Encrypted Finite-Horizon Energy-to-Peak State Estimation for Time-Varying Systems Under Eavesdropping Attacks: Tackling Secrecy Capacity

This paper is concerned with the problem of finitehorizon energy-to-peak state estimation for a class of networked linear time-varying systems.Due to the inherent vulnerability of network-based communication,the measurement signals transmitted over a communication network might be intercepted by potential eavesdroppers.To avoid information leakage,by resorting to an artificial-noise-assisted method,we develop a novel encryption-decryption scheme to ensure that the transmitted signal is composed of the raw measurement and an artificial-noise term.A special evaluation index named secrecy capacity is employed to assess the information security of signal transmissions under the developed encryption-decryption scheme.The purpose of the addressed problem is to design an encryptiondecryption scheme and a state estimator such that:1)the desired secrecy capacity is ensured;and 2)the required finite-horizon–l_(2)-l_(∞)performance is achieved.Sufficient conditions are established on the existence of the encryption-decryption mechanism and the finite-horizon state estimator.Finally,simulation results are proposed to show the effectiveness of our proposed encryption-decryption-based state estimation scheme.

Eavesdropping Area for Evaluating the Security of Wireless Communications

Compared with wired communication,the wireless communication link is more vulnerable to be attacked or eavesdropped because of its broadcast nature.To prevent eavesdropping,many researches on transmission techniques or cryptographic methods are carried out.This paper proposes a new index parameter named as eavesdropping area,to evaluate the anti-eavesdropping performance of wireless system.Given the locations of legitimate transmitter and receiver,eavesdropping area index describes the total area of eavesdropping regions where messages can be wiretapped in the whole evaluating region.This paper gives detailed explanations about its concept and deduces mathematical formulas about performance curves based on region classification.Corresponding key system parameters are analyzed,including the characteristics of eavesdropping region,transmitted beam pattern,beam direction,receiver sensitivity,eavesdropping sensitivity,path loss exponent and so on.The proposed index can give an insight on the confirmation of high-risk eavesdropping region and formulating optimal transmitting scheme for the confidential communications to decrease the eavesdropping probability.

Eavesdropping on the＇ping-pong＇ quantum communication protocol freely in a noise channel

We introduce an attack scheme for eavesdropping freely the ping-pong quantum communication protocol proposed by Bostrǒm and Felbinger [Phys. Rev. Left. 89, 187902 （2002）] in a noise channel. The vicious eavesdropper, Eve, intercepts and measures the travel photon transmitted between the sender and the receiver. Then she replaces the quantum signal with a multi-photon signal in the same state, and measures the returned photons with the measuring basis, with which Eve prepares the fake signal except for one photon. This attack increases neither the quantum channel losses nor the error rate in the sampling instances for eavesdropping check. It works for eavesdropping the secret message transmitted with the ping-pong protocol. Finally, we propose a way for improving the security of the ping-pong protocol.

Joint Trajectory and Power Optimization for Securing UAV Communications Against Active Eavesdropping

Due to both of jamming and eavesdropping,active eavesdroppers can induce more serious security threats to unmanned aerial vehicle(UAV)-enabled communications.This paper considers a secure UAV communication system including both the downlink(DL)and uplink(UL)transmissions,where the confidential information is transmitted between a UAV and a ground node in the presence of an active eavesdropper.We aim to maximize the average secrecy rates of the DL and UL communications,respectively,by jointly optimizing the UAV trajectory and the UAV/ground node’s transmit power control over a given flight period.Due to the non-convexity of the formulated problems,it is difficult to obtain globally optimal solutions.However,we propose efficient iterative algorithms to obtain high-quality suboptimal solutions by applying the block coordinate descent and successive convex optimization methods.Simulation results show that the joint optimization algorithms can effectively improve the secrecy rate performance for both the DL and UL communications,as compared with other baseline schemes.The proposed schemes can be considered as special cases of UAV-assisted non-orthogonal multiple access(NOMA)networks.

