Unfortunately, we don’t support certificate compression yet. I’d also be interested in seeing the data with that enabled. I need to go see if/how I can use that with OpenSSL.
- Nick Sent from Outlook<http://aka.ms/weboutlook> From: Ian Swett <[email protected]> Sent: Wednesday, July 31, 2024 12:07 PM To: Christian Huitema <[email protected]> Cc: Paul Vixie <[email protected]>; IETF QUIC WG <[email protected]>; Nick Banks <[email protected]> Subject: Re: Proposal: Increase QUIC Amplification Limit to 5x We found that once we deployed certificate compression, we could typically keep the cert under 3 packets, but without it, we typically went over. I believe one reason the QUIC WG chose 3 is because we had data to show that most certificates were small enough once compressed to enable a 1 RTT handshake. I'd be curious what your results are with and without certificate compression in your client? On Wed, Jul 31, 2024 at 11:15 AM Christian Huitema <[email protected]<mailto:[email protected]>> wrote: On 7/30/2024 5:52 PM, Paul Vixie wrote: > Do we know a reason why the system's behavior won't move beyond the new > limit the same way it moved beyond the old one? If it's some bizarre > kind of leaky bucket let's have the showdown now rather than later when > everything is larger and ossification has begun. The concern is that the wily hackers will send a single UDP "initial" packet to a server, and the the server will reply with a complete flight of packets including key exchanges, parameters and certificates. Send 1.2KB to the server, see the server send back 5, 6 or maybe 10 packets to the source IP of the UDP packet. With that the DDOS attack has been "amplified" 5, 6 or maybe 10 times. The amplification limit is there to limit the usefulness of QUIC servers for these DDOS attackers. The value 3 was chosen because with "reasonable" configurations the server's first flight fits in 2 or 3 packets, and that there are many UDP services that provide more than 3x amplification (see https://www.cisa.gov/news-events/alerts/2014/01/17/udp-based-amplification-attacks). But if we loosen the QUIC amplification limit while other services are tightening, that situation will change. -- Christian Huitema
