Bitcoin Forum

Does anyone here have an intimate knowledge of Faircash?  (http://faircash.org/home.html) From what I can tell, it's a central bank for a cryptographic token based digital currency.

First time I seen it, I don't know anyone accepting it at all.

Kind of like a patented, closed-source, privately managed version of what anyone else can do using open source nowadays (including with Open Transactions)?:
 - http://en.bitcoin.it/wiki/Open_Transactions

Currently reading the creator's dissertation, and encountered this gem...

"Following the cash paradigm, it needs to be done peer-to-peer and offline in a repeatable way. Such a transfer is called teleportation. The main technical problem is to guarantee fairness under all circumstances. The fundamental effect of the Byzantine Generals’ undecidability state issue (see page 57) does not allow conducting such a transfer without a (trusted) third party. This fact seems to contradict the offline attribute of the aspired cash transfer. To the author’s knowledge, there has not been any treatment of this challenging problem, neither in the practical field nor in the literature over the last 10 years.[/b]"

It appears that this person, likely German born and a graduate student in California, has been researching the academic media available on the subject of digital currencies, and managed to completely overlook Bitcoin during the past two years.  Poor bastard, I hope that he managed to complete his degree, at least.

My initial impression of the protocol, as explained in the dissertaition, is that it's much like the exchange of cryptographic tokens over a ssh connection directly between peers, as well as a digital receipt of said transaction, with a built in mediation system upon the breakdown of honesty.  Based upon that limited initial impression, I can think of a number of ways to screw with the system that wouldn't work with bitcoin, mostly modified web-of-trust attacks.

fairCASH seems very similar to the (now defunct) eCash... http://en.wikipedia.org/wiki/Ecash
Email them, and ask them how they differ from eCash  ;)

I don't think off-line transactions would work without a considerable degree of external enforcement. Correct me if I'm wrong, but the extent that Chaum's (and others') scheme can manage double-spend is that the spender's identity may be revealed when it's discovered. Otherwise, there isn't enough information available to connect two distinct transactions to a single spender. After that, it's up to centralized management to deal with it. Maybe you always hold some collateral at the user's account. Maybe you involve the police. That's the extent it works.

That's why I think it's not more feasible than on-line transactions. You can create a similar regime built on top of Bitcoin, where addresses are signed and guaranteed by an authority that keeps collateral (or ID information). When an off-line double-spend occurs, the authority can manage the situation.

Are there any advantages of Faircash in this context that I might have overlooked?

(edited for clarification)