Multi-user quantum key distribution with collective eavesdropping detection over collective-noise channels

A multi-user quantum key distribution protocol is proposed with single particles and the collective eavesdropping detection strategy on a star network. By utilizing this protocol, any two users of the network can accomplish quantum key distribution with the help of a serving center. Due to the utilization of the collective eavesdropping detection strategy, the users of the protocol just need to have the ability of performing certain unitary operations. Furthermore, we present three fault-tolerant versions of the proposed protocol, which can combat with the errors over different collective-noise channels.The security of all the proposed protocols is guaranteed by the theorems on quantum operation discrimination.

Game theory-based attack and defense analysis in virtual wireless networks with jammers and eavesdroppers

Dynamic spectrum sharing and cognitive radio networks were proposed to enhance the Radio Frequency(RF)spectrum utilization.However,there are several challenges to realize them in real systems,such as sensing uncertainty causing issues to licensed users,business models for licensed service providers.Wireless virtualization is regarded as a technology that leverages service level agreements to sublease unused or underutilized RF spectrum that addresses aforementioned issues and helps to significantly enhance the utilization of the RF spectrum,offer improved coverage and capacity of networks,enhance network security and reduce energy consumption.With wireless virtualization,wireless networks'physical substrate is shared and reconfigured dynamically between virtual wireless networks through Mobile Virtual Network Operations(MVNOs).Wireless virtualization with dynamic configurable features of Wireless Infrastructure Providers(WIPs),virtualized wireless networks are vulnerable to a multitude of attacks,including jamming attacks and eavesdropping attacks.This paper investigates a means of defense through the employment of coalition game theory when jammers try to degrade the signal quality of legitimate users,and eavesdroppers aim to reduce secrecy rates.Specifically,we consider a virtual wireless network where MVNO users'job is to improve their Signal to Interference plus Noise Ratio(SINR)while the jammers target to collectively enhance their Jammer Received Signal Strength(JRSS),and an eavesdropper's goal is to reduce the overall secrecy rate.Numerical results have demonstrated that the proposed game strategies are effective(in terms of data rate,secrecy rate and latency)against such attackers compared to the traditional approaches.

A two-stage amplifier of laser eavesdropping model based on waveguide fiber taper

In order to improve ability of amplification about optical arrival angle in laser eavesdropping system, and enhance receiving field of view (FOV) of laser eavesdropping system, this paper presents a new multistage amplifier laser eavesdropping model based on waveguide fiber taper. First of all, taking about four-quadrant (4QD) laser eavesdropping model as an example, from the theoretical view, analyses factors that, currently, laser eavesdropping system face many restrictive factors during practical applications. Besides, from the receiving FOV and ability of amplification about arrival angle of incoming optical axis angles, systematically analyses advantages of multi-stage amplifier model. What’s more,through constructing laser eavesdropping test platform, we demonstrate Signal to Noise Ratio(SNR) of two stage amplification model is eventually promoted to 6-10 dB compared with one amplifying model,especially in low and high audio level, the advantages is more obvious.

An Anti-Eavesdropping Method in Data Collection of Smart Meter

At present, DL/T 645-2007 communication protocol is used to collect data for smart meters. However, in the beginning, this protocol is not designed to be a secure protocol and only the function and reliability were taken into account. Plaintext is used in the protocol for data transmission, as a result, attackers can easily sniff the information and cause information leakage. In this paper, man-in-the-middle attack was used to verify that the smart meter data acquisition process was vulnerable when facing third-party attacks, and this can result in data eavesdropping. In order to resist such risks and prevent information being eavesdropped, a real ammeter communication experimental environment was built, it realized two-way identity authentication between data acquisition center and ammeter data center. At the same time, RSA (Rivest-Shamir-Adleman) was used to encrypt the meter data, which encrypted the collection, storage process of meter data and ensured the confidentiality and integrity of the meter data transmission. Compared with other methods, this method had obvious advantages. The analysis showed that this method can effectively prevent the data of smart meters from being eavesdropped.

