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Wuxia Jin, Ting Liu, Yu Qu, Jianlei Chi, Di Cui, Qinghua Zheng.  2016.  Dynamic cohesion measurement for distributed system.

Instead of developing single-server software system for the powerful computers, the software is turning from large single-server to multi-server system such as distributed system. This change introduces a new challenge for the software quality measurement, since the current software analysis methods for single-server software could not observe and assess the correlation among the components on different nodes. In this paper, a new dynamic cohesion approach is proposed for distributed system. We extend Calling Network model for distributed system by differentiating methods of components deployed on different nodes. Two new cohesion metrics are proposed to describe the correlation at component level, by extending the cohesion metric of single-server software system. The experiments, conducted on a distributed systems-Netflix RSS Reader, present how to trace the various system functions accomplished on three nodes, how to abstract dynamic behaviors using our model among different nodes and how to evaluate the software cohesion on distributed system.

Wurzenberger, Markus, Skopik, Florian, Fiedler, Roman, Kastner, Wolfgang.  2016.  Discovering Insider Threats from Log Data with High-Performance Bioinformatics Tools. Proceedings of the 8th ACM CCS International Workshop on Managing Insider Security Threats. :109–112.

Since the number of cyber attacks by insider threats and the damage caused by them has been increasing over the last years, organizations are in need for specific security solutions to counter these threats. To limit the damage caused by insider threats, the timely detection of erratic system behavior and malicious activities is of primary importance. We observed a major paradigm shift towards anomaly-focused detection mechanisms, which try to establish a baseline of system behavior – based on system logging data – and report any deviations from this baseline. While these approaches are promising, they usually have to cope with scalability issues. As the amount of log data generated during IT operations is exponentially growing, high-performance security solutions are required that can handle this huge amount of data in real time. In this paper, we demonstrate how high-performance bioinformatics tools can be leveraged to tackle this issue, and we demonstrate their application to log data for outlier detection, to timely detect anomalous system behavior that points to insider attacks.

Wu, Zuowei, Li, Taoshen.  2017.  An Improved Fully Homomorphic Encryption Scheme Under the Cloud Environment. Proceedings of the 12th Chinese Conference on Computer Supported Cooperative Work and Social Computing. :251–252.
In order to improve the efficiency of the existing homomorphic encryption method, based on the DGHV scheme, an improved fully homomorphic scheme over the integer is proposed. Under the premise of ensuring data owner and user data security, the scheme supports the addition and multiplication operations of ciphertext, and ensures faster execution efficiency and meets the security requirements of cloud computing. Security analysis shows that our scheme is safe. Performance assessment demonstrates that our scheme can more efficiently implement data than DGHV scheme.
Wu, Zhijun, Xu, Enzhong, Liu, Liang, Yue, Meng.  2019.  CHTDS: A CP-ABE Access Control Scheme Based on Hash Table and Data Segmentation in NDN. 2019 18th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/13th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE). :843—848.

For future Internet, information-centric networking (ICN) is considered a potential solution to many of its current problems, such as content distribution, mobility, and security. Named Data Networking (NDN) is a more popular ICN project. However, concern regarding the protection of user data persists. Information caching in NDN decouples content and content publishers, which leads to content security threats due to lack of secure controls. Therefore, this paper presents a CP-ABE (ciphertext policy attribute based encryption) access control scheme based on hash table and data segmentation (CHTDS). Based on data segmentation, CHTDS uses a method of linearly splitting fixed data blocks, which effectively improves data management. CHTDS also introduces CP-ABE mechanism and hash table data structure to ensure secure access control and privilege revocation does not need to re-encrypt the published content. The analysis results show that CHTDS can effectively realize the security and fine-grained access control in the NDN environment, and reduce communication overhead for content access.

