Ali Chehab - Academia.edu (original) (raw)

Papers by Ali Chehab

Frontiers in Communications and Networks, 2021

The COVID-19 pandemic has attracted the attention of big data analysts and artificial intelligenc... more The COVID-19 pandemic has attracted the attention of big data analysts and artificial intelligence engineers. The classification of computed tomography (CT) chest images into normal or infected requires intensive data collection and an innovative architecture of AI modules. In this article, we propose a platform that covers several levels of analysis and classification of normal and abnormal aspects of COVID-19 by examining CT chest scan images. Specifically, the platform first augments the dataset to be used in the training phase based on a reliable collection of images, segmenting/detecting the suspicious regions in the images, and analyzing these regions in order to output the right classification. Furthermore, we combine AI algorithms, after choosing the best fit module for our study. Finally, we show the effectiveness of this architecture when compared to other techniques in the literature. The obtained results show that the accuracy of the proposed architecture is 95%.

We introduce a new deterministic parallel sorting algorithm for distributed memory machines based... more We introduce a new deterministic parallel sorting algorithm for distributed memory machines based on the regular sampling approach. The algorithm uses only two rounds of regular all-to-all personalized communication in a scheme that yields very good load balancing with virtually no overhead. Moreover, unlike previous variations, our algorithm efficiently handles the presence of duplicate values without the overhead of tagging each element with a unique identifier. This algorithm was implemented in SPLIT-C and run on a variety of platforms, including the Thinking Machines CM-5, the IBM SP-2-WN, and the Cray Research T3D. We ran our code using widely different benchmarks to examine the dependence of our algorithm on the input distribution. Our experimental results illustrate the efficiency and scalability of our algorithm across different platforms. In fact, the performance compares closely to that of our random sample sort algorithm, which seems to outperform all similar algorithms known to the authors on these platforms. Together, their performance is nearly invariant over the set of input distributions, unlike previous efficient algorithms. However, unlike our randomized sorting algorithm, the performance and memory requirements of our regular sorting algorithm can be deterministically guaranteed. We present a novel variation on the approach of sorting by regular sampling which leads to a new deterministic sorting algorithm that achieves optimal computational speedup with very little communication. Our algorithm exchanges the single step of irregular communication used by previous implementations for two steps of regular communication. In return, our algorithm mitigates the problem of poor load balancing because it is able to sustain a high sampling rate at substantially less cost. In addition, our algorithm efficiently accommodates the presence of duplicates without the overhead of tagging each element. And our algorithm achieves predictable, regular communication requirements which are essentially invariant with respect to the input distribution. Utilizing regular communication has become more important with the advent of message passing standards, such as MPI [16], which seek to guarantee the availability of very efficient (often machine specific) implementations of certain basic collective communication routines. Our algorithm was implemented in a high-level language and run on a variety of platforms, including the Thinking Machines CM-5, the IBM SP-2, and the Cray Research T3D. We ran our code using a variety of benchmarks that we identified to examine the dependence of our algorithm on the input distribution. Our experimental results are consistent with the theoretical analysis and illustrate the efficiency and scalability of our algorithm across different platforms. In fact, the performance compares closely to that of our random sample sort algorithm, which seems to outperform all similar algorithms known to the authors on these platforms. Together, their performance is nearly indifferent to the set of input distributions, unlike previous efficient algorithms. However, unlike our randomized sorting algorithm, the performance and memory requirements of our regular sorting algorithm can be guaranteed with deterministically. The high-level language used in our studies is SPLIT-C [10], an extension of C for distributed memory machines. The algorithm makes use of MPI-like communication primitives but does not make any assumptions as to how these primitives are actually implemented. The basic data transport is a read or write operation. The remote read and write typically have both blocking and non-blocking versions. Also, when reading or writing more than a single element, bulk data transports are provided with corresponding bulk read and bulk write primitives. Our collective communication primitives, described in detail in [4], are similar to those of the MPI [16], the IBM POWERparallel [6], and the Cray MPP systems [9] and, for example, include the following: transpose, bcast, gather, and scatter. Brief descriptions of these are as follows. The transpose primitive is an all-to-all personalized communication in which each processor has to send a unique block of data to every processor, and all the blocks are of the same size. The bcast primitive is used to copy a block of data from a single source to all the other processors. The primitives gather and scatter are companion primitives. Scatter divides a single array residing on a processor into equal-sized blocks, each of which is distributed to a unique processor, and gather coalesces these blocks back into a single array at a particular processor. See [3, 4, 5] for algorithmic details, performance analyses, and empirical results for these communication primitives. The organization of this paper is as follows. Section 2 presents our computation model for analyzing parallel algorithms. Section 3 describes in detail our improved sample sort algorithm. Finally, Section 4 describes our data sets and the experimental performance of our sorting algorithm.