A physical layer security scheme for full-duplex communication systems with residual self-interference and non-eavesdropping CSI

We discuss the physical layer security scheme in the Full-Duplex(FD)MIMO point-to-point two-way communication system with residual self-interference,in which legitimate nodes send confidential information and null space Artificial Noise(AN)while receiving information.Because the Channel State Information(CSI)of the eavesdropper is unavailable,we optimize the covariance matrices of the information signal as well as the allocation of the antenna for transmitting and receiving to minimize the signal power consumption under the target rate constraint.As a result,the power of AN is maximized within the limit of total power,so the interception capability of the eavesdropper is suppressed as much as possible.Since self-interference cannot be completely eliminated,the optimization process of one legitimate node depends on the optimization result of the other.By substituting self-interference power in the secrecy rate formula with its average value,the joint optimization process at the two nodes is transformed into two separate and solvable optimization processes.Then,the Water-Filling Algorithm(WFA)and bisection algorithm are used to get the optimal covariance matrices of the signal.Furthermore,we derive the theoretical lower bound of ergodic achievable secrecy rate under rayleigh channels to evaluate the performance of the scheme.The simulation results show that the theoretical derivation is correct,and the actual achievable rate is very close to the target rate,which means that the approximation in the optimization is feasible.The results also show that secrecy transmission can be realized because a considerable secrecy rate can be achieved.

A Spectrum Sharing Model that Counters Eavesdropping:An Energy Efficiency View

Wireless transmission is subject to eavesdropping.When wireless transmission ceases,the assigned frequency channel is unused,wasting the spectral opportunity given.In this study,a spectrum sharing model that reduces spectral wastage and protects against eavesdropping is proposed.First,cognitive radio(CR)shares the channel access with primary user(PU).When the CR senses that the channel is idle,CR can seize the unoccupied channel for its own use.If the channel is detected to be occupied by PU,CR transmits artificial noise to jam any potential eavesdropper.To what extent is this operation beneficial to the CR?The main concern of this study is the energy efficiency(μ)of CR,i.e.,the ratio of channel throughput to its energy consumption.The relationship betweenμand the percentage of frame duration allocated for sensing(τ)was investigated.This study contributes a novel theoretical expression that allows us to find the optimalμandτvalues,denoted byμ∗andτ∗.With the availability of this expression,the relationships between(μ∗,τ∗)and other important system parameters can be understood thoroughly.Our investigation reveals that strong CR signal will result in highμ∗without the need of increasingτ∗.On the other hand,a strong primary signal allows a shortτ∗and it improvesμ∗.High sampling rate for sensing may be unnecessary,as it does not improveμ∗significantly.A more demanding target probability of detection requires a higher sensing duration,but it has insignificant impact onμ∗.

A Novel Basis Splitting Eavesdropping Scheme in Quantum Cryptography Based on the BB84 Protocol

We propose a novel strategy numed basis-splitting scheme to split the intercepted quanta into several portions based on different bases, for eavesdropping in the process of quantum cryptography. Compared with intercept- resend strategy, our simulation results of the basis-splitting scheme under the non-ideal condition show a greater performance, especially with the increase of the length of shifted bits. Consequently our scheme can aid eaves- dropper to gather much more useful information.

Eavesdropping on Quantum Secure Direct Communication with W State in Noisy Channel

量的安全安全直接通讯协议(即， C-S QSDC 协议) 最近由 Cao 和歌求婚了[下巴。Phys。Lett。23 (2006 ) 290 ] 在可观的量隧道噪音的情况中被分析。如果量隧道噪音引起的量小点错误率(QBER ) 比 4.17% 高，偷听的计划被介绍，它表明 C-S QSDC 协议不是安全的。我们的偷听的计划为那些检查 qubits 导致大约 4.17% QBER。然而，如此的 QBER 能在如果偷听者伊夫在理想的代替原来的吵闹的隧道，由吵闹的量隧道导致的对应物被隐藏。而且，如果量隧道噪音导致的 QBER 比 4.17% 低，那么仍然在偷听策划伊夫能偷听秘密的部分由安全地攻击发送消息很少的播送 qubits。最后， C-S QSDC 协议上的改进被提出。

