结合全双工与协作干扰的无线网状网物理层安全策略

针对无线网状网中缺少窃听者先验知识不利场景中的安全连接问题,提出了一种结合全双工和协作干扰技术的物理层安全策略。利用全双工通信中的自干扰消除技术和协作干扰技术,提出的安全策略可有效劣化位于信息传播范围内包括潜伏在接收节点附近窃听者的接收性能。为保证信息的安全传输给出了协作干扰节点的选择方法,基于随机几何等数学方法导出了选定路径的安全连接概率表达式。性能分析和仿真结果表明,所提方法与仅基于全双工或协作干扰技术的方法相比,其安全性能有较大提升。     

贝塔混合模型的变分贝叶斯学习及应用

贝塔混合模型（Beta Mixture Model,BMM）是一种重要的非高斯概率模型,常用于有界数据的统计分析.但是由于其表达式复杂,BMM的参数估计比较困难.针对该问题,本文提出一种高效的变分贝叶斯学习方法进行参数估计.该方法采用形式简单的自由分布,通过不断最大化初始变分目标函数的下界,迭代逼近得到真实的贝叶斯后验分布.在合成数据集与实际数据集上进行实验,实验结果证明了所提出算法的有效性和可行性.     

Secure sensors data acquisition and communication protection in eHealthcare: Review on the state of the art

Recent advances in hardware technology have led to the development of low cost, power efficient and more feature rich devices that are amongst the most critical parts of communication networks. These devices or sensors can now sense data with more accuracy, process it by themselves and send it to the neighboring node or the sink node. However, robust and reliable security mechanisms are not yet properly implemented on these sensors due to their limited energy and computation power. Sensors also play a very important role in eHealthcare systems where ubiquitous patient monitoring is performed. As data is generated from the sensor nodes, reliable, secure and attack-resistant data acquisition and transmission is important for an efficient eHealthcare systems. This survey focuses on security issues of sensors data acquisition and transmission protocols, describing their main security features and comparing them in the context of a secure eHealthcare system. A taxonomy of open issues and future challenges is also discussed with respect to specific security metrics described in the paper.     

Research on color QR code watermarking technology based on chaos theory

In order to carry on copyright protection and security verification of color QR code,the digital image chaos encryption technology and digital watermarking technology were respectively researched.Firstly,an improved image chaos encryption algorithm was proposed as a preprocessing step of digital watermarking algorithm.Then a color QR code digital watermarking algorithm was designed based on discrete wavelet transform and matrix singular value decomposition.Finally,the feasibility of the algorithm was verified by experiments.The results show that the proposed method has good resistance to JPEG compression,noise attack and cropping attack.     

Android collusion attack detection model

In order to solve the problem of poor efficiency and low accuracy of Android collusion detection,an Android collusion attack model based on component communication was proposed.Firstly,the feature vector set was extracted from the known applications and the feature vector set was generated.Secondly,the security policy rule set was generated through training and classifying the privilege feature set.Then,the component communication finite state machine according to the component and communication mode feature vector set was generated,and security policy rule set was optimized.Finally,a new state machine was generated by extracting the unknown application’s feature vector set,and the optimized security policy rule set was matched to detect privilege collusion attacks.The experimental results show that the proposed model has better detective efficiency and higher accuracy.     

Cooperative secret key generation for multi-hop relaying systems in Internet of things

The achievable key rate of secret key generation method in multi-hop relaying systems was relative low in Internet of things.A cooperative secret key generation algorithm based on network coding was proposed to improve the achievable key rate.Firstly,all the nodes send training sequences in turn to estimate the channels.After that the relays employ secure network coding technique to assist the two legitimate users to obtain the correlative observations of the same wireless channel,with nothing leakage about the channel information to the eavesdropper.Finally,the two legitimate users agreed on a common secret key directly over the public channel.Theoretical and simulation results validate the performance of the proposed secret key generation algorithm,and obtain that increasing the wireless transmission paths,selecting the transmission path with less hops and larger variance channels can further improve the achievable secret key rate.     

无线协作网络中的最优中继选择方案及中断概率分析

从物理层安全的角度出发,在含有协作中继的通信网络中,通过选择最优中继来传递信息可有效提升系统性能。讨论了在含有多个单天线窃听用户的多中继通信系统中对最优中继的选择方案,并对系统采用放大转发（amplify-and-forward,AF）协议和解码转发（decode-and-forward,DF）协议这两种不同的情况分别进行了讨论和比较,同时还对比了不含中继的直接传输情况。理论分析和仿真结果表明,最优中继选择方案可有效保障系统的安全性能。     

Metric and classification model for privacy data based on Shannon information entropy and BP neural network

Aiming at the requirements of privacy metric and classification for the difficulty of private data identification in current network environment, a privacy data metric and classification model based on Shannon information entropy and BP neural network was proposed. The model establishes two layers of privacy metrics from three dimensions. Based on the dataset itself, Shannon information entropy was used to weight the secondary privacy elements, and the privacy of each record in the dataset under the first-level privacy metrics was calculated. The trained BP neural network was used to output the classification result of privacy data without pre-determining the metric weight. Experiments show that the model can measure and classify private data with low false rate and small misjudged deviation.     

基于Markov演化博弈的网络防御策略选取方法

当前运用博弈理论的网络安全研究大多采用完全理性假设,本文针对现实社会中攻防双方的有限理性限制条件和攻防过程的动态变化特征,基于非合作演化博弈理论,从有限理性约束出发,将演化博弈模型与Markov决策相结合,构建多阶段Markov攻防演化博弈模型,实现对多阶段、多状态攻防对抗的动态分析推演;依据博弈的折扣总收益设计目标函数,提出多阶段博弈均衡的求解方法,给出最优防御策略选取算法.通过实验验证了模型和方法的有效性.     

基于NTRU的全同态加密方案

本文提出一种基于公钥密码体制（Number Theory Research Unit,NTRU）选择明文攻击（Chosen Plaintext Attack,CPA）可证明安全的全同态加密方案.首先,对NTRU的密钥生成算法进行改进,通过格上的高斯抽象算法生成密钥对,避免了有效的格攻击,同时,没有改变密钥的分布.然后,基于改进的NTRU加密算法,利用Flattening技术,构造了一个全同态加密体制,并在标准模型下证明方案是选择明文攻击不可区分性IND-CPA安全的.