臺灣博碩士論文加值系統

隨著 2008 年比特幣 (Bitcoin) 問世，區塊鏈技術逐年受到社會的重視，也啟發了許多區塊鏈技術的發展，而早在 1994 年就被提出的智能合約，也被以太坊 (Ethereum) 成功的將智能合約融入到區塊鏈系統裡，又將區塊鏈技術帶入了下一個紀元。

智能合約是現今區塊鏈技術最重要的特色之一，它可以讓使用者不需要中間人，即可和其他使用者交易金錢、財產或任何有價值的東西。相比於傳統合約，他可以省去大量的人力、時間以及資源，卻可以帶來更穩定也更安全的效益。

在以太坊問世之後，區塊鏈上的智能合約技術蓬勃發展，發展出非常多具有獨特價值的數位貨幣，因此也造成了有非常多的平行鏈，因此跨鏈的需求逐漸浮上檯面，本論文提供一個在面向小眾的區塊鏈，能在難度、成本與信任上達到最低限度的平衡下，達到跨鏈的資產交換的智能合約架構。

With the advent of Bitcoin in 2008, blockchain technology has been paid much attention to society every year and has inspired the development of many other blockchain technology. The idea smart contract, which was proposed in 1994, was successfully merged into Ethereum. It brings the development of blockchain technology into the next era.

Smart contract is one of the most important features in blockchain technology nowadays, which allows users to trade money, property of anything valuable without a middleman. Compared to traditional contracts, it can save a lot of manpower, time, and resources, but can bring more stable and more secure results.

After the advent of Ethereum, the development of blockchain-based smart contract flourished. There are many unique and valuable blockchain come out. However, every blockhain is parallel. It make the demand of cross-chain rising. This thesis proposes a cross-chain smart contract architecture that could connect most cryptocurrency and try to reach balance between difficulty, low-cost and trusty.

口試委員會審定書 i
Acknowledgments ii
摘要 iii
Abstract iv
List of Figures ix
List of Tables x
Chapter 1 Introduction 1
Chapter 2 Background 3
2.1 Transaction and UTXO . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Multi-signature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 OP RETURN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Chapter 3 Cross Chain Transaction 6
3.1 Multisig notary schemes . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Sidechains/Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Hash-locking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 4 Smart Contract 12
4.1 Smart Contract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Ethereum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 HyperLedger fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.4 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Chapter 5 Cross Chain Architecture Design 17
5.1 System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.2 Multi-signature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.3 Assumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.4 Work Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.4.1 Contract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.4.2 Deploy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.4.3 Invoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.5 Problem and solution . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.5.1 Pros and cons of the Architecture . . . . . . . . . . . . . . . . 24
5.5.2 Consensus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.5.3 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5.4 Contract Support . . . . . . . . . . . . . . . . . . . . . . . . . 25
Chapter 6 Case Study & Result 26
6.1 Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.1 Deploy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.2 Invoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.1.3 Multi-signature . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.2 Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.3.1 Difficulty on Implementation . . . . . . . . . . . . . . . . . . . 30
6.3.2 Application Scenario . . . . . . . . . . . . . . . . . . . . . . . 31
Chapter 7 Conclusion and Future Work 32
7.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2.1 Name Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2.2 Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2.3 Fee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7.2.4 Trust Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7.2.5 Invoke Contract in contract . . . . . . . . . . . . . . . . . . . 34
7.2.6 Consensus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7.2.7 Stress testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Bibliography 36

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