Wu, Zhengze, Zhang, Xiaohong, Zhong, Xiaoyong.  2019.  Generalized Chaos Synchronization Circuit Simulation and Asymmetric Image Encryption. IEEE Access. 7:37989–38008.
Generalized chaos systems have more complex dynamic behavior than conventional chaos systems. If a generalized response system can be synchronized with a conventional drive system, the flexible control parameters and unpredictable synchronization state will increase significantly. The study first constructs a four-dimensional nonlinear dynamic equation with quadratic variables as a drive system. The numerical simulation and analyses of the Lyapunov exponent show that it is also a chaotic system. Based on the generalized chaos synchronization (GCS) theory, a four-dimensional diffeomorphism function is designed, and the corresponding GCS response system is generated. Simultaneously, the structural and synchronous circuits of information interaction and control are constructed with Multisim™ software, with the circuit simulation resulting in a good agreement with the numerical calculations. In order to verify the practical effect of generalized synchronization, an RGB digital image secure communication scheme is proposed. We confuse a 24-bit true color image with the designed GCS system, extend the original image to 48-bits, analyze the scheme security from keyspace, key sensitivity and non-symmetric identity authentication, classical types of attacks, and statistical average from the histogram, image correlation. The research results show that this GCS system is simple and feasible, and the encryption algorithm is closely related to the confidential information, which can resist the differential attack. The scheme is suitable to be applied in network images or other multimedia safe communications.
Wu, Zhaoming, Aggarwal, Charu C., Sun, Jimeng.  2016.  The Troll-Trust Model for Ranking in Signed Networks. Proceedings of the Ninth ACM International Conference on Web Search and Data Mining. :447–456.

Signed social networks have become increasingly important in recent years because of the ability to model trust-based relationships in review sites like Slashdot, Epinions, and Wikipedia. As a result, many traditional network mining problems have been re-visited in the context of networks in which signs are associated with the links. Examples of such problems include community detection, link prediction, and low rank approximation. In this paper, we will examine the problem of ranking nodes in signed networks. In particular, we will design a ranking model, which has a clear physical interpretation in terms of the sign of the edges in the network. Specifically, we propose the Troll-Trust model that models the probability of trustworthiness of individual data sources as an interpretation for the underlying ranking values. We will show the advantages of this approach over a variety of baselines.

Wu, Yuming, Liu, Yutao, Liu, Ruifeng, Chen, Haibo, Zang, Binyu, Guan, Haibing.  2018.  Comprehensive VM Protection Against Untrusted Hypervisor Through Retrofitted AMD Memory Encryption. 2018 IEEE International Symposium on High Performance Computer Architecture (HPCA).

The confidentiality of tenant's data is confronted with high risk when facing hardware attacks and privileged malicious software. Hardware-based memory encryption is one of the promising means to provide strong guarantees of data security. Recently AMD has proposed its new memory encryption hardware called SME and SEV, which can selectively encrypt memory regions in a fine-grained manner, e.g., by setting the C-bits in the page table entries. More importantly, SEV further supports encrypted virtual machines. This, intuitively, has provided a new opportunity to protect data confidentiality in guest VMs against an untrusted hypervisor in the cloud environment. In this paper, we first provide a security analysis on the (in)security of SEV and uncover a set of security issues of using SEV as a means to defend against an untrusted hypervisor. Based on the study, we then propose a software-based extension to the SEV feature, namely Fidelius, to address those issues while retaining performance efficiency. Fidelius separates the management of critical resources from service provisioning and revokes the permissions of accessing specific resources from the un-trusted hypervisor. By adopting a sibling-based protection mechanism with non-bypassable memory isolation, Fidelius embraces both security and efficiency, as it introduces no new layer of abstraction. Meanwhile, Fidelius reuses the SEV API to provide a full VM life-cycle protection, including two sets of para-virtualized I/O interfaces to encode the I/O data, which is not considered in the SEV hardware design. A detailed and quantitative security analysis shows its effectiveness in protecting tenant's data from a variety of attack surfaces, and the performance evaluation confirms the performance efficiency of Fidelius.

Wu, Yue.  2016.  Facial Landmark Detection and Tracking for Facial Behavior Analysis. Proceedings of the 2016 ACM on International Conference on Multimedia Retrieval. :431–434.