An Anti-Eavesdrop Transmission Scheduling Scheme Based on Maximizing Secrecy Outage Probability in Ad Hoc Networks

In this paper,we consider a wireless ad hoc network consisting of multiple source nodes transmitting to their respective destinations,where an eavesdropper attempts to intercept their transmissions.We propose an optimal transmission scheduling scheme to defend against the eavesdropper,where a source node having the highest secrecy rate is scheduled to access the wireless medium for transmitting to its destination in an opportunistic manner.To be specific,the secrecy rate between a pair of the source and destination in the presence of an eavesdropper varies temporally due to the wireless fading effect.The proposed optimal transmission scheduling scheme opportunistically selects a source node with the highest secrecy rate to transmit its data for the sake of maximizing the security of the ad hoc network against eavesdropping attacks.For comparison purposes,we also consider the conventional round-robin scheduling as a benchmark,where multiple source nodes take turns in accessing their shared wireless medium for transmitting to their respective destinations.We derive closed-form secrecy outage probability expressions of both the round-robin scheduling and the proposed optimal scheduling schemes over Rayleigh fading environments.Numerical results show that the proposed transmission scheduling scheme outperforms the conventional round-robin method in terms of its secrecy outage probability.Additionally,upon increasing the number of source-destination pairs,the secrecy outage probability of the round-robin scheme keeps unchanged,whereas the secrecy outage performance of the proposed transmission scheduling significantly improves,showing the security benefits of exploiting transmission scheduling for protecting wireless ad hoc networks against eavesdropping.

Secure resource allocation against colluding eavesdropping in a user-centric cell-free massive multiple-input multiple-output system

We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel estimation.Aiming at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral efficiency.Simulation results show that the proposed scheme can effectively reduce channel estimation error and improve system security.

基于部分信息的SLT-LT联合码防窃听方案设计

近年来,信息的安全传输备受人们关注,现有的物理层安全技术从信息论的角度出发,将物理层安全编码与传输信道的动态物理特性进行结合,实现信息的保密传输。作为一种纠删码,LT(Luby transform)码由于其编码随机性、码率不固定等特性,使得窃听者不能直接从泄露的编码符号中得到有用信息,只要合法用户在窃听者之前接收到足够数量的编码符号,便可实现信息的安全传输。而作为一种转移LT(Shifted LT,SLT)码,SLT码能高效恢复信息的同时具有更小的译码开销。因此,我们将SLT码应用于Wyner降阶窃听信道模型进行研究,提出一种基于部分信息转移的SLT-LT联合码防窃听方案,信源利用接收者已知的部分信息对度分布进行调整,并对信源符号进行SLT-LT码级联编码。由于窃听信道是合法信道的降阶信道,因此外在的窃听者截获到的消息符号是合法接收者的降阶版本,在相同时间内,合法接收者能够收到更多消息符号,随着编解码过程的不断进行,合法接收者的优势不断累积,能够优先完成解码,而度分布的调整以及级联编码方案使得编码符号的平均度进一步增大,窃听者难以完成解码,进一步降低了窃听者译出率;之后,对所提方案的编解码性能以及安全性进行理论分析,并通过实验仿真进行验证,仿真结果表明,与其他防窃听LT方案相比,本文所提方案仅增加少量的译码开销但具有更好的安全性能。

