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Re: Digital Cash



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
[email protected]	     | 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 
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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)
>