The face is the most dominant and distinct communication tool of human beings. Automatic analysis of facial behavior allows machines to understand and interpret a human's states and needs for natural interactions. This research focuses on developing advanced computer vision techniques to process and analyze facial images for the recognition of various facial behaviors. Specifically, this research consists of two parts: automatic facial landmark detection and tracking, and facial behavior analysis and recognition using the tracked facial landmark points. In the first part, we develop several facial landmark detection and tracking algorithms on facial images with varying conditions, such as varying facial expressions, head poses and facial occlusions. First, to handle facial expression and head pose variations, we introduce a hierarchical probabilistic face shape model and a discriminative deep face shape model to capture the spatial relationships among facial landmark points under different facial expressions and face poses to improve facial landmark detection. Second, to handle facial occlusion, we improve upon the effective cascade regression framework and propose the robust cascade regression framework for facial landmark detection, which iteratively predicts the landmark visibility probabilities and landmark locations. The second part of this research applies our facial landmark detection and tracking algorithms to facial behavior analysis, including facial action recognition and face pose estimation. For facial action recognition, we introduce a novel regression framework for joint facial landmark detection and facial action recognition. For head pose estimation, we are working on a robust algorithm that can perform head pose estimation under facial occlusion.

Wu, Yingjun, Guo, Wentian, Chan, Chee-Yong, Tan, Kian-Lee.  2017.  Fast Failure Recovery for Main-Memory DBMSs on Multicores. Proceedings of the 2017 ACM International Conference on Management of Data. :267–281.

Main-memory database management systems (DBMS) can achieve excellent performance when processing massive volume of on-line transactions on modern multi-core machines. But existing durability schemes, namely, tuple-level and transaction-level logging-and-recovery mechanisms, either degrade the performance of transaction processing or slow down the process of failure recovery. In this paper, we show that, by exploiting application semantics, it is possible to achieve speedy failure recovery without introducing any costly logging overhead to the execution of concurrent transactions. We propose PACMAN, a parallel database recovery mechanism that is specifically designed for lightweight, coarse-grained transaction-level logging. PACMAN leverages a combination of static and dynamic analyses to parallelize the log recovery: at compile time, PACMAN decomposes stored procedures by carefully analyzing dependencies within and across programs; at recovery time, PACMAN exploits the availability of the runtime parameter values to attain an execution schedule with a high degree of parallelism. As such, recovery performance is remarkably increased. We evaluated PACMAN in a fully-fledged main-memory DBMS running on a 40-core machine. Compared to several state-of-the-art database recovery mechanisms, can significantly reduce recovery time without compromising the efficiency of transaction processing.

