A Renewable E-Coin Scheme with a Third-Party Issuer

• Main Authors: Chih-Ming Lin, 林志明
• Other Authors: Lih-Chyau Wuu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/71640097091396845293

碩士 === 國立雲林科技大學 === 資訊工程研究所 === 93 === In this dissertation, we propose an efficient on-line e-coin system which achieves circulation of e-coins. The proposed system has four parties: Consumer, Merchant, Bank and Issuer, and two operating modes: basic mode and enhanced mode. It is essential to have a trustworthy Issuer in the basic mode, but the enhanced mode applies the hash chain technique to conquer the assumption that Issuer must be honest. In our system, an e-coin is generated by its owner and consists of a secret value, c, and a public value, c''=h(c), where h() is a secure one-way hash function. The public value of an e-coin is published by Issuer (delegated by Bank) on his bulletin board in withdrawal phase. Instead of Bank, Issuer has to be on-line to verify and renew e-coins during payment phase. That is, Issuer replaces the public values of Consumer''s e-coins with Merchant''s ones denoting the amount of money which must be paid in a transaction. Such a replacement is called as renewal and that makes the coin can circulate among users. Both of the communication bottleneck and the storage overhead occurring in Issuer can be distributed by using different bulletin boards of several Issuers. Besides, different bulletin boards can be used to represent e-coins of various denominations. With the features of renewal and various denominations, not only e-coin can circulate among users but Merchant has the capability to give change to Consumer.