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Re: [TLS] TLS client puzzles

Hannes Tschofenig <hannes.tschofenig@gmx.net> Wed, 06 July 2016 20:23 UTC

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To: Kyle Rose <krose@krose.org>
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From: Hannes Tschofenig <hannes.tschofenig@gmx.net>
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Date: Wed, 06 Jul 2016 22:23:23 +0200
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Cc: "<tls@ietf.org>" <tls@ietf.org>, Dmitry Khovratovich <khovratovich@gmail.com>
Subject: Re: [TLS] TLS client puzzles
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Kyle,

the question for me is whether it will be an effective mechanism when
many devices just do not support it (for a number of reasons)? For IoT
devices the reason is simple: they don't have MBs of memory.

Even the regular puzzle technique has the problem that you have to
adjust the puzzle difficulty and what is a piece of cake for a desktop
computer kills the battery of an IoT device.

(And note that I am not saying that IoT devices aren't used for DDoS
attacks.)

On 07/06/2016 10:16 PM, Kyle Rose wrote:
> On Wed, Jul 6, 2016 at 4:08 PM, Hannes Tschofenig
> <hannes.tschofenig@gmx.net <mailto:hannes.tschofenig@gmx.net>> wrote:
> 
>     I agree with Brian here on this issue. This is clearly impractical for
>     IoT devices. For many of those devices we are talking about 32 KB (in
>     total). 
> 
>  
> I continue to feel like this is a valid objection to the wrong
> proposition. I don't think the question is, "Should TLS client puzzles
> be issued by all TLS servers under load?" but rather, "Would client
> puzzles be a useful addition to the DDoS toolbox, and appropriate in
> some cases?"
> 
> Kyle
>

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