---------- Forwarded message ---------- From: Мария Коростелёва <[email protected]> Date: 2013/11/28 Subject: Re: [OTR-dev] Ensuring transcript soundness in a multiparty chat setting To: Trevor Perrin <[email protected]>
2013/11/28 Trevor Perrin <[email protected]> > On Thu, Nov 28, 2013 at 8:29 AM, Мария Коростелёва > <[email protected]> wrote: > > Hi everyone, > > > > I have a question considering the topic of this converstion. > > > > If we have a situation like this: > > > >>> At some point t_0, it so happens that A and B each send a message (m_a > >>> and m_b) to all other participants at approximately the same time [0]. > >>> At t_0, the internal transcript state of A, B and C is the same. > >>> > >>> When C receives m_a, the consensus check matches and C updates her > >>> internal transcript state to include m_a. > >>> Now, when C receives m_b, the consensus check won't match since the > >>> internal transcript state of C includes m_a, while the consensus check > >>> of m_b doesn't (B was not aware of m_a when m_b was sent and hence it > >>> was not included in its consensus check). > >>> > >> That's OK. m_b's consensus check doesn't have to include every > >> message in C's transcript, it just has to be consistent with C's > >> transcript. Which it is! > > > > how exactly C checks the consistency of m_b's consensus check? > > Every message will state what its "predecessors" are. > So when C receives m_b, C will know that m_a is not a predecessor of > m_b. Thus C will not include m_a when checking m_b's consensus hash. > This approach reminds me more about OldBlue, than the algorithms described in papers [0] and [1], that were mentioned in the first letter. What's the difference? > > Agreed this isn't explained well. Maybe a wiki with an algorithm > description would help? > They sure will :) > > > Trevor > [0]: http://www-users.cs.umn.edu/~hopper/gotr.pdf [1]: http://matt.singlethink.net/projects/mpotr/oldblue-draft.pdf Maria
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