基于时频特征的反监听技术研究与应用

本研究旨在探讨一种基于时频特征设计的反监听技术,重点研究如何通过动态修改时序和频率增强特定频率范围内的人类语音干扰。本文针对现有的语音干扰技术展开研究,并与标准噪声注入方法进行了比较。研究方法包括理论分析和实验验证,通过对实际原型进行测试和验证,评估了基于时频特征提取的干扰信号在干扰语音识别系统方面的有效性。实验结果显示,当信噪比低于0dB时,所提出方法的文本识别错误率超过了60%;而当信噪比为0dB时,本文算法的文本识别错误率平均比当前干扰算法高出20%以上。此外,当干扰系统与录音设备保持相同距离时,本文算法在录音设备上产生的信噪比比当前算法低近2dB,这说明了所提出算法的高能量利用效率。因此,本研究成果对于提高通信安全和保护隐私具有重要意义,特别是在需要高度保密的通信环境中。

基于欺骗中继技术的无人机主动监听优化方法研究

针对非法分子通过无线通信危害国家安全的问题,研究了基于无人机欺骗中继技术的合法监听方案,对地面可疑节点之间的通信链路进行监听。首先,将节点之间的链路视为视距链路,对各个信道进行建模,构建了监听率最大化的问题。其次,为了解决这个复杂的非凸优化问题,采用深度强化学习方法,综合考虑无人机的三维轨迹、放大系数和功率分配比这三方面对监听率的影响,将该问题建模为马尔可夫决策过程,设计了相应的奖励函数。最后,基于双延迟深度确定性策略梯度算法实现联合优化。从数值结果来看,相较于基于深度确定性策略梯度算法的主动监听优化策略,所提出的优化策略收敛速度更快,所得到的监听性能有所提升。

基于干扰辅助下的多监听器COMP联合监听技术

在无线通信领域,COMP联合通信因其能够显著增强信号质量被广泛运用。考虑利用COMP技术提升物理层信息监听性能,文中采取多个合法监听器对多个正交的可疑通信对进行联合监听,并进一步利用无人机对这些可疑通信对实施干扰,旨在联合优化无人机的位置以及干扰功率分配,以最大化多个可疑通信对的最小监听成功概率。文中使用蒙特卡罗法验证了COMP信噪比的累积分布函数(CDF)近似值和精确值,鉴于提出的优化问题高度非凸,采用连续凸近似和块坐标下降算法对无人机的位置和干扰功率分配进行交替优化,以获取局部最优解。仿真结果表明,相较于其他方案,所提出的方案能够显著提升系统最小监听成功概率。

全双工辅助的无人机上行通信抗窃听物理层安全技术研究

针对无人机上行通信链路的窃听攻击,提出一种全双工协同干扰的安全传输策略。方案利用收发双方在数据传输不同阶段的信息差异以及掌握的先验信息特征,向待传输信号注入人工噪声信号,从而使窃听链路形成干扰受限系统。在发射功率、无人机的机动性等约束条件下,建立最大化系统保密速率的联合优化问题,基于交替优化方法和连续凸近似技术将非凸问题转化为两个子问题,并设计了一种迭代优化算法进行求解。仿真结果表明,所提安全传输方案与其他参照方案相比,能够显著提高全双工无人机中继通信系统的保密速率,表现出更好的性能。

Method for determining the best frequency band for eavesdropping the display image of a PC

The display image of the video display unit （VDU） can be reconstructed by receiving and analyzing the unexpected electromagnetic noise emanated from a personal computer system. This fact is one of the information leakage threats in information security. Therefore, in order to choose the best frequency range for receiving the electromagnetic compromising emanations form a PC display effectively and quickly, a method based on the correlation power analysis （CPA） and the common equipments is proposed. Firstly, the frequency spectrum of 10 MHz to 1 GHz is measured about 10 times respectively when the PC is displaying the white-black vertical strips image and black image. The frequency range which contains the display information can be obtained through the CPA. And then, the special image signal is searched around the dot frequency and harmonics. If the special signal disappears when displaying the total black image, it can be judged to be the real special signal. Finally, the best receiving frequency range can be chosen by comprehensive considering the results of CPA and the signal to noise ratio （SNR） of the special image signal. In order to check the validity of the chosen frequency range, eavesdropping experiments are carried out. The results demonstrate that the selected frequency range can retrieve the higher quality image than other frequency bands.