無線感測網絡 (Wireless Sensor Network; WNS) 主要功能是通過部署的感測器節點我們可以收集和傳輸各種資料，並送回後端資料庫。例如，可應用於智能(城市、計量、農業、環境、畜牧業）、零售、監控、電子醫療、軍事應用等。
在WSN中，確保資料傳輸的安全性是至關重要的。我們通常使用安全加密技術來實現，因此需要分享密鑰。密鑰預分配 (Key Pre-distribution; KP) 是一種最常使用於WSN的密鑰分配技術，用於建立感測器節點之間安全通訊的密鑰以確保收集的資料在傳輸過程中的機密性。藉由使用KP技術WSN能夠更有效地保護資料安全。大多數關於KP相關方案的研究都集中在增強抵禦節點攻擊的韌性，同時保持節點鏈路的連通性。在這些方案中，將密鑰事先分配給感測器節點，使它們能夠進行安全通訊。然而，傳統的KP方案在大規模WSN中可能會面臨諸多挑戰，例如密鑰管理的複雜性、能源效率和安全性之間的平衡等。本論文主要就是研究這個主題。為了應對大規模WSN的需求，一種常見的方法是採用多個匯集器無線感測網路 (Multiple Sinks WSN; MWSN) 的架構。MWSN通常由多個群組所組成，每個群組都有一個匯集器節點。這種架構可以提供更多的感測器節點，同時具有較好的連接性和節點容錯性。基於新的MWSN環境，在此基礎上提出了組內和組間密鑰預分配(intragroup and intergroup KP: I2KP)機制，使得通過大規模WSN的不同匯集器節點收集資料時實現安全性和能源效率的平衡。我們提出了四種不同類型的I2KP方案: I2KP using different key pool (I2KPDP)、I2KP using same key pool (I2KPSP)、I2KP using hash chain (I2KPHC)、I2KP using bidirectional hash chain (I2KPBH)。
為了評估I2KP的有效性，我們進行了理論分析和數值模擬。結果表明，所提出的I2KP方法可以有效地提高大規模WSN的安全性和能源效率。這四種I2KP都滿足組內和組間的密鑰分配條件、各有其利弊。根據攻擊者已知的信息量，本論文也討論了三種攻擊形式：節點攔截攻擊(Node Capture Attack; NA)、位置節點攔截攻擊 (Location NA; LNA)、和加強型節點攔截攻擊 (Advanced NA ; ANA)。根據對NA、LNA、ANA的抵抗性、建立鏈路所需的雜湊運算、及感測器節點的儲存密鑰數，我們可以選取適用的I2KP。

The major task of wireless sensor network (WSN) is data collection. Via the deployed sensor nodes we may collect data and send back to backend database for applications. For example, it can be applied on smart (cities, metering, agriculture, environment, animal farming), retail, surveillance, e-Health, military applications.
In WSN, it is very important to ensure the security of data transmission. We usually achieve confidentiality by using encryption, on which a key distribution is required. KP (Key pre-distribution; KP) is often adopted in WSN for key distribution to establish secure links between neighbor sensor nodes. Most researches on KP-like schemes are dedicated on enhancing resiliency against node capture attack, and meantime retain the link connectivity. However, traditional KP schemes are not suitable for large-scale WSNs, such as the complexity of key management, the balance between energy efficiency and security. This thesis deals with the topic about using KP in large-scale WSNs. Toward a large scale WSN, a popular way is to adopt the multiple sinks WSN (MWSN) approach to provide a large number of sensor nodes. In MWSN, there are different clusters (referred to as groups). Based on the new MWSN environment, we present intragroup and intergroup KP (I2KP) to fulfil both requirements of security and energy efficiency when gathering data via various sink nodes in large scale WSN. In this thesis, we propose four types of I2KP: : I2KP using same key pool (I2KPSP)、I2KP using different key pool (I2KPSP)、I2KP using hash chain (I2KPHC)、I2KP using bidirectional hash chain (I2KPBH).
To evaluate the effectiveness of I2KP, we perform theoretical analyses and numerical simulations. Experimental results demonstrate that the proposed I2KP scheme can effectively achieve security and meantime improve energy efficiency of large-scale WSNs. All these four schemes satisfying intragroup and intergroup conditions can be applied to MWSN environment, and have their pros and cons. There are three attacks based on the amount of information known to the attacker: node capture attack (NA), location NA (LNA), and advanced NA (ANA). According to the resiliencies against NA, LAN and ANA, the required hash operations of establishing a secure link, and the key ring sizes of sensor nodes, we may choose one of these four types I2KP for MWSN.

Chapter 1 Introduction 1
1.1 Background 1
1.2 The Organization of The Thesis 2
Chapter 2 Previous Works 5
2.1 Hash Chain 5
2.2 KPHC 6
Chapter 3 Motivation 7
Chapter 4 The Proposed I2KP 11
4.1 The Proposed I2KPDP 11
4.2 The Proposed I2KPSP 22
4.3 The Proposed I2KPHC 29
4.4 The Proposed I2KPBH 47
Chapter 5 Comparison and Numerical Simulations 55
5.1 Comparison 55
5.2 Numerical Simulation 58
5.2.1 Resiliency 58
5.2.2 Computation Overhead 66
Chapter 6 Conclusion and Future Work 69
References 70

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