Re: [TLS] Abbreviated Handshake != Renegotiated Handshake
David-Sarah Hopwood <david-sarah@jacaranda.org> Sun, 20 December 2009 00:29 UTC
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Sender: David-Sarah Hopwood <djhopwood@googlemail.com>
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Date: Sun, 20 Dec 2009 00:29:15 +0000
From: David-Sarah Hopwood <david-sarah@jacaranda.org>
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Subject: Re: [TLS] Abbreviated Handshake != Renegotiated Handshake
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Ravi Ganesan wrote: > David-Sarah Hopwood wrote: >> Ravi Ganesan wrote: >> >>> I know everyone on this thread knows otherwise, but the way the terms get >>> used, can easily result in confusion between "full handshake", >> "abbreviated >>> handshake" and "renegotiated full handshake". The attack only applies of >>> course to last category, and NOT to the abbreviated handshake. >> Well, it also applies to a renegotiated abbreviated handshake (where a >> renegotiating handshake resumes an existing session). The spec should >> probably point out that this case is possible, and that exactly the same >> attacks and defences apply. > > This may be my ignorance, but I assumed the purpose of renegotiation was a > fresh exchange of authentication and/or keying material. The renego for > instance can (infamously) require client-auth while the original did not. Or > switch ciphersuites. > > The abbreviated handshake cannot achieve any of this. Yes it can; a renegotiation with an abbreviated handshake using the same session ID as the previous handshake, has the effect of refreshing keys. > But regardless even if there is something in existence called a > "renegotiated abbreviated handshake", I think the distinction between > 'abbreviated handshakes without renegoitation' which are very very widely > used should not be confused with 'renegotiated handshakes of any kind'. > > It would be very helpful if the draft made this point. As long as it does so in a way that doesn't add further confusion, yes. -- David-Sarah Hopwood ⚥ http://davidsarah.livejournal.com
- [TLS] Abbreviated Handshake != Renegotiated Hands… Ravi Ganesan
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Marsh Ray
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Ravi Ganesan
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Michael D'Errico
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Eric Rescorla
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Ravi Ganesan
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Michael D'Errico
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Martin Rex
- Re: [TLS] Abbreviated Handshake != Renegotiated H… David-Sarah Hopwood
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Ravi Ganesan
- Re: [TLS] Abbreviated Handshake != Renegotiated H… Martin Rex