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Re: Foiling Traffic Analysis
On Tue, 2 Jan 1996, Timothy C. May wrote:
> At 4:35 AM 1/2/96, Jon Lasser wrote:
>
> >The potential for traffic analysis is the danger here. If an "FBI
> >International Data Laundering Expert" testifies in court that said data
> >came from a site known to be frequented solely by so-and-sos, all the
> >strong crypto in the world won't stop the average jury from convicting you.
> >
> >Carl Ellison (among others, I'm sure) has suggested various means of
> >foiling traffic analysis among a group of trusted conspirators, using a
> >token-ring-like routing scheme. I'm not completely convinced that it's
> >robust enough, but a variation on it is probably adaptable.
>
> How does this differ from Dining Cryptographers approaches?
Totally different from a DC-Net, as far as I understand DC-Nets (I think
I do, but Applied Crypto's in my dorm, and I'm at home, so I can't check)
In this approach, computers are organized in "rings"; each computer in a
given ring always has an encrypted packet in circulation.
When the group of packets arrives at a given station, it replaces its
current encrypted packet with a new packet; if it doesn't have any new
packets to send, it puts up a garbage packet that is indistinguishable
from a normal packet. It then scans all the other packets and attempts to
decrypt them with its private key. Any it can read, it does; all the
packets are forwarded to the next station in the ring.
By the time the next set of packets arrives, all have been replaced; the
station is unable to determine either the source or the destination of
any given packet. Routing between loops is done by routers, which are
computers on multiple loops. Perhaps all machines are on multiple loops
and serve as routers.
I'm not sure about traffic analysis in cases where Mallet controls a
significant portion of the network; while this is unlikely, it must be
considered.
Any significant inconsistancies are probably mine...
Jon Lasser
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Jon Lasser <[email protected]> (410)494-3072
Visit my home page at http://www.goucher.edu/~jlasser/
You have a friend at the NSA: Big Brother is watching. Finger for PGP key.