Hamiltonian path as protection against DOS.

Adam Back adam at cypherspace.org
Mon Aug 14 17:31:39 EDT 2006

On Mon, Aug 14, 2006 at 12:23:03PM +1000, mikeiscool wrote:
> But you're imaging an attack with a distributed bot net DDoS'ing you,
> correct? Couldn't they then also use their botnet to process the
> messages faster then normally? They already have the computering
> power. Just a minor addon to the bot client app.

If you're using a hashcash token which takes 20 seconds of your CPU,
it'll slow the spammer down if they owned node has broadband.

(Think about 5k message size, multiple Bcc recipients etc; the spammer
of an owned botnet node can send multple many per second if hashcash
reduces the number of messages that can be sent by a factor of 100,
thats a good thing.)

Whether its enough of a slow down is an open question -- but I think
its difficult to imagine a security protocol that prevent spam with
the attacker owning some big proportion of nodes.


> Or if it is many requests from one or thousands of clients, can you
> not, per host, ask them to use a cached version? Per X timeout.
> Of course, you can't do this with SSL, though.

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