ِAmr Y O U S S E F Bakla (original) (raw)
Papers by ِAmr Y O U S S E F Bakla
Lecture Notes in Computer Science, 2001
At ACISP 2000, Yoo et al proposed a fast public key cryptosystem using matrices over a ring. The ... more At ACISP 2000, Yoo et al proposed a fast public key cryptosystem using matrices over a ring. The authors claim that the security of their system is based on the RSA problem. In this paper we present a heuristic attack that enables us to recover the private key from the public key. In particular, we show that breaking the system can be reduced to finding a short vector in a lattice which can be achieved using the L 3-lattice reduction algorithm.
IET Cyber-Physical Systems: Theory & Applications, 2021
A covert channel is a communication channel that is not intended to exist, and that can be used t... more A covert channel is a communication channel that is not intended to exist, and that can be used to transfer information in a manner that violates the system security policy. Attackers can abuse such channel to exfiltrate sensitive information from cyber-physical systems (CPSs), e.g., to leak the confidential or proprietary parameters in a control system. Furthermore, attacks against CPSs can exploit the leaked information about the implementation of the control system, e.g., to determine optimal false data injection attack values that degrade the system performance while remaining undetected. In this paper, we present a control theoretic approach for establishing covert channels in stochastic CPSs. In particular, we consider a scenario where an attacker is able to inject malware into the networked controller and arbitrarily alter the control logic. By exploiting such capability, an attacker can establish an illegitimate communication channel, e.g., to transmit sensitive plant parameters, between the networked controller and an eavesdropper intercepting the sensor measurements. We show that such a channel can be established by exploiting the closed-loop system operations, a decoding mechanism based on an unknown input observer, and an error-correcting coding scheme that exploits the control loop to obtain an implicit acknowledgement. A simple proof of concept implementation of the covert channel is presented, and its performance is evaluated by resorting to a numerical example. Finally, we propose some defences and countermeasures against the proposed covert channel.
Roloff/Matek Maschinenelemente Formelsammlung, 2021
Open Access Library Journal, 2021
In today’s business environment, companies are facing increased pressure from different sources, ... more In today’s business environment, companies are facing increased pressure from different sources, such as consumers and communities, stricter governmental regulations and scarcity of resources; to enhance their sustainable behavior. This escalating global awareness of the impact of manufacturing and operational processes on the environment has translated into increased managerial action to balance incorporates economic, financial and environmental performance. Green Supply Chain Management (GSCM) has emerged as an important organizational philosophy to achieve targeted economic and market objectives while reducing environmental risk, reducing cost, optimizing resources and enhancing operations throughout the supply chain. Green supply chain management practices, activities, and their impact on different aspects of corporate performance have been gaining increased attention from academia, industry and customers. The current research aims to investigate the effect of GSCM practices; Gr...
2020 IEEE 9th International Conference on Cloud Networking (CloudNet), 2020
In this paper, we propose a lightweight mutual authentication and inter-cloud redeemable payment ... more In this paper, we propose a lightweight mutual authentication and inter-cloud redeemable payment protocol which allows IoT devices to subscribe with their home cloud service providers for roaming coverage. More precisely, such devices acquire authenticated payment tokens in order to benefit from the computation offloading services from edge nodes deployed by foreign cloud service providers. Hence, IoT devices are continuously serviced even when outside of their home cloud providers coverage. The protocol makes use of tree of secrets, hash chains, and Merkle trees. It requires sharing a Merkle tree root and a 128-bit secret key for constructing the tree of secrets among cloud admins. Our protocol provides mutual authentication, confidentiality, and easy charge redemption from the home server. For N subscribed IoT devices, the storage at the hosting clouds is limited to 2 × (Ns + 1) × 16 bytes and 32 × Log N bytes for the IoT device, where Ns is the maximum number of devices served by the IoT gateway per payment redemption period.
Cureus, 2021
Pulmonary hypertension (PH) in patients with chronic obstructive pulmonary disease (COPD) is asso... more Pulmonary hypertension (PH) in patients with chronic obstructive pulmonary disease (COPD) is associated with an increase in the risk of COPD exacerbation, increased hospitalization, and worse survival in this patient population. No specific treatment is available for PH in COPD. However, reported out-of-proportion PH may benefit from a certain type of treatment. This study shows that the use of selexipag in the treatment of out-of-proportion PH in COPD patients was associated with an improvement in functional status evaluated by a six-minute walk test (6MWT) and a mean pulmonary artery pressure at 6 +/- 2 months of treatment.
OALib, 2019
The current research aims to propose a framework of the effects of Executive Compensation on Fina... more The current research aims to propose a framework of the effects of Executive Compensation on Financial Performance, measuring the size of effect, the circumstances under which the effect is clearly observed and studying the weighted effect of Executive Compensation on the Performance of firms; ROA, ROE, Tobin's Q turning out with the outcome emphasizing whether the Executive Compensation has a significant or an insignificant role. The research sample is the top listed 50 companies in the Egyptian market which are collected as secondary data from Egypt Stock Exchange. The contribution in this research arises from measuring executive compensation role in firms of Egypt. The research tackles the whole status of the firms in Egypt during the period from 2012 to 2017. Results showed that the main hypothesis of this research that, Executive Compensation on Firm Performance is partially supported.
