Network Coding and Wireless Physical-layer ... - Jacobs University

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Chapter 7 Physical-layer Key Encoding for Wireless Physical-layer Secret-key Generation (WPSG) with Unequal Security Protection (USP) The previous chapter concerns mainly the process of secret key generation. It does not tell how the encryptor uses the key. In this chapter, we discuss the one-time-pad encryptor as well as a technique called “physical-layer key encoding” used to enhance security when that kind of encryptor is used. An information-theoretic analysis of physical-layer key generation given in the previous chapter states that there are vulnerable key symbols that might be estimated by eavesdroppers. To protect those key symbols, we introduce physical-layer key encoding in Section 7.1. After that, in Section 7.2, we provide necessary and sufficient conditions on the code in order to achieve perfect secrecy as a function of the number of vulnerable bits and derive the asymptotic code rate accordingly. This perfect secrecy is guaranteed even when the eavesdropper knows the code. When the number of vulnerable symbols is unknown but the ratio between the number of vulnerable key symbols and the total number of generated key symbols is given instead, we suggest an equivalent design parameter 91
92 Chapter 7: Physical-layer Key Encoding for Wireless Physical-layer Secret-key Generation (WPSG) with Unequal Security Protection (USP) used to achieve perfect secrecy in Section 7.3. However, perfect secrecy for the key encoding scheme may require key input that is too long to be economical, especially if the number of vulnerable key bits is large. In the case of scalable data, such as video data, perfect secrecy is not required for the whole data. Even though low-priority parts in the data do not have perfect secrecy, the enemy cryptanalyst will have no idea at all about the data if high-priority parts are properly protected. From now on, we will call this concept “scalable security” or “unequal security protection (USP).” Previous research on scalable security is discussed in Section 7.4. After that, we propose a new framework in Section 7.5 to provide scalable security services to the application layer. This framework allows the application layer to specify some design parameters according to its scalable security requirements, which, as shown in Sections 7.6 and 7.7, can be realized in the contexts of secure network coding and physical-layer key encoding, respectively. In the end, Section 7.8 concludes the chapter and suggests some future research. 7.1 Introduction to Physical-layer Key Encoding for a One-Time-Pad Encryptor As demonstrated in Sections 6.2 and 6.5 of Chapter 6, vulnerable key symbols that can be estimated by an eavesdropper exist in high proportion if there are too few scatterers in the environment, the eavesdropper is located near either the transmitter or the receiver, or, in the case of relay communication, the pilot transmission protocol is insecure. Moreover, although the eavesdropper is nowhere near the transmitter or receiver during transmission, he or she may have been there before and it is possible that channel coefficients (especially the amplitudes) do not change much. Therefore, assuming that he or she can correctly predict some key symbols, we should try to find some countermeasures. To do so, we adopt a similar concept to Shamir’s secret sharing [9] and Cai and Yeung’s secure network
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Network Coding and Wireless Physica
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Abstract The general abstraction of
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Contents Abstract i Abstract ii Dec
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vi CONTENTS 5.4 Degree Distribution
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List of Figures 2.1 A basic digital
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x LIST OF FIGURES 5.11 Comparison o
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Part I Motivation, Overview, and In
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Chapter 1: Motivation and Overview
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Chapter 2 Introduction to Digital C
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Chapter 2: Introduction to Digital
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33 The emergence of scalable video
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Chapter 4: Unequal Erasure Protecti
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Page 132 and 133: Bibliography [1] 3GPP, “3GPP; Tec
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Page 138 and 139: BIBLIOGRAPHY 125 [63] S. Jaggi, P.
Page 140: BIBLIOGRAPHY 127 [81] X. Sun, X. Wu
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Network Coding and Wireless Physical-layer ... - Jacobs University

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