Re: [tcpm] PoC for draft-moncaster-tcpm-rcv-cheat-02

Bob Briscoe <rbriscoe@jungle.bt.co.uk> Fri, 28 March 2008 01:25 UTC

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Date: Fri, 28 Mar 2008 01:25:10 +0000
To: Rob Sherwood <capveg@cs.umd.edu>
From: Bob Briscoe <rbriscoe@jungle.bt.co.uk>
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Subject: Re: [tcpm] PoC for draft-moncaster-tcpm-rcv-cheat-02
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Rob,

Just to be clear, our original aim was merely to put what you had 
done into IETF standards-speak because we believed you (and previous 
researchers on the same tack) had identified a serious vulnerability 
and a reasonable solution. However, on writing up the I-D, we quickly 
realised the TCPM w-g would likely have issues with some of the 
precise details of your approach, so we ended up inventing a slightly 
different but broadly similar approach.

It's been fairly closely scrutinised technically on the list. I think 
we have satisfied most people that a 'good' solution is possible that 
has no harmful side-effects - at least in theory.

You're right that we haven't simulated or implemented the deltas from 
your approach. This was originally a sideline activity - just a write 
up that turned into more than we had planned. Nonetheless, Toby 
Moncaster (the primary author) now has plans to simulate it and write 
up the outcome. I can't be more precise 'cos I'm responding on his 
behalf, as he's on his sick-bed at the mo. I guess if it became a WG 
item, he'd get simulations done sharpish.


Bob


At 19:33 26/03/2008, Rob Sherwood wrote:
>My take on this issue is that people are
>divided into three[1] camps:
>---snip---
>c) people who believe this attack is practical and dangerous, but felt
>         my randomly-skipped segments solution was not "good" for
>         reasons of efficiency, correctness, etc.
>---snip---
>But that still leaves
>the bottleneck on people in group (c) to come up with a "good"
>solution.  Bob Briscoe et al. have come up with a variant on my
>solution, but I am not certain how well its been scrutinised or if it
>has even been implemented.



____________________________________________________________________________
Notice: This contribution is the personal view of the author and does 
not necessarily reflect the technical nor commercial direction of BT plc.
____________________________________________________________________________
Bob Briscoe,                           Networks Research Centre, BT Research
B54/77 Adastral Park,Martlesham Heath,Ipswich,IP5 3RE,UK.    +44 1473 645196 


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