基于信道差异的物理层安全编码技术研究

发布时间：2018-01-24 20:12

本文关键词： 物理层安全编码 Wiretap模型陪集编码喷泉编码极化编码打孔强安全错误扩散　出处：《解放军信息工程大学》2014年博士论文　论文类型：学位论文

【摘要】：物理层安全编码是一种同时保证私密信息可靠和安全传输的信道编码技术。它利用合法信道与窃听信道的固有差异,在物理层从信息层面直接防止私密信息被窃听。但是现阶段的研究仍然存在以下问题有待改善:(1)保证私密信息强安全传输的随机冗余使得码字间实际汉明距离变小,导致强安全编码的抗噪能力较差;(2)当合法信道与窃听信道均为二进制删除信道(Binary Erasure Channel,BEC)时,编码方式的任何变化对合法接收者和窃听者的影响相同,导致缺乏强安全且可靠的编码;(3)在已知信道统计信息时,尽管利用信道极化理论可以得到强安全且可靠的编码,但是私密信息传输效率较低;(4)现有级联安全编码的安全间隙较大,不利于实现私密信息在合法信道和窃听信道的区分传输。针对上述问题,本文依托国家自然科学基金项目“无线通信信道特征等效下的物理层安全性研究”,首先基于互信息理论和典型序列理论,分析了编码可靠性与安全性的关系,然后以将合法信道与窃听信道较小的特征差异转化为合法接收者与窃听者较大的误比特率差异为主线,面向不同场景,重点研究合法信道有噪时的安全编码技术。主要研究成果如下:1.针对合法信道为高斯信道且窃听信道为BEC时,强安全编码抗噪能力差的问题,提出了一种基于部分陪集的强安全编码。该方法利用信道模型的差异,实现私密信息的区分传输。首先,为了保证强安全,文章证明了当且仅当陪集母码的对偶码的最小汉明距离大于信息泄露位数时,利用部分陪集编码能够保证私密信息在BEC窃听信道的强安全传输。然后,为了提高可靠性和有效性,文章通过分析陪集编码的一系列性质将计算陪集间汉明距离的复杂度简化为1次查表运算,再证明了势最大的部分陪集集合一定包含基准陪集,进而根据最大完全子图理论提出了一种基于树形深度优先的搜索算法,得到了一定距离冗余下的最大可用陪集集合,从而提高私密信息在高斯合法信道的抗噪能力。最后,给出了典型陪集母码下所提方法的抗信息泄露和抗噪声能力,以及相应的最大可用陪集集合。理论分析和仿真结果表明,当陪集母码为BCH(15,11)的对偶码时,与传统陪集编码方案相比,该方法在保证私密信息传输的强安全的同时,对合法信道的信道质量要求降低了5dB。2.针对合法信道与窃听信道均为BEC时,无法同时保证强安全且可靠传输的问题,提出了一种基于爆发喷泉码级联陪集预映射的安全编码方法。该方法利用信道删除概率的差异,实现私密信息的区分传输。首先,利用喷泉码的无速率特性,保证私密信息的可靠传输。然后,通过优化度分布构造了具有爆发译码速度的喷泉码,并利用它随机生成和爆发译码的特性,保证对窃听者泄露尽量少的符号。为了进一步保证强安全,文章在喷泉编码前增加陪集冗余,防止窃听者从已泄露的符号中获取私密信息。仿真结果表明,该方法能够自适应合法信道质量,保证信息的可靠传输,同时减少符号泄露量,便于配合陪集编码保证强安全。3.针对极化安全编码信息速率较低的问题,提出了一种面向私密信息位的极化强安全打孔方案。该方法利用信道极化后逻辑信道传输能力的差异,实现私密信息的区分传输。首先,为了保证私密信息的强安全且可靠传输,文章根据信道极化理论提出了一种安全极化母码构造方法。然后,为了提高私密信息传输的有效性,文章通过分析极化编码器的迭代构造结构,利用3个参数表征输出符号与特定输入位的校验关系,并以仅对私密信息输入位的影响程度最小为原则,提出了一种安全极化码打孔方案。仿真结果表明,当合法信道和窃听信道的交叉转移概率分别为0.01和0.15时,在满足强安全与可靠传输的前提下,所提方法的传输效率提高了12.7%。4.针对级联函数错误扩散能力较弱,不利于通过减小安全间隙将信道编码扩展应用到安全编码的问题,提出了一种基于平衡扩散多输出函数的级联安全编码方法。码字的安全间隙越小,越容易利用信噪比差异,实现私密信息的区分传输。为此,文章首先指出了现有关于随机扰乱方法具有最佳错误放大结论的局限性,然后根据布尔函数理论,构造了满足错误扩散准则的多输入多输出函数,对信道译码后低信噪比区域内的误比特率进行错误放大,达到减小安全间隙的目的。同时,为了防止输入均匀分布时输出出现集中分布,文章进一步优化保证了函数的平衡性。仿真结果表明,与现有方法相比,本文所提方法的错误扩散能力更逼近理论限,安全间隙缩小了3.5dB。
[Abstract]:The physical layer security encoding is a guarantee of channel encoding technology reliable and secure transmission of private information at the same time. It exploits the inherent differences in the legitimate channel and Wiretap Channel, in the physical layer from the aspect of information directly to prevent private information eavesdropping. But the current study is still the following problems need to be improved: (1) random redundancy strong private information secure transmission makes the smaller Hamming distance between the codewords actually lead to strong security guarantee, encoding anti noise ability is poor; (2) when the legitimate channel and wiretap channel are binary erasure channel (Binary Erasure, Channel, BEC), any change of encoding effect on the legitimate receiver and the eavesdropper, leading to a lack of strong safe and reliable encoding; (3) in the known channel statistics, although the use of channel polarization theory can get strong safety and reliable encoding, but private information transmission efficiency Low; (4) the existing security clearance cascade encoding is large, is not conducive to the realization of private information in the transmission channel and distinguish legal Wiretap Channel. Aiming at the above problems, this paper relies on the National Natural Science Fund Project "the physical layer of wireless communication channel characteristics under equivalent safety study, based on the mutual information theory and typical sequence theory analysis of the relationship between encoding, reliability and safety, and to differences in the characteristics of the legitimate channel and small Wiretap Channel into legitimate receiver and the eavesdropper bit error rate larger difference as the main line, for different scenarios, focusing on the legitimate channel safety encoding technology noise. The main research results are as follows: 1. for the legal a channel for the Gauss channel and the wiretap channel is BEC, strong safety encoding poor anti noise ability, a strong safety Part Based on the coset encoding method using. The difference of channel model, realize the transmission of private information. First of all, in order to ensure strong security, this article proves that when and only when the mother sub code the minimum Hamming distance is greater than the number of information disclosure, the part can ensure the safe transmission of coset encoding strong private information in the BEC Wiretap Channel. Then, in order to improve the reliability of and the validity, through the analysis of the computational complexity of the Hamming distance between cosets is