近年虛擬貨幣交易逐漸受到市場注目，新穎的貨幣標的與提供投資者貨幣交易管道的交易所不斷出現在市場上，全世界都在關注著虛擬貨幣瞬息萬變的投資市場，熱錢大量湧入讓使用者帳戶資產不斷上漲，帳戶安全也因此成了投資者所關注的課題。
    本論文將針對幾種常見的私鑰的保存方式做討論，隨著近年DeFi逐漸流行，去中心化的交易所市占率不斷提升，人們選擇自保管私鑰的比率也隨之提高，本研究將從分散式系統的架構下探討使用者的私鑰在分散式環境下保存的安全性，同時透過分散式系統協助使用者的私鑰在遺失時可以成功的還原回來。於分散式的環境中討論防範加密機制與設置混淆訊息來抵禦潛在的攻擊者以及維護使用者資料安全性及資料整體性，有助於提升私鑰保管的安全。
	在實作中透過四台電腦與八台電腦分別進行私鑰的加密與分散儲存，並進行安全性討論，以及架構延伸的探討。在實作中，儲存階段可以防範潛在的攻擊者意圖竊取使用者完整私鑰，於還原階段也可以協助使用者將遺失的私鑰還原，顯示透過分散式系統對於使用者私鑰保存有正面的幫助。

This paper will discuss several common ways of storing private keys. With the increasing popularity of DeFi in recent years, the market share of decentralized exchanges has continued to increase, and the rate of people choosing to keep private keys by themselves has also increased. This research will explore the security of the user's private key stored in a distributed environment and at the same time assist the user's private key to be successfully restored when it is lost through the distributed system. Discuss preventing encryption mechanisms and setting up obfuscated messages in a distributed environment to resist potential attackers and maintain user data security and data integrity, which helps to improve the security of private key custody. In the implementation, the storage phase can prevent potential attackers from attempting to steal the user's complete private key. During the restoration phase, it can also assist the user in restoring the lost private key, showing that the distributed system has a positive effect on the user's private key.

目錄
第一章前言1
1.1 研究動機1
1.2 論文架構2
第二章背景知識4
2.1 區塊鏈介紹4
2.2 區塊鏈架構5
2.2.1MerkleTree6
2.2.2交易，挖礦與產生新區塊8
2.2.3區塊鏈加密機制10
2.3 以太坊12
2.3.1智能合約13
2.3.2 DApp16
2.4 虛擬貨幣託管18
2.4.1 遺失貨幣研究18
2.4.2中心化的交易所20
2.4.3第三方託管23
2.4.4去中心化的交易所24
第三章研究方法27
3.1問題陳述27
3.1.1私鑰託管(儲存)27
3.1.2私鑰遺失28
3.2架構29
3.2.1私鑰儲存30
．分割私鑰31
．加密私鑰片段31
．分散儲存加密後的私鑰片段32
3.2.2私鑰還原33
．身分驗證34
．伺服器取回加密私鑰片段35
．解密被加密之私鑰片段35
．重組解密後的私鑰35
第四章 研究結果37
4.1儲存之實驗結果37
4.1.1以四台電腦進行儲存之實驗37
．登入系統37
．分割私鑰38
．加密私鑰片段39
．分散儲存加密後的私鑰片段41
4.1.2以八台電腦進行儲存之實驗42
．分散儲存加密後的私鑰片段42
4.2還原之實驗結果45
4.2.1以四台電腦進行還原之實驗45
．身分驗證45
．伺服器取回私鑰片段46
．解密被加密之私鑰片段46
．重組解密後的私鑰48
4.2.2以八台電腦進行還原之實驗48
．伺服器取回私鑰片段48
．解密被加密之私鑰片段49
．安全性討論50
．混淆訊息對提升安全性之幫助50
．分散式儲存對提升安全性之影響51
第五章 結論與未來工作53
參考文獻55

圖目錄
圖2.1 MerkleTree Hash示意圖7
圖2.2 新區塊產生流程圖8
圖2.3 數位簽章運作示意圖11
圖2.4 區塊鏈中交易驗證示意圖12
圖2.5 智能合約部署與EVM互動圖14
圖2.6 DApp與SmartContract關係說明17
圖2.7 Chainalysis分析比特幣遺失詳細數據18
圖2.8 Chainalysis分析比特幣遺失比例圖19
圖2.9 DEX交易量24
圖3.1 分散式儲存私鑰流程圖30
圖3.2 私鑰片段加密示意圖32
圖3.3 分散式還原私鑰流程圖34
圖3.4 加密私鑰片段還原35
圖3.5 使用者私鑰重組示意圖36

表目錄
表2.1 近年交易所被駭清單22
表4.1 含識別訊息之私鑰片段加密運算過程40
表4.2 同群組電腦儲存內容明細41
表4.3 同一型態私鑰區段分送至不同電腦儲存紀錄表42
表4.4 第一群組電腦儲存明細表43
表4.5 第二群組電腦儲存明細表43
表4.6 加密私鑰片段解密運算過程47

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