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Re: [Full-disclosure] Skype chat encryption with OTR

From: Tonnerre Lombard (tonnerre.lombardsygroup.ch)
Date: Fri Jun 20 2008 - 01:46:33 CDT


Salut, JM,

On Thu, 19 Jun 2008 08:55:01 -0500, JM wrote:
> Actually, the shared keys are *published* once they're discarded to
> improve plausible deniability. That lets anyone forge an *old*
> message, but ensures you wont' accept a forged message during the
> course of the conversation.

Oh, hm, right. But either way, the plausible deniability is provided
only by that mechanism, not through changing the keys after each
message. That's only the mechanism used to recover the security of the
algorithm after key disclosure. It's the typical cryptographic type of
proof if authenticity which is executed in a way which is only ever
trustworthy to the recipient, so the recipient cannot prove anything to
others with it.

                                Tonnerre
--
SyGroup GmbH
Tonnerre Lombard

Solutions Systematiques
Tel:+41 61 333 80 33 Güterstrasse 86
Fax:+41 61 383 14 67 4053 Basel
Web:www.sygroup.ch tonnerre.lombardsygroup.ch

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