Honorary Conference Chair

Journal of Sensor and Actuator Networks

Statistical traffic analysis has absolutely exposed the privacy of supposedly secure network traf... more Statistical traffic analysis has absolutely exposed the privacy of supposedly secure network traffic, proving that encryption is not effective anymore. In this work, we present an optimal countermeasure to prevent an adversary from inferring users’ online activities, using traffic analysis. First, we formulate analytically a constrained optimization problem to maximize network traffic obfuscation while minimizing overhead costs. Then, we provide OPriv, a practical and efficient algorithm to solve dynamically the non-linear programming (NLP) problem, using Cplex optimization. Our heuristic algorithm selects target applications to mutate to and the corresponding packet length, and subsequently decreases the security risks of statistical traffic analysis attacks. Furthermore, we develop an analytical model to measure the obfuscation system’s resilience to traffic analysis attacks. We suggest information theoretic metrics for quantitative privacy measurement, using entropy. The full pri...

Int. J. Netw. Secur., 2009

Web Services are widely used to provide services and exchange data among business units, customer... more Web Services are widely used to provide services and exchange data among business units, customers, partners and suppliers for enterprises. Although Web Services signiflcantly improve the interaction and development of processes in the business world, they raise several security concerns, since they greatly increase the exposure of critical enterprise data. Web Services exchange data using SOAP messages that are based on the interoperable XML language. We have previously introduced XPRIDE as an enhanced security architecture for assuring confldentiality and integrity of SOAP messages. XPRIDE uses contentbased encryption to secure SOAP messages based on their XML content, and depends on security policies to deflne the parts of the SOAP message that need to be encrypted. Security policies are deflned by administrators for each Web Service that needs to be secured. This paper extends XPRIDE using a modular design approach to ensure extensibility, such that new modules can be developed ...

ArXiv, 2019

In this work, a novel target detector for hyperspectral imagery is developed. The detector is ind... more In this work, a novel target detector for hyperspectral imagery is developed. The detector is independent on the unknown covariance matrix, behaves well in large dimensions, distributional free, invariant to atmospheric effects, and does not require a background dictionary to be constructed. Based on a modification of the robust principal component analysis (RPCA), a given hyperspectral image (HSI) is regarded as being made up of the sum of a low-rank background HSI and a sparse target HSI that contains the targets based on a pre-learned target dictionary specified by the user. The sparse component is directly used for the detection, that is, the targets are simply detected at the non-zero entries of the sparse target HSI. Hence, a novel target detector is developed, which is simply a sparse HSI generated automatically from the original HSI, but containing only the targets with the background is suppressed. The detector is evaluated on real experiments, and the results of which demo...

Int. J. Netw. Secur., 2006

This paper presents PATRIOT, an optimized, policydriven security architecture for protecting the ... more This paper presents PATRIOT, an optimized, policydriven security architecture for protecting the confidentiality and integrity of audit log files on wireless devices. PATRIOT is based on a set of well-known cryptographic protocols and is designed to suit the limited nature of wireless devices. It offers a policy-driven, customizable security model and specifies a flexible, multi-level, and fine-grained encryption methodology that provides the suitable security strength without compromising performance. PATRIOT is designed in a platform-neutral manner and it can be deployed on a wide range of wireless devices and operating systems.

Security analysis of drones systems: Attacks, limitations, and recommendations

Internet of Things

IEEE Transactions on Communications

A family of low-complexity detection schemes based on channel matrix puncturing targeted for larg... more A family of low-complexity detection schemes based on channel matrix puncturing targeted for large multiple-input multiple-output (MIMO) systems is proposed. It is well-known that the computational cost of MIMO detection based on QR decomposition is directly proportional to the number of nonzero entries involved in back-substitution and slicing operations in the triangularized channel matrix, which can be too high for low-latency applications involving large MIMO dimensions. By systematically puncturing the channel to have a specific structure, it is demonstrated that the detection process can be accelerated by employing standard schemes such as chase detection, list detection, nulling-andcancellation detection, and sub-space detection on the transformed matrix. The performance of these schemes is characterized and analyzed mathematically, and bounds on the achievable diversity gain and probability of bit error are derived. Surprisingly, it is shown that puncturing does not negatively impact the receive diversity gain in hard-output detectors. The analysis is extended to soft-output detection when computing per-layer bit log-likelihood ratios; it is shown that significant performance gains are attainable by ordering the layer of interest to be at the root when puncturing the channel. Simulations of coded and uncoded scenarios certify that the proposed schemes scale up efficiently both in the number of antennas and constellation size, as well as in the presence of correlated channels. In particular, softoutput per-layer sub-space detection is shown to achieve a 2.5 dB SNR gain at 10 −4 bit error rate in 256-QAM 16×16 MIMO, while saving 77% of nulling-and-cancellation computations.