simplified into 1 look-up operations and a series of properties of coset encoding, and then prove the potential part of the largest collection of coset must contain reference coset, then according to the maximum complete subgraph theory proposed a tree search algorithm based on depth first, get the maximum available coset of a certain distance from the redundancy set, so as to improve the private information on the legitimate channel Gauss anti noise ability. Finally, gives the typical mother code under the proposed coset The method of anti information leakage and anti noise ability, and the corresponding maximum available coset set. Theoretical analysis and simulation results show that when the mother code is BCH (15,11) dual code, compared with the traditional coset encoding scheme, the method to ensure the safety of the strong private information transmission at the same time, the channel quality of the legitimate channel the requirements for the legitimate channel and reduces the 5dB.2. Wiretap Channel was BEC, at the same time to ensure the strong safety and reliable transmission, proposes a secure encoding method outbreak of fountain codes based on cascaded coset pre mapping. This method uses erasure probability differences, distinguish between the transmission of private information. First of all, no use the rate characteristics of the fountain codes, ensure the reliable transmission of private information. Then, through the optimization of degree distribution is constructed with the outbreak of the decoding speed of fountain codes, and the random generation and decoding the outbreak The characteristics, to ensure the eavesdropper leak less symbols. In order to guarantee the strong safety, increase the redundancy in the fountain before the coset encoding, prevent an eavesdropper access to private information from the leaked symbols. The simulation results show that this method can adaptively legitimate channel quality, ensure the reliable transmission of information, while reducing the amount of leakage of symbols. To ensure the strong security of.3. with coset encoding for the polarization information security encoding rate is low, we propose a new private information a strong polarization safety puncturing scheme. The method uses the difference of channel polarization after logical channel transmission capacity, realize transmission of private information. First of all, in order to ensure the private information safe and strong reliable transmission, the method to construct a safe mother codes according to the channel polarization polarization theory. Then, in order to improve the efficiency of private information transmission, the Through iterative structure analysis of polarization encoder, using 3 parameters characterizing the output symbols with a particular input bit parity relations, and only on the influence of private information input bit principle, proposes a secure polarization code puncturing scheme. The simulation results show that when the cross transfer probability of the legitimate channel and the Wiretap Channel were 0.01 and 0.15, in order to meet the strong security and reliable transmission, the transmission efficiency of the proposed method improves the 12.7%.4. function for the concatenated error diffusion ability is weak, is not conducive to the channel encoding is applied to safety problems by reducing the encoding of security clearance, proposes a security encoding method multi equilibrium diffusion cascade based on the output function. The safety clearance code is smaller, more easily by the signal-to-noise ratio difference, realize the transmission of private information. Therefore, this article firstly points out about now Random perturbation method with the limitations of the optimal error amplification results, then according to the theory of Boolean function, constructed for the multiple input multiple output error propagation criterion function for decoding the low SNR and bit error rates within the area of the error amplifier, to reduce the security gap. At the same time, in order to focus on the distribution of output to prevent the input of uniform distribution, the paper further optimized to ensure balanced function. The simulation results show that compared with the existing methods, the error diffusion ability of the proposed method in this paper is more close to the theoretical limitation of security gap narrowed 3.5dB.

【学位授予单位】：解放军信息工程大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN911.22

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