On Mon, Mar 10, 2003 at 10:24:45AM -0800, Hallam-Baker, Phillip wrote:
But consider what happens when you use mobile code to describe the
hash function. You can respond to the circumvention techniques as
the spam senders apply them.
This is how satelite TV companies keep card piracy at acceptable levels.
PThey don't shut off a pirate card immediately, they let a number
of customers develop then they kill it when doing so does maximum
damage to the pirate's reputation.
That's exactly the point why it won't work:
TV companies:
Many attackers, few defenders only. It's like dogs hunting the
rabbit. The rabbit can react on the moves of the dogs and
can rapidly change it's way, run zigzag, and so on, because it
can immediately change it's running direction without discussion.
Spam:
Few attackers, many defenders. It's like a shark in a cluster
of fishes. The rabbit's defense method will fail for the fishes.
That's why adaptive hash techniques requiring the defenders to
change their "secret formula" or to upgrade their software
continuously are doomed to fail. Sorry.
Hadmut
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