-- more on -- blackmail / real world stego use

[Dave Farber <dave () farber net>]

> From:
>
> (If you decide this is worth forwarding, please attribute to "Anonymous"
> and cut out my e-mail.  I'm not much on spam, and I don't need a
> thousand responses from ticked off cypherpunks criticizing my admittedly
> general explanation, either.)
>
> Mr. Farber--
>
> This scheme is not unlike one that could be used quite effectively with
> naive anonymous cash protocols based on blind digital signatures.
>
> In case you're not totally familiar with digital cash protocols, here's
> how they work (just a rough overview; enough to explain the problem):
>
>         1. A user wishing to withdraw X dollars from his bank Y generates 
> 100 messages, each with a unique ID, stating that "This message can be 
> exchanged for X dollars in cash at bank Y".
>         2. The user then "blinds" each message so that it can't be read 
> without a key.
>         3. The user then sends the blinded messages to bank Y, who 
> selects one message at random and demands that the user send the 
> information needed to "unblind" the other 99.
>         4. The user complies, and the bank verifies that each unblinded 
> message has the same amount.  When the bank is satisfied that this is 
> true, it signs the remaining (blinded) message and sends it back to the 
> user, transferring X dollars out of the user's account and into holding 
> at the same time.
>         5. The user unblinds the message to obtain his signed bank check 
> worth $100.  Since the bank never learned the unique ID, it can't be 
> traced to any of his transactions with the bank.
>
> Anyway, the basic idea behind this scheme is pretty close to what the
> Dutch gentleman is accused of having done.
>
>         1. Kidnap a child or threaten to do something nasty (e.g., poison 
> products)
>         2. Demand, as ransom, that a bank sign a number of blinded 
> messages, with an aggregate value of $10000.00, and publish the results 
> in the New York Times.
>         3. Read the messages, unblind them, and-- voila-- $10000.00 in
> anonymous, untraceable digital cash.  Now feel free to release the kid
> or  refrain from tampering with Tylenol bottles.
>
> Just an interesting parallel.  The guy used difficult-to-trace (though not 
> completely anonymous) cash systems, a public forum for the transfer of the 
> fund information, and a serious enough threat to actually get his demands met.
>
> Kind of a neat way to do things.

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