Power-Efficient Schemes for Key Management and Data Aggregation in Wireless Sensor Networks

隨著資訊科技的發展，生活上的科技產品越來越精細，而這些精細的產品有一共通特性：細、薄、輕、結構簡單、成本低。要達成這些特性，其構成元件必須『精簡』；所以在構成元件之電源提供、記憶體、運算能力、通訊能力等都受到嚴重的限制。而這些產品可以透過無線通訊建立無線網路。當這無線網路是由一些結構簡單、成本便宜的感知元件構成，則稱之為無線感知網路。 過去20多年來，因為這些嚴格的限制，使得我們一般所用的公開金鑰協定這類的演算法都不適用於感知網路，其原因為計算量大，不適用於計算能力小的裝置，就算勉強套用公開金鑰，其能源消耗、記憶體消耗都是大問題。然而，無線感知網路因為佈置在外，所以能源為一重要考量因素。沒有能源，一切免談。一個安全的無線感知網路，若是沒有好的金鑰管理機制，那收集的資料將被惡意的攻擊者進行竄改；且若是沒有一個好的省能機制，則當能源耗盡，整個網路將無法運轉。所以本文專注在如何在無線感知網路上節省能源。 本論文針對無線感知網路安全議題之研究主要有兩個方向：省能之金鑰管理與省能之資料加總。首先，針對感知網路佈置後，如何在省能下進行金鑰更新；其次針對感知網路之收集資料，進行密文加總。 在金鑰管理方面，我們提出一個利用區塊金鑰組合函數的觀念。利用此組合函數可以產生出n!個金鑰。而此金鑰函數在產生金鑰時，其過程消耗之能源是可預期的。進而進行能源控管。而此函數提出後，我們接著利用基因演算法進行最佳化，找出在某些特定條件下符合能源消耗的金鑰組合函數。此金鑰組合函數可以達到任兩點皆可建立連線、記憶體消耗小、能源消耗少等特性。 在感應資料加總方面，我們提出一個利用秘密分享結合隱藏資料加總機制，來降低傳送資料量達到省能目的。在實際應用下感知器因為成本便宜，故故障率高。當感知器故障數目增加時，其他機制不是需耗費大量能源傳送故障感知器之辯證碼就是金鑰管理並不安全；而我們的方法則可以不受此影響，傳送之資料量固定且利用秘密分享之方式使得攻擊者需要至少攻陷c個點才能得知該區域內之金鑰。Over the last two decades, we have seen growing importance placed on research in wireless sensor networks (WSNs). A WSN is composed of hundreds of thousands tiny devices, some headers, and some sink nodes. The headers and forward nodes are more powerful than sensor nodes. A sink node is usually a server and is located at a safe location. Generally, there are four main constraints of a sensor node, namely battery energy, computation capability, memory size, and communication protocols. Many literatures investigate security issues including: key management, location deployment, concealed data aggregation (CDA), routing paths and so on. However, the issue of saving power is aimed in this dissertation. To deal with this problem, two rekeying schemes and a concealed data aggregation scheme under power-saving are proposed. This dissertation is composed of two parts, one is rekeying schemes based on code slices, and another is concealed data aggregation scheme based on secret sharing. In the first part, two reliable and efficient rekeying schemes for wireless sensor networks are proposed. One is an efficient rekeying scheme based on code slices, and another is an efficient key management scheme based on genetic algorithms. The sensor system is divided into sinks, headers and sensor nodes. The sink nodes find out a lower power consumption rekeying function and broadcast it randomly. The headers and sensor nodes will collaborate and assemble the code slices to finish the rekeying. Experiments show that the proposed schemes can find the lower power consumption rekeying functions and consume the energy smoothly. In end-to-end encryption, how to maintain security has become a challenging research issue. To save the overall energy resources and maintain the security, computation cost needs to reduce as well as the amount of encrypted data transmitting through the wireless sensor networks. One plausible approach is to consolidate the encrypted data along the routing path. In the second part, a novel concealed data aggregation scheme is proposed to save power by reducing the delivering package sizes. It is provably secure up to some fixed number of compromised nodes.CONTENTS III LIST OF TABLES V LIST OF FIGURES VI 中文摘要 VII 中文摘要 VII ABSTRACT VIII ACKNOWLEDGEMENTS IX 1. INTRODUCTION 1 1.1 SECURITY ISSUES IN WIRELESS SENSOR NETWORKS 1 1.1.1 KEY MANAGEMENT 2 1.1.2 DATA CONFIDENTIALITY 3 1.2 SIGNIFICANCE OF THE RESEARCH 4 1.3 CONTRIBUTIONS 5 1.4 OUTLINE OF THE DISSERTATION 6 2. NETWORK MODEL FOR WIRELESS SENSOR NETWORKS 7 2.1 NETWORK MODEL FOR REKEYING SCHEME 9 2.2 NETWORK MODEL FOR CONCEALED DATA AGGREGATION SCHEME 11 3. REVIEW OF RELATED WORKS 13 3.1 REVIEW OF RELATED REKEYING WORKS 13 3.2 REVIEW OF RELATED CONCEALMENT DATA WORKS 19 4. THE PROPOSED REKEYING SCHEMES 24 4.1 AN EFFICIENT REKEYING SCHEME BASED ON CODE SLICES FOR WIRELESS SENSOR NETWORKS 24 4.2 A GA-BASED KEY-MANAGEMENT SCHEME IN HIERARCHICAL WIRELESS SENSOR NETWORKS 35 5. AN EFFICIENT CONCEALED DATA AGGREGATION SCHEME BASED ON SECRET SHARING 53 5.1 A NOVEL CONCEALED DATA AGGREGATION SCHEME BASED ON SECRET SHARING 53 5.3 CONCEALED DATA AGGREGATION BASED ON SECRET SHARING 57 5.4 PROOF OF CORRECTNESS 61 5.5 SECURITY ANALYSIS AND DISCUSSION 62 5.6. REMARKS 70 6. CONCLUSIONS AND FUTURE WORKS 71 BIBLIOGRAPHY 72 PUBLICATION LIST 78 VITA 8