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So has anyone tried to solve the problem of double spending and the online requirement of digital cash? It seems digitial cash is really only digital "check" right now as it must be verified at the bank before it can be show to be "valid." Is there any way to take cash offline? Or is this merely the copy protection problem rehashed? -uni- (Dark)
In _Applied Cryptography_ by Bruce Schneier, he refers to a system proposed by Tatsuaki Okamoto and Kazuo Ohta that meets the following criteria: Independance. The security of the digital cash is not dependant on any physical location. The cash can be transfered through a computer network. Security. The digital cash cannot be coppied and reused. Privacy (untraceability). The privacy of the users is protected; no one can trace the relationship between users and their purchases. Off-Line Payment. When a user pays for a purchase with electronic cash, the protocall between the user and the merchant is executed off-line. Transferability. The digital cash can be transfered to other users. Divisability. A piece of digital cash in a given amount can be subdivided into pieces of cash in smaller amounts. The reference given for this paper is as follows: T. Okamoto and K. Ohta,"Universal Electronic Cash," Advances in Cryptology--CRYPTO '91 Proceedings, Berlin: Springer-Verlag, 1992, pp. 324-337 Happy Hunting, -Chris. ______________________________________________________________________________ Christian Douglas Odhner | "The NSA can have my secret key when they pry cdodhner@indirect.com | it from my cold, dead, hands... But they shall pgp 2.3 public key by finger | NEVER have the password it's encrypted with!" cypherpunks WOw dCD Traskcom Team Stupid Key fingerprint = 58 62 A2 84 FD 4F 56 38 82 69 6F 08 E4 F1 79 11 ------------------------------------------------------------------------------ On Tue, 3 May 1994, Black Unicorn wrote: > > So has anyone tried to solve the problem of double spending and > the online requirement of digital cash? > > It seems digitial cash is really only digital "check" right now as > it must be verified at the bank before it can be show to be "valid." > > Is there any way to take cash offline? Or is this merely the copy > protection problem rehashed? > > -uni- (Dark) >
On Tue, 3 May 1994, Black Unicorn wrote: > So has anyone tried to solve the problem of double spending and > the online requirement of digital cash? Sure. Stay jacked-in full time. Seriously, communications costs are dropping so fast, I'm not sure why you'd put much effort into designing a bulletproof offline system. Even with today's technology, a shopkeeper could just have a $17.50/mo. Netcom account and run his Magic Money client whenever someone wanted to pay with bits. Certainly no more expensive than a credit card Verifone. But this question comes up often enough that I'm afraid I'm missing something. Why would offline systems be more useful? Joe
> > But this question comes up often enough that I'm afraid I'm missing > something. Why would offline systems be more useful? Anonymity. Digital Cash, in theory, works like Federal Reserve Notes. Financial transactions can be carried out between individuals with out a bank as an intermediary. Therefore, there is no record of the transaction. One doesn't have to smear one's fingerprints all over cyberspace to buy a used bicycle for their child or pay off a Super Bowl bet. -- PGP PUBLIC KEY via finger! JAFEFFM Speaking & Thinking For Myself! * eagle@deeptht.armory.com email info@eff.org * *** O U T L A W S On The E L E C T R O N I C F R O N T I E R **** ***** Committed to Free Public Internet Access for World Peace *****
Jeff Davis says: > > > > But this question comes up often enough that I'm afraid I'm missing > > something. Why would offline systems be more useful? > > Anonymity. Online systems are also guaranteed anonymous. The whole point of offline transactions is just to eliminate the need to be online, which can be inconvenient -- as an example, if you are trying to buy something on a streetcorner or otherwise away from telecom. In the future, this will not be so much of a problem. For the moment its quite interesting. Perry