Angiology, Jan 23, 2016
We assessed the very long-term follow-up of a large cohort of unselected patients treated with co... more We assessed the very long-term follow-up of a large cohort of unselected patients treated with coronary rotational atherectomy (RA). All 143 patients who underwent RA at our institution from 2000 to 2013 and with complete baseline and follow-up information were analyzed in a retrospective manner. Major adverse cardiac events (MACE) were defined as the composite of target vessel revascularization (TVR), acute myocardial infarction, and all-cause mortality. The mean follow-up was 8.2 years. The 10-year cumulative incidence of MACE for all patients was 57.9% (standard error [SE]: 5.0%). When comparing patients who received a drug-eluting stent (DES; n = 68) versus patients who did not (balloon only, bare-metal stent, or none of the aforementioned; n = 75), the RA + DES demonstrated very long-term MACE of 49.2% (SE: 7.5%) versus 62.7% (SE: 6.1%), P = .160 with TVR as the most discriminating factor, 10.7% (SE: 4.0%) versus 29.2% (SE: 6.0%), P = .016. Our results point to RA having reason...
ESC Heart Failure, 2015
Aims Our aim is to describe the clinical characteristics and management of patients hospitalized ... more Aims Our aim is to describe the clinical characteristics and management of patients hospitalized with acute heart failure (HHF) and ambulatory patients with chronic heart failure (CHF) in Egypt and compare them with heart failure (HF) patients from other countries in the European Society of Cardiology-Heart Failure (ESC-HF) registry. Methods and results The ESC-HF Long-term Registry is a prospective, multi-centre, observational study of patients presenting to cardiology centres in member countries of the ESC. From April 2011 to February 2014, a total of 2145 patients with HF were recruited from 20 centres all over Egypt. Of these patients, 1475 (68.8%) were hospitalized with HHF, while 670 (31.2%) had CHF. Less than one-third (32.1%) of all patients were females. HHF patients {median age of 61 years [interquartile range (IQR), 53-69]} were older than CHF patients [median age of 57 years (IQR,46-64)]; P < 0.0001. They had more diabetes mellitus (45.4% vs. 31.8%; P < 0.0001). Left ventricular ejection fraction > 45% was present in 22% of HHF vs. 25.6% of CHF (P = 0.17). Atrial fibrillation existed in about a quarter of all patients (24.5%). Ischaemic heart disease was the main cause of HF in Egyptian patients. All-cause in-hospital mortality was 5%. Egyptian patients presented at a much earlier age than in other regions in the registry. They had more diabetes mellitus. Atrial fibrillation prevalence was remarkably lower. Other co-morbidities (renal dysfunction, stroke, and peripheral arterial disease) occurred less frequently. Conclusion Patients in the Egyptian cohort exhibited distinct features from HF patients in other countries in the ESC-HF Long-term Registry.
Lecture Notes in Computer Science, 2001
Cryptographic Boolean functions should have large distance to functions with simple algebraic des... more Cryptographic Boolean functions should have large distance to functions with simple algebraic description to avoid cryptanalytic attacks based on successive approximation of the round function such as the interpolation attack. Hyper-bent functions achieve the maximal minimum distance to all the coordinate functions of all bijective monomials. However, this class of functions exists only for functions with even number of inputs. In this paper we provide some constructions for Boolean functions with odd number of inputs that achieve large distance to all the coordinate functions of all bijective monomials.
The Egyptian Heart Journal, 2011
Background: The aim of this study was to investigate the effect of ivabradine on symptoms, qualit... more Background: The aim of this study was to investigate the effect of ivabradine on symptoms, quality of life, effort tolerance, and echocardiographic parameters in patients with idiopathic dilated cardiomyopathy presenting with New York Heart Association (NYHA) class III or IV heart failure (HF) symptoms. Methods: We screened 167 patients hospitalized for NYHA class III or IV chronic HF symptoms and left ventricular (LV) ejection fraction <40%. Of these, 53 were randomly assigned to either guidelines-based medical therapy alone (23 patients, control group) or ivabradine as add-on therapy (30 patients) for 3 months with about 1 year follow up. Results: After 3 months' treatment, adding ivabradine significantly reduced the heart rate from 96 to 72 bpm (p < 0.0001 versus control group), with more improvement in echocardiographic LV dimensions, LV volumes, LV ejection fraction (p = 0.045), NYHA class symptoms (p = 0.004), exercise tolerance (p = 0.03), and quality of life (p = 0.02). The average number of hospitalizations for HF over a mean longer-term follow-up of 13.5 months was 1.0 ± 1.4 in the ivabradine group versus 2.1 ± 1.1 in the control group (p = 0.003
2007 Canadian Conference on Electrical and Computer Engineering, 2007
In this paper an incremental version of line tangent space alignment (LTSA) is proposed on the ba... more In this paper an incremental version of line tangent space alignment (LTSA) is proposed on the basis of incremental locally linear embedding (LLE) generalizations and the subsequent incremental Hessian locally linear embedding (HLLE). The main goal of this algorithm is to reduce the dimensionality of high-dimension manifolds into a lower dimension representation such that the significant characteristics of the dataset
2008 Canadian Conference on Electrical and Computer Engineering, 2008
Boolean functions play a major role in the construction of symmetric key primitives such as block... more Boolean functions play a major role in the construction of symmetric key primitives such as block ciphers, stream ci-phers and hash functions. The security of these primitives depends on the cryptographic properties of the Boolean func-tions used in its construction. Various ...