Electrical and Computer Engineering, American University of Beirut, Beirut 1107 2020, Lebanon

ICC'12 CISS: IEEE ICC 2012-Communication and Information Systems Security Symposium-Committees and Welcome

Computer Networks

Recently, there has been an increasing interest in the Internet of Things (IoT). While some analy... more Recently, there has been an increasing interest in the Internet of Things (IoT). While some analysts disvalue the IoT hype, several technology leaders, governments, and researchers are putting serious efforts to develop solutions enabling wide IoT deployment. Thus, the huge amount of generated data, the high network scale, the security and privacy concerns, the new requirements in terms of QoS, and the heterogeneity in this ubiquitous network of networks make its implementation a very challenging task. SDN, a new networking paradigm, has revealed its usefulness in reducing the management complexities in today's networks. Additionally, SDN, having a global view of the network, has presented effective security solutions. On the other hand, fog computing, a new data service platform, consists of pushing the data to the network edge reducing the cost (in terms of bandwidth consumption and high latency) of "big data" transportation through the core network. In this paper, we critically review the SDN and fog computingbased solutions to overcome the IoT main challenges, highlighting their advantages, and exposing their weaknesses. Thus, we make recommendations at the end of this paper for the upcoming research work.

Efficient data confidentiality scheme for 5G wireless NOMA communications

Journal of Information Security and Applications

AdaptiveMutate: A technique for privacy preservation

Digital Communications and Networks

On-demand network virtualization and provisioning services in SDN-driven cloud platforms

Network as a Service for Next Generation Internet

International Journal of RFID Security and Cryptography, 2013

Radio Frequency Identification (RFID) is a technology used for automatic identification of object... more Radio Frequency Identification (RFID) is a technology used for automatic identification of objects, people, and virtually anything one can think of. Applications of RFID technology are expanding and its usage is being adopted worldwide. As such, major efforts have been made to secure the communications in RFID systems and to protect them from various attacks. This paper surveys RFID systems, citing some of their applications as well as the numerous security vulnerabilities they suffer from. Then, some of the proposed solutions that guard against these vulnerabilities are presented and discussed. Then, a novel approach to achieve mutual authentication for ultra-lightweight tags is proposed using Physically Unclonable Functions (PUFs). The proposed approach provides robust security properties as well as good performance characteristics. A proof of concept implementation of the proposed protocol was done on Java programming language that proved the feasibility and efficiency of the protocol.

This paper presents SPARTA (Secure, Policy-driven, ARchitecture for content disTribution and stor... more This paper presents SPARTA (Secure, Policy-driven, ARchitecture for content disTribution and storAge), a secure, policy-driven architecture for enterprise applications operating in centralized wireless environments. SPARTA supports end-to-end client authentication, data integrity and confidentiality. The security services provided by SPARTA are customized and controlled by easily configurable security policies which specify several security-related attributes, classify network and locally-stored data based on sensitivity and content, and provide an abstraction for the communication and messaging between the client and the server. In addition, SPARTA provides a standard Application Programming Interface (API) that conceals to a great extent the complexity of security operations and programming from the application. SPARTA was designed in a platform-neutral manner and can be implemented on a wide range of wireless clients ranging from low-end platforms such as the Java 2 Mobile Edition/Connected Limited Device Configuration (J2ME/CLDC) on limited-memory mobile devices to Personal Java and the .Net Compact Framework on PDAs. On the server side, SPARTA can be implemented on any of the available enterprise server platforms. A sample implementation of SPARTA was developed for J2ME on the client-side and Java 2 Enterprise Edition (J2EE) on the serverside.

Given the accelerated growth in tablet devices, smartphones, and netbooks, designers are faced wi... more Given the accelerated growth in tablet devices, smartphones, and netbooks, designers are faced with serious challenges to meet the needs of mobility in terms of battery life and form factor. It is vital to investigate how to deliver the best mobile experience to users while ensuring adequate levels of performance. In this paper, we present a power management evaluation of multi-core processor systems by comparing thermal power, battery life, and performance when running different types of workloads under a limited number of cores. To show the potential gains from a system power management perspective, we have assessed a mobile platform featuring the Second Generation Intel Core i5 processor, and tested it on a wide selection of workloads and benchmarks. Experimental results show significant thermal power reduction (up to 40 %) in a variety of scenarios, while system performance was sustained in most cases but sacrificed in a few other uncommon situations.

Original research paper: Fuzzy reputation-based trust model

Applied Soft Computing, 2011