Re: [TLS] Negotiate only symmetric cipher via cipher suites (was: Ala Carte Cipher suites - was: DSA should die)
Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Mon, 13 April 2015 18:55 UTC
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Date: Mon, 13 Apr 2015 21:55:05 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
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References: <CAK9dnSyKf7AY11h1i1h+SudRc-NmTZE5wC682YKhNsxnfV5ShQ@mail.gmail.com> <201504131200.00384.davemgarrett@gmail.com> <874mokug5y.fsf@alice.fifthhorseman.net> <201504131325.20590.davemgarrett@gmail.com> <871tjoue8v.fsf@alice.fifthhorseman.net> <D1517606.23FD5%uri@ll.mit.edu> <87vbgzubj6.fsf@alice.fifthhorseman.net>
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Subject: Re: [TLS] Negotiate only symmetric cipher via cipher suites (was: Ala Carte Cipher suites - was: DSA should die)
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On Mon, Apr 13, 2015 at 02:29:49PM -0400, Daniel Kahn Gillmor wrote: > On Mon 2015-04-13 13:35:42 -0400, Blumenthal, Uri - 0553 - MITLL wrote: > > On 4/13/15, 13:31 , "Daniel Kahn Gillmor" <dkg@fifthhorseman.net> wrote: > > > >>On Mon 2015-04-13 13:25:20 -0400, Dave Garrett wrote: > >>>> So if we have to have non-(EC)DHE PSK, what would it mean if a TLS peer > >>>> were to try to negotiate: > >>>> > >>>> key agreement: PSK > >>>> authentication: RSA-PSS > >>>> > >>>> Do we just say "don't do that"? > >>> > >>> SGTM > >> > >>……... > >>Once the full cartesian explosion is available by multidimensional > >>enumeration, we have to mark out which corners of the space are actually > >>bad ideas, and we have to make sure our implementations don't stumble > >>into those corners by accident. > >> > >>This isn't impossible to do, but it seems ripe for subtle implementation > >>bugs. > > > > Cryptographically sound algorithms and protocols should be immune to this > > concern. And we should accept only cryptographically sound algorithms & > > protocols. :-) > > What do you think an implementation should do when a peer tries to > negotiate the combination above? Require an RSA-PSS signature from the > server over some material derived in part from the PSK key agreement > mechanism? To me it seems like that combo is quite insecure, unless one handles it as a special case (in which case it is just equivalent to PSK in security, just wastes time with a certificate). As list, the key exchange methods TLS v1.2 actually supports (after merging some non-significant distinctions) are: - RSA [going away] - RSA_EXPORT [you have deimplemented this already, right?] - DH_CERT [going away] - DHE_CERT [supported] - DHE_ANON [???] - KRB5 [going away] - PSK [???] - DHE_PSK [???] - RSA_PSK [going away] - SRP [???] - SRP_CERT [???] -Ilari
- Re: [TLS] DSA should die Yoav Nir
- Re: [TLS] DSA should die Dave Garrett
- [TLS] DSA should die Hanno Böck
- Re: [TLS] DSA should die Aaron Zauner
- Re: [TLS] DSA should die David Benjamin
- Re: [TLS] DSA should die Stephen Checkoway
- Re: [TLS] DSA should die Tony Arcieri
- Re: [TLS] DSA should die Bill Frantz
- Re: [TLS] DSA should die Tom Ritter
- Re: [TLS] DSA should die Viktor Dukhovni
- Re: [TLS] DSA should die Stephen Farrell
- Re: [TLS] DSA should die Nico Williams
- Re: [TLS] DSA should die Stephen Farrell
- Re: [TLS] DSA should die Viktor Dukhovni
- Re: [TLS] DSA should die Dave Garrett
- Re: [TLS] DSA should die Martin Thomson
- Re: [TLS] DSA should die Nico Williams
- Re: [TLS] DSA should die Martin Rex
- Re: [TLS] DSA should die Watson Ladd
- Re: [TLS] DSA should die Nico Williams
- Re: [TLS] DSA should die CodesInChaos
- Re: [TLS] DSA should die Martin Thomson
- Re: [TLS] DSA should die Dave Garrett
- Re: [TLS] DSA should die Nico Williams
- Re: [TLS] DSA should die Ilari Liusvaara
- Re: [TLS] DSA should die Joseph Salowey
- Re: [TLS] DSA should die Kurt Roeckx
- Re: [TLS] DSA should die Michael StJohns
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Michael StJohns
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Brian Smith
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Tony Arcieri
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Martin Thomson
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Dave Garrett
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Aaron Zauner
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Dave Garrett
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Viktor Dukhovni
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Salz, Rich
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Tony Arcieri
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Yoav Nir
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Brian Smith
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Tony Arcieri
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Ilari Liusvaara
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Brian Sniffen
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Viktor Dukhovni
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Viktor Dukhovni
- Re: [TLS] Negotiate only symmetric cipher via cip… Dave Garrett
- Re: [TLS] Negotiate only symmetric cipher via cip… Daniel Kahn Gillmor
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Aaron Zauner
- Re: [TLS] Negotiate only symmetric cipher via cip… Dave Garrett
- Re: [TLS] Negotiate only symmetric cipher via cip… Daniel Kahn Gillmor
- Re: [TLS] Negotiate only symmetric cipher via cip… Dave Garrett
- Re: [TLS] Negotiate only symmetric cipher via cip… Daniel Kahn Gillmor
- Re: [TLS] Negotiate only symmetric cipher via cip… Andrei Popov
- Re: [TLS] Negotiate only symmetric cipher via cip… Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Negotiate only symmetric cipher via cip… Viktor Dukhovni
- Re: [TLS] Negotiate only symmetric cipher via cip… Dave Garrett
- Re: [TLS] Negotiate only symmetric cipher via cip… Daniel Kahn Gillmor
- Re: [TLS] Negotiate only symmetric cipher via cip… Ilari Liusvaara
- Re: [TLS] Negotiate only symmetric cipher via cip… Dmitry Belyavsky
- Re: [TLS] Negotiate only symmetric cipher via cip… Daniel Kahn Gillmor
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Geoffrey Keating
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Yoav Nir
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Viktor Dukhovni
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Geoffrey Keating
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Viktor Dukhovni
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Brian Smith
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Brian Smith
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Daniel Kahn Gillmor
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Salz, Rich
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Viktor Dukhovni
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Dave Garrett
- Re: [TLS] Negotiate only symmetric cipher via cip… Ilari Liusvaara
- Re: [TLS] Ala Carte Cipher suites - was: DSA shou… Yoav Nir