Wu, Yifan, Drucker, Steven, Philipose, Matthai, Ravindranath, Lenin.  2018.  Querying Videos Using DNN Generated Labels. Proceedings of the Workshop on Human-In-the-Loop Data Analytics. :6:1–6:6.
Massive amounts of videos are generated for entertainment, security, and science, powered by a growing supply of user-produced video hosting services. Unfortunately, searching for videos is difficult due to the lack of content annotations. Recent breakthroughs in image labeling with deep neural networks (DNNs) create a unique opportunity to address this problem. While many automated end-to-end solutions have been developed, such as natural language queries, we take on a different perspective: to leverage both the development of algorithms and human capabilities. To this end, we design a query language in tandem with a user interface to help users quickly identify segments of interest from the video based on labels and corresponding bounding boxes. We combine techniques from the database and information visualization communities to help the user make sense of the object labels in spite of errors and inconsistencies.
Wu, Yichang, Qiao, Yuansong, Ye, Yuhang, Lee, Brian.  2019.  Towards Improved Trust in Threat Intelligence Sharing using Blockchain and Trusted Computing. 2019 Sixth International Conference on Internet of Things: Systems, Management and Security (IOTSMS). :474–481.
Threat intelligence sharing is posited as an important aid to help counter cybersecurity attacks and a number of threat intelligence sharing communities exist. There is a general consensus that many challenges remain to be overcome to achieve fully effective sharing, including concerns about privacy, negative publicity, policy/legal issues and expense of sharing, amongst others. One recent trend undertaken to address this is the use of decentralized blockchain based sharing architectures. However while these platforms can help increase sharing effectiveness they do not fully address all of the above challenges. In particular, issues around trust are not satisfactorily solved by current approaches. In this paper, we describe a novel trust enhancement framework -TITAN- for decentralized sharing based on the use of P2P reputation systems to address open trust issues. Our design uses blockchain and Trusted Execution Environment technologies to ensure security, integrity and privacy in the operation of the threat intelligence sharing reputation system.
Wu, Yi, Liu, Jian, Chen, Yingying, Cheng, Jerry.  2019.  Semi-black-box Attacks Against Speech Recognition Systems Using Adversarial Samples. 2019 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN). :1—5.
As automatic speech recognition (ASR) systems have been integrated into a diverse set of devices around us in recent years, security vulnerabilities of them have become an increasing concern for the public. Existing studies have demonstrated that deep neural networks (DNNs), acting as the computation core of ASR systems, is vulnerable to deliberately designed adversarial attacks. Based on the gradient descent algorithm, existing studies have successfully generated adversarial samples which can disturb ASR systems and produce adversary-expected transcript texts designed by adversaries. Most of these research simulated white-box attacks which require knowledge of all the components in the targeted ASR systems. In this work, we propose the first semi-black-box attack against the ASR system - Kaldi. Requiring only partial information from Kaldi and none from DNN, we can embed malicious commands into a single audio chip based on the gradient-independent genetic algorithm. The crafted audio clip could be recognized as the embedded malicious commands by Kaldi and unnoticeable to humans in the meanwhile. Experiments show that our attack can achieve high attack success rate with unnoticeable perturbations to three types of audio clips (pop music, pure music, and human command) without the need of the underlying DNN model parameters and architecture.
Wu, Yanjuan, Wang, Haoyue, Yang, Li.  2019.  Research on Modeling Method of Visualized Plane Topology in Electric Power System. 2019 Chinese Control Conference (CCC). :7263–7268.

Aiming at the realization of power system visualization plane topology modeling, a development method of Microsoft Foundation Classes application framework based on Microsoft Visual Studio is proposed. The overall platform development is mainly composed of five modules: the primitive library module, the platform interface module, the model array file module, the topology array file module, and the algorithm module. The software developed by this method can realize the user-defined power system modeling, and can realize power system operation analysis by combining with algorithm. The proposed method has a short development cycle, compatibility and expandability. This method is applied to the development of a plane topology modeling platform for the distribution network system, which further demonstrates the feasibility of this method.

Wu, Yan, Luo, Anthony, Xu, Dianxiang.  2019.  Forensic Analysis of Bitcoin Transactions. 2019 IEEE International Conference on Intelligence and Security Informatics (ISI). :167—169.
Bitcoin [1] as a popular digital currency has been a target of theft and other illegal activities. Key to the forensic investigation is to identify bitcoin addresses involved in bitcoin transfers. This paper presents a framework, FABT, for forensic analysis of bitcoin transactions by identifying suspicious bitcoin addresses. It formalizes the clues of a given case as transaction patterns defined over a comprehensive set of features. FABT converts the bitcoin transaction data into a formal model, called Bitcoin Transaction Net (BTN). The traverse of all bitcoin transactions in the order of their occurrences is captured by the firing sequence of all transitions in the BTN. We have applied FABT to identify suspicious addresses in the Mt.Gox case. A subgroup of the suspicious addresses has been found to share many characteristics about the received/transferred amount, number of transactions, and time intervals.
Wu, Y., Olson, G. F., Peretti, L., Wallmark, O..  2020.  Harmonic Plane Decomposition: An Extension of the Vector-Space Decomposition - Part I. IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society. :985–990.
In this first paper of a two-part series, the harmonic plane decomposition is introduced, which is an extension of the vector-space decomposition. In multiphase electrical machines with variable phase-pole configurations, the vector-space decomposition leads to a varying numbers of vector spaces when changing the configuration. Consequently, the model and current control become discontinuous. The method in this paper is based on samples of each single slot currents, similarly to a discrete Fourier transformation in the space domain that accounts for the winding configuration. It unifies the Clarke transformation for all possible phase-pole configurations such that a fixed number of orthogonal harmonic planes are created, which facilitates the current control during reconfigurations. The presented method is not only limited to the modeling of multiphase electrical machines but all kinds of existing machines can be modeled. In the second part of this series, the harmonic plane decomposition will be completed for all types of machine configurations.
Wu, Y., Lyu, Y., Fang, Q., Zheng, G., Yin, H., Shi, Y..  2017.  Protecting Outsourced Data in Semi-Trustworthy Cloud: A Hierarchical System. 2017 IEEE 37th International Conference on Distributed Computing Systems Workshops (ICDCSW). :300–305.

