Re: bi-directional dining cryptographers

[stewarts@ix.netcom.com (Bill Stewart)]

At 12:24 PM 7/17/95 -0500, Phil Fraering wrote:
>I'd also like to point out that this system indicates that during
>an attack/disruption on a traditional dc-net, the disruptor can 
>tell what the original person was trying to send, even though noone
>else can.
>
>And then perhaps XOR the data with something offensive, and if the
>original sender tries to re-send, broadcast the result of the XOR,
>resulting in a total net output of the offensive material.

That's difficult - you have to identify that the sender is sending
the same message while the message is being sent, rather than
one or two bit-times later, and you can't fake encryption with an
unknown keyid or digital signatures.  (Digital signatures aren't
something everybody would use very often on a DC-net, since the purpose
of the net is to be anonymous, but since you can do anonymous broadcasts,
you can anonymously post a signature key for your nym if you want to.)

Also, there's no need to combine jamming and posting an offensive message;
they both work well separately.  I suppose you could do that if you only
want to harass the net a bit (e.g. replace all trafic to remailer X
with new remail to whitehouse.gov, or replace all postings from
Cancelmoose with complaints about censorship), but basically DCnets
degrade rapidly if the social structure of the net members does.
#                                Thanks;  Bill
# Bill Stewart, Freelance Information Architect, stewarts@ix.netcom.com