Re: [TLS] TLS renegotiation issue
Martin Rex <mrex@sap.com> Thu, 05 November 2009 19:29 UTC
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From: Martin Rex <mrex@sap.com>
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To: Nicolas.Williams@sun.com
Date: Thu, 05 Nov 2009 20:29:28 +0100
In-Reply-To: <20091105184615.GG1105@Sun.COM> from "Nicolas Williams" at Nov 5, 9 12:46:15 pm
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Cc: ekr@rtfm.com, tls@ietf.org
Subject: Re: [TLS] TLS renegotiation issue
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Nicolas Williams wrote: > > Initial comments based on a brief skim: > > - Please add a normative reference to RFC5056. I admit to not know what that exactly means, but it sounds wrong. It is perfectly possible to write this document in a fashion that an implementor does NOT NEED to read rfc5056, and therefore I would strongly prefer to keep it that way. > > - There's no real need for the ServerHello to include both of the > Finished messages from the outer TLS connection. (I think there's no > real need for the ServerHello to include either of them, actually, > but I've not thought enough about that.) But it's OK as is, of > course. The Server should send back something different than on initial connect in order to indicate to the client that it is convinced this is a renegotiation rather than an initial handshake. Sending back the verify_data from Server finished seems fair to me. > > - You call for each TLS handshake to bind to the one immediately > outside it. > > Would it be better to bind to the outer-most one instead? I prefer it the way it is currently described, referencing the predecessor. > > (In practice there's probably never more than one outer and one inner > handshake, right?) Technically, there can NEVER be more than two, as required by the TLS spec (there is only one current and one pending) so technically, the existing proposal is referencing the "outer-most" TLS session. You were probably asking for the first TLS-handshake on a connection? The existing proposal looks like less code to me. > > - There is a way for clients to protect themselves even when servers > don't implement this extension: I would hope there is a way, but I have not seen one so far! There are actually two different scenarios: the one I suggested where both sides, client and server perform a renegotiation, and the one described by Marsh, where a clients initial TLS handshake is proxied into a renegotiation for the server. Without a change of the server, the client has certain difficulties to determine whether it is participating in an initial TLS handshake or being proxied into a renegotiation in Marsh's scenario. There are certain safeguards a client can apply (but which are not currently advised by the spec, so are unlikely to be implemented in existing clients. A TLS client could insist on a server credential to not change during a renegotiation. That helps for my scenario, but not for that of Marsh. A TLS client should probably not accept a HelloRequest and neither a CertificateRequest message on a server-anonymous TLS session (DH_anon). > > - Might as well update RFC5246 to indicate that the Finished messages > for any connection MUST be exported to applications. Better get this > done now. I haven't sufficiently thought about this to like it. Adding the finished messages to the renegotiation handshake is fine, because they have originally exchanged under the protection of the currently active ciphersuite, so this should have zero impact. You're asking to make something available that has not been previously available to the application. This might be harmless, but I don't know. -Martin
- [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Florian Weimer
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Michael D'Errico
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Florian Weimer
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- [TLS] TLS or HTTP issue? (was: TLS renegotiation … Nikos Mavrogiannopoulos
- Re: [TLS] TLS renegotiation issue Yngve N. Pettersen (Developer Opera Software ASA)
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Cullen Jennings
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Michael Gray
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS or HTTP issue? Florian Weimer
- Re: [TLS] TLS or HTTP issue? Bruno Harbulot
- Re: [TLS] TLS renegotiation issue Blumenthal, Uri - 0662 - MITLL
- Re: [TLS] TLS or HTTP issue? Peter Saint-Andre
- Re: [TLS] TLS or HTTP issue? Martin Rex
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Nicolas Williams
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Nathaniel W Filardo
- Re: [TLS] TLS or HTTP issue? Marsh Ray
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Nicolas Williams
- [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Michael D'Errico
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Robert Relyea
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Michael D'Errico
- Re: [TLS] TLS or HTTP issue? Dean Anderson
- Re: [TLS] TLS renegotiation issue David Harrington
- [TLS] To API or not (Re: TLS renegotiation issue) Nicolas Williams
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Marsh Ray
- [TLS] Simple way to drop re-negotiation in HTTP (… Nicolas Williams
- Re: [TLS] TLS renegotiation issue Michael D'Errico
- Re: [TLS] TLS renegotiation issue Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate.txt Martin Rex
- Re: [TLS] Simple way to drop re-negotiation in HT… Marsh Ray
- Re: [TLS] TLS or HTTP issue? Nikos Mavrogiannopoulos
- Re: [TLS] TLS or HTTP issue? Marsh Ray
- Re: [TLS] TLS renegotiation issue Michael D'Errico
- Re: [TLS] TLS renegotiation issue Marsh Ray
- Re: [TLS] TLS or HTTP issue? Michael D'Errico
- Re: [TLS] Test Server (was TLS renegotiation issu… Michael D'Errico
- Re: [TLS] Test Server (was TLS renegotiation issu… Michael D'Errico
- Re: [TLS] TLS renegotiation issue Nagendra Modadugu
- Re: [TLS] TLS renegotiation issue Eric Rescorla
- Re: [TLS] TLS or HTTP issue? Nicolas Williams
- Re: [TLS] TLS renegotiation issue Nicolas Williams
- Re: [TLS] TLS or HTTP issue? Florian Weimer
- Re: [TLS] Simple way to drop re-negotiation in HT… Nicolas Williams
- Re: [TLS] TLS or HTTP issue? Chris Newman
- Re: [TLS] TLS or HTTP issue? (was: TLS renegotiat… Chris Newman
- Re: [TLS] TLS renegotiation issue Bodo Moeller
- Re: [TLS] TLS or HTTP issue? Nikos Mavrogiannopoulos
- [TLS] Comments on draft-rescorla-tls-renegotiate Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Martin Rex
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nicolas Williams
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Nelson B Bolyard
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… David-Sarah Hopwood
- Re: [TLS] Comments on draft-rescorla-tls-renegoti… Bodo Moeller