Re: [TLS] cross-domain cache sharing and 0rtt
Eric Rescorla <ekr@rtfm.com> Fri, 30 December 2016 17:57 UTC
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From: Eric Rescorla <ekr@rtfm.com>
Date: Fri, 30 Dec 2016 09:56:18 -0800
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To: Ilari Liusvaara <ilariliusvaara@welho.com>
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Cc: Adam Langley <agl@imperialviolet.org>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] cross-domain cache sharing and 0rtt
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On Fri, Dec 30, 2016 at 9:21 AM, Ilari Liusvaara <ilariliusvaara@welho.com> wrote: > On Fri, Dec 30, 2016 at 08:14:57AM -0800, Eric Rescorla wrote: > > On Fri, Dec 30, 2016 at 6:43 AM, Stephen Farrell < > stephen.farrell@cs.tcd.ie> > > wrote: > > > > > > What I'm wondering is if we're maybe missing a server-side check > > > on that, with the possible attempted attack of a 0rtt replay in > > > mind. E.g. a MUST check for the server that SNI is the same as for > > > initial h/s before processing early data, (as is done for ALPN now) > > > and/or some guidance about what might not be an obvious relationship > > > between any 0rtt replay detection mechanisms and session ticket > > > equivalents > > > > > > I believe that the text I quote below already requires that check. The > > reason > > it's there and not in the 0-RTT text is that it is a requirement on > > resumption > > which itself is a requirement for 0-RTT. The ALPN check is an explicit > 0-RTT > > requirement but not a resumption requirement. > > > > I.e., > > Can resume only if SNI is equal > > Can accept 0-RTT only if (resumed && ALPN is equal) > > Actually, AFAICT all types of PSKs can be used for 0-RTT if all the > needed data is provisioned. But AFAICT only dynamically provisioned > PSKs have SNI requirements. > > So statically provisioned ("external") PSKs AFAICT can do 0-RTT across > SNI values. > Yes, I think that would be permitted by this text, though that's just a result of bad writing, which would be resolved by saying that you must only accept a PSK (rather than resume) if the SNIs are equal. -Ekr > > > > -Ilari >
- Re: [TLS] Requiring that (EC)DHE public values be… Martin Rex
- [TLS] Requiring that (EC)DHE public values be fre… Adam Langley
- Re: [TLS] Requiring that (EC)DHE public values be… Stephen Farrell
- Re: [TLS] Requiring that (EC)DHE public values be… Eric Rescorla
- [TLS] cross-domain cache sharing and 0rtt (was: R… Stephen Farrell
- Re: [TLS] cross-domain cache sharing and 0rtt (wa… Eric Rescorla
- Re: [TLS] Requiring that (EC)DHE public values be… Adam Langley
- Re: [TLS] cross-domain cache sharing and 0rtt (wa… Adam Langley
- Re: [TLS] Requiring that (EC)DHE public values be… Brian Smith
- Re: [TLS] cross-domain cache sharing and 0rtt (wa… Ilari Liusvaara
- Re: [TLS] cross-domain cache sharing and 0rtt (wa… Richard Barnes
- Re: [TLS] cross-domain cache sharing and 0rtt Stephen Farrell
- Re: [TLS] cross-domain cache sharing and 0rtt Eric Rescorla
- Re: [TLS] cross-domain cache sharing and 0rtt Stephen Farrell
- Re: [TLS] cross-domain cache sharing and 0rtt Ilari Liusvaara
- Re: [TLS] cross-domain cache sharing and 0rtt Eric Rescorla
- Re: [TLS] cross-domain cache sharing and 0rtt Bill Frantz
- Re: [TLS] cross-domain cache sharing and 0rtt Stephen Farrell
- Re: [TLS] Requiring that (EC)DHE public values be… Scott Schmit
- Re: [TLS] Requiring that (EC)DHE public values be… Adam Langley
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Hugo Krawczyk
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Dan Brown
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Ilari Liusvaara
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Peter Gutmann
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Hugo Krawczyk
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Yoav Nir
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Eric Rescorla
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Ilari Liusvaara
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Eric Rescorla
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Yoav Nir
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Colm MacCárthaigh
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Adam Langley
- Re: [TLS] cross-domain cache sharing and 0rtt Benjamin Kaduk
- Re: [TLS] cross-domain cache sharing and 0rtt Ilari Liusvaara
- Re: [TLS] cross-domain cache sharing and 0rtt Martin Thomson
- Re: [TLS] cross-domain cache sharing and 0rtt Benjamin Kaduk
- Re: [TLS] cross-domain cache sharing and 0rtt Ilari Liusvaara
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Adam Langley
- Re: [TLS] [SUSPECTED URL!]Re: Requiring that (EC)… Kurt Roeckx