臺灣博碩士論文加值系統

部署在區塊鏈上的智能合約意味著不可改變；然而在不同的時間點，各方在實作的過程中，實作的方向跟內容可能會有改變。例如，修復安全問題，因此合約需要被調整或修改。我們提出了一種基於狀態的智能合約框架，可以讓合約順利被修改，已部署的智能合約可以部分地更新邏輯，同時保持先前的狀態一致。
具體來說，我們將普通合約劃分為四種不同類型的合約，在框架中合約分別負責不同部分。控制合約使用有限狀態機管理控制邏輯，其中狀態受版本控制保護以區分合約的不同版本；儲存合約會負責儲存不同使用者每一個狀態下的全域變數；主要合約實作應用邏輯的主要部分；更新契約實作以基於狀態的方式設計的程式碼，如此會比較容易更新合約內容。
並且，我們已經實施了概念驗證保險智能合約，如何在此框架下開發、部署、執行和更改可修改的智能合約。

A smart contract deployed on the blockchain is meant to be immutable; however, in practice, the consensus and operations among parties may change as time goes by, e.g., to fix security frauds, leading to the need of flexibility on contract modification. We propose a state-based smart contract framework that facilitates contract modification, where a deployed smart contract can be altered partially with update operations or control logic while keeping previous transactions (blocks) consistent.
Specifically, we divide an ordinary contract into four functional contracts that are linked by the framework to work together. The control contract manages the control logic with a finite state machine where transactions are guarded with version control to distinguish different versions of the contract; the storage contract that accesses global variables synchronizes the view of state variables; the main contract implements the main part of application logic, and the update contract implements codes that are designed in a state-based fashion to allow to be swapped with update operations.
We have implemented a proof-of-concept insurance smart contract to demonstrate how to develop, deploy, execute and alter a modifiable smart contract under the proposed framework.

第一章 Introduction 1
第二章 Related Work 4
第一節 Background: Blockchain 4
第二節 Background: Smart Contract 5
第三節 Background: Smart Contract Language 6
第四節 ERC-54 Upgradable Smart Contract (USC) 7
第五節 Upgradeable Smart Contract Structure 8
第六節 Upgradeable Smart Contracts by CMC 9
第三章 Modifiable Smart Contract 11
第一節 Overview 11
第二節 An Ordinary Smart Contract 14
第三節 State-based Contract 16
第四節 Control Contract 17
第四章 Implementation 18
第一節 Implementation of Control Contract 19
第二節 Implementation of Storage Contract 22
第三節 Implementation of Main Contract 23
第四節 Implementation of Update Contract 24
第五章 Modification Scenario 25
第一節 Change the Application Logic 26
第二節 Add a New Function 26
第三節 Add a new Storage 28
第四節 Case Study: Annuity Insurance 29
第六章 Threat Model 33
第一節 Unauthorized Modifiaction to Smart Contract 33
第二節 The Bad Design the FSM 34
第七章 Discussion 34
第一節 Storing Global Vriables 34
第二節 Generic Programming 35
第三節 Cost Issues 35
第四節 Compare to Other Modifiable Smart Contract 35
第八章 Conclusion 38
第九章 References 40

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