Shortcut digital signature verification failure

[Lucky Green]

Bill wrote:
> I have been thinking about how to limit denial of service 
> attacks on a server which will have to verify signatures on 
> certain transactions.  It seems that an attacker can just 
> send random (or even not so random) data for the signature 
> and force the server to perform extensive processing just to 
> reject the transaction.
> 
> If there is a digital signature algorithm which has the 
> property that most invalid signatures can be detected with a 
> small amount of processing, then I can force the attacker to 
> start expending his CPU to present signatures which will 
> cause my server to expend it's CPU.  This might result in a 
> better balance between the resources needed by the attacker 
> and those needed by the server.

Neat idea. So neat in fact that RSA Security has a patent on it. :-)
Sorry, I don't have the patent number handy.

--Lucky


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