Data outsourcing in cloud is emerging as a successful paradigm that benefits organizations and enterprises with high-performance, low-cost, scalable data storage and sharing services. However, this paradigm also brings forth new challenges for data confidentiality because the outsourced are not under the physic control of the data owners. The existing schemes to achieve the security and usability goal usually apply encryption to the data before outsourcing them to the storage service providers (SSP), and disclose the decryption keys only to authorized user. They cannot ensure the security of data while operating data in cloud where the third-party services are usually semi-trustworthy, and need lots of time to deal with the data. We construct a privacy data management system appending hierarchical access control called HAC-DMS, which can not only assure security but also save plenty of time when updating data in cloud.

Wu, Y., Li, X., Zou, D., Yang, W., Zhang, X., Jin, H..  2019.  MalScan: Fast Market-Wide Mobile Malware Scanning by Social-Network Centrality Analysis. 2019 34th IEEE/ACM International Conference on Automated Software Engineering (ASE). :139—150.

Malware scanning of an app market is expected to be scalable and effective. However, existing approaches use either syntax-based features which can be evaded by transformation attacks or semantic-based features which are usually extracted by performing expensive program analysis. Therefor, in this paper, we propose a lightweight graph-based approach to perform Android malware detection. Instead of traditional heavyweight static analysis, we treat function call graphs of apps as social networks and perform social-network-based centrality analysis to represent the semantic features of the graphs. Our key insight is that centrality provides a succinct and fault-tolerant representation of graph semantics, especially for graphs with certain amount of inaccurate information (e.g., inaccurate call graphs). We implement a prototype system, MalScan, and evaluate it on datasets of 15,285 benign samples and 15,430 malicious samples. Experimental results show that MalScan is capable of detecting Android malware with up to 98% accuracy under one second which is more than 100 times faster than two state-of-the-art approaches, namely MaMaDroid and Drebin. We also demonstrate the feasibility of MalScan on market-wide malware scanning by performing a statistical study on over 3 million apps. Finally, in a corpus of dataset collected from Google-Play app market, MalScan is able to identify 18 zero-day malware including malware samples that can evade detection of existing tools.

Wu, Xingbo, Ni, Fan, Jiang, Song.  2017.  Search Lookaside Buffer: Efficient Caching for Index Data Structures. Proceedings of the 2017 Symposium on Cloud Computing. :27–39.
With the ever increasing DRAM capacity in commodity computers, applications tend to store large amount of data in main memory for fast access. Accordingly, efficient traversal of index structures to locate requested data becomes crucial to their performance. The index data structures grow so large that only a fraction of them can be cached in the CPU cache. The CPU cache can leverage access locality to keep the most frequently used part of an index in it for fast access. However, the traversal on the index to a target data during a search for a data item can result in significant false temporal and spatial localities, which make CPU cache space substantially underutilized. In this paper we show that even for highly skewed accesses the index traversal incurs excessive cache misses leading to suboptimal data access performance. To address the issue, we introduce Search Lookaside Buffer (SLB) to selectively cache only the search results, instead of the index itself. SLB can be easily integrated with any index data structure to increase utilization of the limited CPU cache resource and improve throughput of search requests on a large data set. We integrate SLB with various index data structures and applications. Experiments show that SLB can improve throughput of the index data structures by up to an order of magnitude. Experiments with real-world key-value traces also show up to 73% throughput improvement on a hash table.
Wu, Xiaotong, Dou, Wanchun, Ni, Qiang.  2017.  Game Theory Based Privacy Preserving Analysis in Correlated Data Publication. Proceedings of the Australasian Computer Science Week Multiconference. :73:1–73:10.

