From: "Perry E. Metzger" <perry@imsi.com>
Date: Tue, 30 Aug 94 05:26:49 PDT
To: Jonathan Cooper <entropy@IntNet.net>
Subject: Re: e$ as "travellers check?
In-Reply-To: <Pine.3.89.9408291815.A23061-0100000@xcalibur>
Message-ID: <9408301226.AA12779@snark.imsi.com>
MIME-Version: 1.0
Content-Type: text/plain



Jonathan Cooper says:
> > > 	traveller's checks are an extremely easy way to defraud
> > > 	any bank that issues them,  what will happen to this
> > >  	difficulty factor if they are anonymous ?
> > 
> > Digitally signed notes are not forgeable.
> 
>    Right.
>   
>    I doubt very seriously that there is anything on the planet that is 
> *ABSOLUTELY* unforgable.   It all comes down to how much energy and 
> resources one is willing to sink into the project.

Sure, but if the resources are higher than the return there is no
economic incentive to do it. The trick is to keep the costs high
enough.

In the case of some public key problems, it is also possible to make
the cost of forgery impossibly high, in which case the attacker is
forced to try to physically steal the key or play similar games.

The question is not whether fraud will be attempted -- it will be
attempted. The question is whether we can lower it from a substantial
fraction of the cost of doing business to noise. If one's insurance
premiums against fraud drop to levels comparable to one's expenditures
on coffee filters for one's staff, then you know that you are in the
right ballpark.

Perry