Micropayments, redux

[Zully Ramzan]

There are a number of ways to deal with some of the objections that have
come up in this thread; e.g. the unlucky user scenario. 

Refer to the paper "Micropayments Revisited" written by Silvio Micali
and Ron Rivest:  
http://theory.lcs.mit.edu/~rivest/publications.html    

[The powerpoint slides are also quite useful.]

The schemes in this paper combine Payword (Rivest and Shamir) with the
Lottery Ticket proposal (Rivest).  They also introduce a number of other
neat ideas.  As of the last time I talked to Ron and Silvio about it,
the Peppercoin scheme is based on these techniques.   

Regards,

Zully   

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Zulfikar Ramzan
IP Dynamics, Inc.   http://www.ipdynamics.com
Secure, Scalable Virtual Community Networks
 

> -----Original Message-----
> From: David Wagner [mailto:daw at mozart.cs.berkeley.edu]
> Sent: Monday, December 16, 2002 4:47 PM
> To: cryptography at wasabisystems.com
> Subject: Re: Micropayments, redux
> 
> Matt Crawford  wrote:
> >> No, it doesn't.  It doesn't take unlimited time for lottery-based
> >> payment schemes to average out; finite time suffices to get the
> >> schemes to average out to within any desired error ratio.
> >
> >Strictly speaking, the average will come within your error tolerance
> >of the expected value *with probability near 1*.
> 
> Yes, but the probability of it being significantly worse than I
claimed
> (i.e., by more than a factor t) is exponentially small (in t).  One
can
> easily calculate concretely exactly what the risk curve looks like.
> I'll spare everyone the details and just say that I see no reason why
> this should be a showstopper in practice.
> 
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