Browsing by Author "Fan, CI"

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Date attachable electronic cash
(2000-02-15)
Fan, CI
;
Chen, WK
;
Yeh, YS
;
資訊工程學系
;
Department of Computer Science
In this paper we propose a new untraceable electronic cash scheme which makes it possible for a payer to attach the desired date to his electronic cash during a transaction. With the aid of the date attachability property, the date on which an electronic cash is deposited in the bank cannot be forged in an electronic cash scheme. It is conducive to the unforgeability of the number of days for which the cash has been stored in the bank for some necessary purposes such as interest calculation. Our scheme not only keeps the attached date from being forged but also avoids two or more different dates being attached to the same electronic cash. Furthermore, the date attachment does not affect the untraceability property of electronic cash. Comparing with typical electronic cash schemes, the extra computation required for date attachment is just hashing. (C) 2000 Elsevier Science B.V. All rights reserved.
Randomization enhanced Chaum's blind signature scheme
(2000-11-01)
Fan, CI
;
Chen, WK
;
Yeh, YS
;
資訊工程學系
;
Department of Computer Science
At Crypto'99 Dr Coron, Naccache, and Stern presented a signature forgery strategy of the RSA digital signature scheme. The attack is valid on Chaum's blind signature scheme, which has been applied to many practical applications such as electronic cash and voting. In this paper we propose a method to inject a randomizing factor into a message when it is signed by the signer in Chaum's blind signature scheme such that attackers cannot obtain the signer's signatures of the: special form for the attack. (C) 2000 Elsevier Science B.V. All rights reserved.