal. I see no benefit from doing the DTLS version number
>> negotiation at this "stateless" point.
> I don't see a problem with the server echoing the client's version number
> here. Does anyone disagree with making an explicit exemption in the spec
> for that?

By reflecting the version back you lose the ability to use a different
format later on (under another version number). It might be better to
just fix it to a protocol number, e.g. DTLS 1.0, and if the format
changes then some other number is used.

regards,
Nikos

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