隨著諸如比特幣（Bitcoin）、以太坊（Ethereum）等系統的流行，越來越多的人聽過加密貨幣這個詞彙。這些系統所擁有的分散式的特性以及其所依賴的各種如：區塊鏈、工作量證明、權益證明等等的技術，使這些系統被大家認為是具有隱私且安全的。但上述的各種技術實際上皆有各自的缺點無法被克服，這使得依賴這些技術的加密貨幣系統必須要在許多利弊，如：中心化、交易吞吐量、系統複雜度、節能以及安全性等，之間進行抉擇。不同的系統依據其面向的使用場景會有不同的選擇，但截至目前為止並沒有一個方案可以滿足日常交易需求，亦即同時滿足完全的去中心化、高的交易吞吐量、可接受的系統複雜度、節能並且足夠安全。
在本篇中，我們基於一種現有的分散式雜湊表傳輸協定，提出了一種完全去中心化並具有自我管理機制的加密貨幣系統。這個系統採用了與現有的加密貨幣系統完全不同的架構，使得我們提出的系統可以克服現有技術的阻礙，並且可以滿足日常交易的需求。我們透過數學分析以及實驗的方式證明了我們提出的系統除了可以用直觀的設計達到極高的交易吞吐量之外，其所採用的類似於權益證明的機制保證了系統節能的特性以及超乎預期的安全性。

As the growth of popularity of the systems like Bitcoin and Ethereum, more and more people have heard about cryptocurrency. The decentralized nature and the supporting techniques, such as Blockchain, Proof of Work (PoW), Proof of Stake (PoS), etc, of the systems makes them be considered private and secure. But those techniques have their own shortcomings which make the cryptocurrency systems built upon them have to make a trade-off between multiple features such as becoming centralized, transaction consumption throughput, system complexity, eco-friendly, security, etc. Different cryptocurrency system has its own choice, but there is not an existing design that is suitable for daily usage which requires fully decentralized, high transaction consumption throughput, simple system architecture, eco-friendly and secure.
In this thesis, we propose a fully decentralized and self-managed cryptocurrency system which is built upon an existing Distributed Hash Table (DHT) protocol that can fulfill all of the requirements for daily usage. The proposed system has totally different architecture compares to existing implementations, which makes it overcome the difficulties and hence no trade-off has to be made. Our analysis and experiments show that the system supports an astonishing high transaction consumption throughput with a straightforward system design. The designed PoS-like consensus algorithm of the system makes it eco-friendly while provides remarkable security.

[1] S. Nakamoto, “Bitcoin: A peer-to-peer electronic cash system,” white paper, Bitcoin.org, 2008.
[2] S. King and S. Nadal, “Ppcoin: Peer-to-peer crypto-currency with proof-of-stake,”self-published paper, August, vol. 19, no. 1, 2012.
[3] W. Li, S. Andreina, J.-M. Bohli, and G. Karame, “Securing proof-of-stake blockchain protocols,” in Data Privacy Management, Cryptocurrencies and Blockchain Technology: ESORICS 2017 International Workshops, DPM 2017 and CBT 2017, Oslo, Norway, September 14-15, 2017, Proceedings, pp. 297–315, Springer, 2017.
[4] I. Visa, “Visa fact sheet,” Onling. Available: https://usa.visa.com/dam/VCOM/global/about-visa/documents/aboutvisafactsheet.pdf, 2023.
[5] S. K ̈ufeo ̆glu and M. ̈Ozkuran, “Bitcoin mining: A global review of energy and power demand,”Energy Research & Social Science, vol. 58, p. 101273, 2019.
[6] V. Buterin et al., “Ethereum: A next-generation smart contract and decentralized application platform,” white paper, vol. 3, no. 37, pp. 2–1, 2014.
[7] P. Maymounkov and D. Mazieres, “Kademlia: A peer-to-peer information system based on the xor metric,” in International Workshop on Peer-to-Peer Systems, pp. 53–65, Springer, 2002.
[8] I. Baumgart and S. Mies, “S/kademlia: A practicable approach towards secure key-based routing,” in 2007 International conference on parallel and distributed systems, pp. 1–8, IEEE, 2007.
[9] F. Saleh, “Blockchain without waste: Proof-of-stake,” The Review of financial studies, vol. 34, no. 3, pp. 1156–1190, 2021.
[10] Bitnodes,“Bitnodes estimates the relative size of the bitcoin peer-to-peer network by finding all of its reachable nodes,” 2013. Accessed: (13/04/2024).
[11] WonderNetwork, “Global ping statistics.” Accessed: (14/04/2024).