由於網際網路快速的發展，電子商務已深深影響了我們的電子體制系統，電子商務的出現讓人們在虛擬網路空間中進行購物成為可能。在這篇文章中，我們提出了一個更完善不可追蹤的電子票券協定，而我們的方法是根據陳維魁等人已提出的方法為基礎。電子票券交易的型態是一種新的付款模式，而且是離線交易即不需銀行介入。使用者先從銀行提領電子票券然後再付給指定的商店，商店隨後把此電子票券存入銀行。這方法看似可行，但仍有美中不足的問題需要克服；在使用者付款後一直到商店存款的過程中，商店和銀行為了將來方便檢查重覆付款之惡意行為，必須記錄所有已接受的電子票券，如此以致他們用以存放訊息之資料庫會超載過大。為了降低他們的負擔，我們在此系統中加了兩個參數，一個是序號（serial number）另一則是時戳（timestamp），這兩參數之設計不但可用來檢查重覆付款之惡行而且解決了資料庫會超載過大之問題。
在這篇文章中，我們也提出了一個在電子貨幣系統中之更完善代理存款系統，此系統是奠基於尤焙麟等人已提出之方法。在考慮大部分典型的電子貨幣系統中之關係，商店為了要存放從顧客付款之甲銀行發行的錢，他必須在此甲家銀行開一個帳號。因為在現實環境中有許許多多的銀行，所以每一家商店必須在每一家銀行中開一個帳號以便存放當收到不同家銀行所發行出來的錢。為了減少商店的負擔，我們將介紹存款授權協定之概念；即一家商店只需在他所信任的交易銀行（Acquirer）建一個帳户就可把所有之存款業務授權給他，由他來做後續清算動作。

Nowadays, due to the rapid growth of the Internet, it is convenient for cyber-shopping by using the exist electronic cash systems like as DigiCash[44], NetBill[46], E-Coin[45], NetCent[47], and CyberCash[43] etc. In this paper, we propose a refined untraceable electronic ticket protocol based on the scheme proposed by Wei-Kuei Chen et al.[8]. The scenario of electronic ticket (e-ticket) is a new payment model similar to an e-cash system but only able to be paid to the designated one. This model is suitable for many e-commerce models and it will be more efficient and economic to solve the double-spending problem.
In this paper, we propose a refined proxy deposit protocol based on the scheme proposed by Yu and Lei[34]. In consideration of the relationship in most typical e-cash scheme[3,7,10,11,15,18,20,22,23,25,26,27,28,33], a merchant must maintains an account at the issuer for depositing the received e-cash from customers. Since there will be a lot of issuers in the real world, each merchant must maintain an account at each issuer for depositing all kinds of e-cash. In order to reduce the onus of the merchants, the concept of deposit-delegation protocol will be introduced in this paper such that a merchant only has to maintain an account at its trading bank (as an acquirer) and delegates all deposit business to it.

Catalog
Abstract (in Chinese)--------------------------------------i
Abstract (in English)--------------------------------------ii
Acknowledgements (in Chinese)------------------------------iii
List of Figures--------------------------------------------vi
Chapter 1 Introduction------------------------------------1
1.1 Preliminary--- Origins of Money and of Banking-----1
1.2 Research Motivation--------------------------------2
1.3 Research Background--------------------------------4
1.3.1 Exist Electronic Payment Systems-------------4
1.3.2 How is Electronic cash (E-cash) Possible-----4
1.3.3 Ideal Electronic Cash System Requirements----5
1.4 Our Approach and Objectives -----------------------5
1.4.1 Primary Requirements of Electronic Cash System in
Our System-----------------------------------7
1.4.2 Primary Requirements of A Deposit Delegation
Protocol in Our System-----------------------7
Chapter 2 A Refined Untraceable Electronic Ticket Protocol for
Information Hiding------------------------------9
2.1 The Basic Concept of E-cash System-----------------9
2.2 Wei-Kuei Chen et al.’s Scheme---------------------10
2.3 Our Scheme-----------------------------------------12
2.4 Analysis-------------------------------------------15
2.4.1 No Forging-----------------------------------15
2.4.2 Untraceability-------------------------------15
2.4.3 Anonymity------------------------------------15
2.4.4 No Double-spending---------------------------16
2.4.5 Off-line Transaction-------------------------16
2.5 Conclusion-----------------------------------------16
Chapter 3 A Refined Proxy Deposit Protocol for E-cash Systems-- ------------------------------------------------17
3.1 A Naive Deposit Delegation Protocol----------------17
3.2 Yu and Lei’s Scheme-------------------------------17
3.3 Our Different Opinions-----------------------------19
3.4 Our Scheme-----------------------------------------20
3.5 Analysis-------------------------------------------22
3.5.1 No Damage From Intruder----------------------22
3.5.2 Non-repudiation------------------------------22
3.5.3 Fairness-------------------------------------23
3.5.4 Economy--------------------------------------23
3.5.5 Independence---------------------------------23
3.6 Conclusion-----------------------------------------23
Chapter 4 Conclusion--------------------------------------24
References-------------------------------------------------26
List of Figures
Figure 1. The relationship within an e-cash transaction-----5
Figure 2. A real situation within e-cash system-------------6
Figure 3. The untraceable electronic ticket protocol of Wei-Kuei Chen et al.--------------------------------------------10
Figure 4. The untraceable electronic ticket protocol of our scheme------------------------------------------------------14
Figure 5. A naive delegation protocol-----------------------17
Figure 6. The deposit delegation protocol of Yu and Lei-----18
Figure 7. The deposit delegation protocol of our scheme-----21

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