Spam article in SciAm

There is an interesting article in April's Scientific American on Spam.
It discusses Bayesean filters as well as a modification I've seen discussed here which creates terms not by spaces,
but by overlapping characters, which aparently works well with asian text as well as html encoded hacks.
i.e.

"click here"  becomes the terms


<sp>cli
clic
lick
ick<sp>
ck<sp> h
...


They didnt give details about how many characters or ajacent terms etc but say Microsoft is experimenting with this technology.

The other interesting idea presented I had never heard of before was a computation challenge/response system, the idea
is that if a non-whitelisted email arrives, to send back a challange where the sender has to compute some expensive function.
( ideally a function that an actual person could compute trivially but also something that can be automated).
The idea is to make sending spam computationally expensive while making sending good email non-computationally expensive.

There was another scheme proposed which required a deposit into a global bank where if people received spam they could
extract micropayment from the sender, but if it was good then you dont extract payment.
( Presumably even if they did it would be a small amount, say 1 cent).
Again, the idea being to make sending spam expensive, while sending good email cheep.

-----------------------------------------------------------
David A. Lee
[email protected]  
http://www.calldei.com


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