Re: [TLS] TLS client puzzles
Kyle Rose <krose@krose.org> Thu, 07 July 2016 21:46 UTC
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From: Kyle Rose <krose@krose.org>
Date: Thu, 07 Jul 2016 17:36:58 -0400
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To: Bill Cox <waywardgeek@google.com>
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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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> I agree, and I think it is clear that client puzzles can be a useful > addition to the DDoS defense toolbox. However, most of this can be handled > at the higher levels above TLS, or possibly as a custom extension that does > not complicate TLS. > A custom extension is a promising approach: this is what Erik Nygren proposed in nygren-tls-client-puzzles-00 following discussions with some IETF folks and Akamai colleagues. That draft has expired and doesn't reference any of the recent work on memory-hard puzzles, but it might be a good starting point. Except at the pre-TLS stage for applications that use STARTTLS-style mechanisms, I'm not sure how this could work at levels above TLS: the primary attack targeted by client puzzles would be a client doing almost no work in order to force the server to do expensive crypto, which means it must be engaged prior to the handshake. Kyle
- Re: [TLS] TLS client puzzles Erik Nygren
- Re: [TLS] TLS client puzzles Kyle Rose
- Re: [TLS] TLS client puzzles Bill Cox
- Re: [TLS] TLS client puzzles Peter Gutmann
- Re: [TLS] TLS client puzzles Dave Garrett
- Re: [TLS] TLS client puzzles Kyle Rose
- Re: [TLS] TLS client puzzles Hannes Tschofenig
- Re: [TLS] TLS client puzzles Hannes Tschofenig
- Re: [TLS] TLS client puzzles Tony Arcieri
- Re: [TLS] TLS client puzzles Kyle Rose
- Re: [TLS] TLS client puzzles Salz, Rich
- Re: [TLS] TLS client puzzles Hannes Tschofenig
- Re: [TLS] TLS client puzzles David Adrian
- Re: [TLS] TLS client puzzles Yoav Nir
- Re: [TLS] TLS client puzzles Valery Smyslov
- Re: [TLS] TLS client puzzles Christian Huitema
- Re: [TLS] TLS client puzzles Geoffrey Keating
- Re: [TLS] TLS client puzzles Kyle Rose
- Re: [TLS] TLS client puzzles Kyle Rose
- Re: [TLS] TLS client puzzles Christian Huitema
- Re: [TLS] TLS client puzzles Kyle Rose
- Re: [TLS] TLS client puzzles Brian Smith
- [TLS] TLS client puzzles Dmitry Khovratovich
- Re: [TLS] TLS client puzzles Bill Cox