工作量證明的區塊鏈在安全性上已經在許多研究中被仔細分析，其規模化的能力限制也於社群及文獻中有所探討和延伸。然而，關於使用噴泉碼來控制/加速區塊傳輸的相關主題並未被廣泛討論，因此本研究旨在透過噴泉碼 (或 rateless codes) 來改善區塊鏈系統的網路傳輸能力，進而分析改善後之網路環境對於系統安全性及效能的影響。噴泉碼是一種可以適應於各種erasure rate環境的erasure codes，而LT碼是第一種可實際運用的噴泉碼，其擁有噴泉碼可無限編碼的特性，且編/解碼所需之運算皆為低複雜度。區塊鏈系統為一建構在網際網路上的點對點 (peer-to-peer, P2P) 網路架構，沒有階層、中央處理，本質上相當具有彈性、開放，節點可隨意加入，網路拓樸為隨機生成[18]。然而也因此特性，導致區塊鏈P2P網路的傳輸速度大受影響。在這篇研究中，我們建立一個區塊的傳輸模型，利用
基於模擬的LT碼傳輸控制方法來提高傳輸的效能，並以該傳輸環境來分析區塊鏈系統的安全性以及規模化的能力和限制。實驗的結果顯示系統在以本篇設計的LT碼傳輸環境下擁有較佳的網路吞吐量、較少的冗餘度，並且帶來了更好的安全性以及規模化能力。

The security provisions of the Proof of Work (PoW) blockchain system has been thoroughly analyzed in many researches, and the discussion and extension of the scalability limits of the system have also been found in some communities and literature. However, the research topic employing fountain codes to control/facilitate the transmission of blocks are not well discussed. Therefore, in this paper, the fountain codes (or rateless) are leveraged to improve the transmission ability of the blockchain system, and the impact on the security provisions and the performance of the system over the improved network environment are further analyzed. Fountain codes are a family of erasure codes where the rate can be adjusted on the fly. LT codes are the first realization of the fountain codes with the beneficial properties from it and having low computational complexity in both encoding/decoding as well. Blockchain system is structured as a peer-to-peer network architecture on top of the internet; the P2P means that there are no “special” nodes, no centralized service, and no hierarchy within the network. P2P networks are inherently resilient, open, and the computers are free to participate in the network which has its topology randomly constructed [18]. Due to the mentioned properties of the P2P network, the blockchain system encounters some transmission bottlenecks. We designed a block propagation model with the simulated-based LT codes transmission control mechanism which facilitates the transmission performance to analyze the security provisions and the limits of the scalability of the blockchain system. The results suggest that our proposed method performs a better network throughput, security provisions, scalability, and less redundancy.

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