Privacy preserving on data publication has been an important research field over the past few decades. One of the fundamental challenges in privacy preserving data publication is the trade-off problem between privacy and utility of the single and independent data set. However, recent research works have shown that the advanced privacy mechanism, i.e., differential privacy, is vulnerable when multiple data sets are correlated. In this case, the trade-off problem between privacy and utility is evolved into a game problem, in which the payoff of each player is dependent not only on his privacy parameter, but also on his neighbors' privacy parameters. In this paper, we firstly present the definition of correlated differential privacy to evaluate the real privacy level of a single data set influenced by the other data sets. Then, we construct a game model of multiple players, who each publishes the data set sanitized by differential privacy. Next, we analyze the existence and uniqueness of the pure Nash Equilibrium and demonstrate the sufficient conditions in the game. Finally, we refer to a notion, i.e., the price of anarchy, to evaluate efficiency of the pure Nash Equilibrium.

Wu, Xiaohe, Calderon, Juan, Obeng, Morrison.  2021.  Attribution Based Approach for Adversarial Example Generation. SoutheastCon 2021. :1–6.
Neural networks with deep architectures have been used to construct state-of-the-art classifiers that can match human level accuracy in areas such as image classification. However, many of these classifiers can be fooled by examples slightly modified from their original forms. In this work, we propose a novel approach for generating adversarial examples that makes use of only attribution information of the features and perturbs only features that are highly influential to the output of the classifier. We call this approach Attribution Based Adversarial Generation (ABAG). To demonstrate the effectiveness of this approach, three somewhat arbitrary algorithms are proposed and examined. In the first algorithm all non-zero attributions are utilized and associated features perturbed; in the second algorithm only the top-n most positive and top-n most negative attributions are used and corresponding features perturbed; and in the third algorithm the level of perturbation is increased in an iterative manner until an adversarial example is discovered. All of the three algorithms are implemented and experiments are performed on the well-known MNIST dataset. Experiment results show that adversarial examples can be generated very efficiently, and thus prove the validity and efficacy of ABAG - utilizing attributions for the generation of adversarial examples. Furthermore, as shown by examples, ABAG can be adapted to provides a systematic searching approach to generate adversarial examples by perturbing a minimum amount of features.
Wu, Xiaohe, Xu, Jianbo, Huang, Weihong, Jian, Wei.  2020.  A new mutual authentication and key agreement protocol in wireless body area network. 2020 IEEE International Conference on Smart Cloud (SmartCloud). :199—203.

Due to the mobility and openness of wireless body area networks (WBANs), the security of WBAN has been questioned by people. The patient's physiological information in WBAN is sensitive and confidential, which requires full consideration of user anonymity, untraceability, and data privacy protection in key agreement. Aiming at the shortcomings of Li et al.'s protocol in terms of anonymity and session unlinkability, forward/backward confidentiality, etc., a new anonymous mutual authentication and key agreement protocol was proposed on the basis of the protocol. This scheme only uses XOR and the one-way hash operations, which not only reduces communication consumption but also ensures security, and realizes a truly lightweight anonymous mutual authentication and key agreement protocol.

Wu, Xiaoge, Zhang, Lin.  2019.  Robust Chaos-Based Information Masking Polar Coding Scheme for Wiretap Channel in Practical Wireless Systems. 2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall). :1–5.
In practical wireless communication systems, the channel conditions of legitimate users can not always be better than those of eavesdroppers. This realistic fact brings the challenge for the design of secure transmission over wiretap channels which requires that the eavesdropping channel conditions should be worse than legitimate channels. In this paper, we present a robust chaos-based information masking polar coding scheme for enhancing reliability and security performances under realistic channel conditions for practical systems. In our design, we mask the original information, wherein the masking matrix is determined by chaotic sequences. Then the masked information is encoded by the secure polar coding scheme. After the channel polarization achieved by the polar coding, we could identify the bit-channels providing good transmission conditions for legitimate users and the bit-channels with bad conditions for eavesdroppers. Simulations are performed over the additive white Gaussian noise (AWGN) and slow flat-fading Rayleigh channels. The results demonstrate that compared with existing schemes, the proposed scheme can achieve better reliability and security even when the eavesdroppers have better channel conditions than legitimate users, hence the practicability is greatly enhanced.
Wu, Xiaoge, Zhang, Lin.  2019.  Chaos-based Information Rotated Polar Coding Scheme for Visible Light Wiretap Channel. 2019 International Conference on Computing, Networking and Communications (ICNC). :864–868.

