Shortcut digital signature verification failure

[Pete Chown]

Ed Gerck wrote:

> A
> scalable strategy would be a queue system for distributing load to
> a pool of servers and a rating system for early rejection of repeated
> bad queries from a source.

You could also vary the amount of hashcash required depending on the
number of bad signatures you are receiving.  So normally you would
require no hashcash, so the clients don't have to expend CPU cycles. 
Then as the number of bad signatures increases, you step up the amount
of hashcash so that you can continue coping.

Interestingly you ought to be able to calculate the amount of hashcash
required to keep the flow of bad signatures manageable.  Suppose your
current hashcash requirement is x, and bad signatures are arriving at
twice the speed your crypto accelerator can cope with.  Then, assuming
that the hashcash calculation is the dominant cost for the attackers,
you need to double your requirement to 2x.

-- 
Pete


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