In this paper, we present a chaos-based information rotated polar coding scheme for enhancing the reliability and security of visible light communication (VLC) systems. In our scheme, we rotate the original information, wherein the rotation principle is determined by two chaotic sequences. Then the rotated information is encoded by secure polar coding scheme. After the channel polarization achieved by the polar coding, we could identify the bit-channels providing good transmission conditions for legitimate users and the bit-channels with bad conditions for eavesdroppers. Simulations are performed over the visible light wiretap channel. The results demonstrate that compared with existing schemes, the proposed scheme can achieve better reliability and security even when the eavesdroppers have better channel conditions.

Wu, Xi, Li, Fengan, Kumar, Arun, Chaudhuri, Kamalika, Jha, Somesh, Naughton, Jeffrey.  2017.  Bolt-on Differential Privacy for Scalable Stochastic Gradient Descent-based Analytics. Proceedings of the 2017 ACM International Conference on Management of Data. :1307–1322.

While significant progress has been made separately on analytics systems for scalable stochastic gradient descent (SGD) and private SGD, none of the major scalable analytics frameworks have incorporated differentially private SGD. There are two inter-related issues for this disconnect between research and practice: (1) low model accuracy due to added noise to guarantee privacy, and (2) high development and runtime overhead of the private algorithms. This paper takes a first step to remedy this disconnect and proposes a private SGD algorithm to address both issues in an integrated manner. In contrast to the white-box approach adopted by previous work, we revisit and use the classical technique of output perturbation to devise a novel “bolt-on” approach to private SGD. While our approach trivially addresses (2), it makes (1) even more challenging. We address this challenge by providing a novel analysis of the L2-sensitivity of SGD, which allows, under the same privacy guarantees, better convergence of SGD when only a constant number of passes can be made over the data. We integrate our algorithm, as well as other state-of-the-art differentially private SGD, into Bismarck, a popular scalable SGD-based analytics system on top of an RDBMS. Extensive experiments show that our algorithm can be easily integrated, incurs virtually no overhead, scales well, and most importantly, yields substantially better (up to 4X) test accuracy than the state-of-the-art algorithms on many real datasets.

Wu, X., Xiao, J., Shao, J..  2017.  Trust-Based Protocol for Securing Routing in Opportunistic Networks. 2017 13th IEEE Conference on Automation Science and Engineering (CASE). :434–439.

It is hard to set up an end-to-end connection between source and destination in Opportunistic Networks, due to dynamic network topology and the lack of infrastructure. Instead, the store-carry-forward mechanism is used to achieve communication. Namely, communication in Opportunistic Networks relies on the cooperation among nodes. Correspondingly, Opportunistic Networks have some issues like long delays, packet loss and so on, which lead to many challenges in Opportunistic Networks. However, malicious nodes do not follow the routing rules, or refuse to cooperate with benign nodes. Some misbehaviors like black-hole attack, gray-hole attack may arbitrarily bloat their delivery competency to intercept and drop data. Selfishness in Opportunistic Networks will also drop some data from other nodes. These misbehaviors will seriously affect network performance like the delivery success ratio. In this paper, we design a Trust-based Routing Protocol (TRP), combined with various utility algorithms, to more comprehensively evaluate the competency of a candidate node and effectively reduce negative effects by malicious nodes. In simulation, we compare TRP with other protocols, and shows that our protocol is effective for misbehaviors.