2006 Canadian Conference on Electrical and Computer Engineering, 2006
In this paper, we investigate the use of Ant Colony Optimization (ACO) for automated cryptanalysi... more In this paper, we investigate the use of Ant Colony Optimization (ACO) for automated cryptanalysis of classical simple substitution ciphers. Based on our experiments, ACO-based attacks proved to be very effective on various sets of encoding keys.
2006 Canadian Conference on Electrical and Computer Engineering, 2006
Feature selection is an important research problem in different statistical learning problems inc... more Feature selection is an important research problem in different statistical learning problems including text categorization applications such as spam email classification. In designing spam filters, we often represent the email by vector space model (VSM), i.e., every email is considered as a vector of word terms. Since there are many different terms in the email, and not all classifiers can handle such a high dimension, only the most powerful discriminatory terms should be used. Another reason is that some of these features may not be influential and might carry redundant information which may confuse the classifier. Thus, feature selection, and hence dimensionality reduction, is a crucial step to get the best out of the constructed features. There are many feature selection strategies that can be applied to produce the resulting feature set. In this paper, we investigate the use of Hill Climbing, Simulated Annealing, and Threshold Accepting optimization techniques as feature selection algorithms. We also compare the performance of the above three techniques with the Linear Discriminate Analysis. Our experiment results show that all these techniques can be used not only to reduce the dimensions of the e-mail, but also improve the performance of the classification filter. Among all the strategies, simulated annealing has the best performance which reaches a classification accuracy of 95.5%.
The Indian Journal of Pediatrics, 2011
Objectives To compare T-cell function in healthy/septic preterms in relation to healthy term babi... more Objectives To compare T-cell function in healthy/septic preterms in relation to healthy term babies. Also to determine correlation of sepsis severity with T-cell function and risk to candidal infection. Methods Patients were recruited to one of three groups. Group (I) included 30 healthy growing preterms, group (II) included preterms with neonatal sepsis whereas group (III) included 30 healthy full term neonates. Patients underwent history taking and comprehensive examination plus laboratory tests including T-Lymphocyte function by blastoid transformation method using phytohaemagglutinin (PHA). Results A significant difference exists between healthy preterm vs. septic newborn T cell counts and functions especially those with multiorgan system failure. No correlation was found between candidal infection and T cell functions. Conclusions T cell functions are remarkably lower in septic newborns. Septic preterms may have low T cell functions despite absence of lymphopenia. Early detection is advised to improve outcome.
2011 seventh International Computer Engineering Conference (ICENCO'2011), 2011
In this paper, we focus on two main properties of random sequences; Hamming correlation (HC), and... more In this paper, we focus on two main properties of random sequences; Hamming correlation (HC), and linear span (LS). We study these properties for RC4 stream cipher, a family built on M-sequences, and sequences generated by Reed - Solomon Code.
Information Security Journal: A Global Perspective, 2012
Honeypots are network surveillance architectures designed to resemble easy-to-compromise computer... more Honeypots are network surveillance architectures designed to resemble easy-to-compromise computer systems. They are deployed with the aim to trap hackers in order to help security professionals capture, control, and analyze malicious Internet attacks and other activities of hackers. A botnet is an army of compromised computers controlled by a bot herder and used for illicit financial gain. Botnets have become quite popular in recent Internet attacks. Since honeypots have been deployed in many defense systems, attackers constructing and maintaining botnets are forced to find ways to avoid honeypot traps. In fact, some researchers have even suggested equipping normal machines by misleading evidence so that they appear as honeypots in order to scare away rational attackers. In this paper, we address some aspects related to the problem of honeypot detection by botmasters. In particular, we show that current honeypot architectures and operation limitations may allow attackers to systematically collect, combine and analyze evidence about the true nature of the machines they compromise. In particular, we show how a systematic technique for evidence combining such as Dempster-Shafer theory can allow botmasters to determine the true nature of compromised machines with a relatively high certainty. The obtained results demonstrate inherent limitations of current honeypot designs. We also aim to draw the attention of security professionals to work on enhancing the discussed features of honeypots in order to prevent them from being abused by botmasters.
Lecture Notes in Computer Science, 2001
At ACISP 2000, Yoo et al proposed a fast public key cryptosystem using matrices over a ring. The ... more At ACISP 2000, Yoo et al proposed a fast public key cryptosystem using matrices over a ring. The authors claim that the security of their system is based on the RSA problem. In this paper we present a heuristic attack that enables us to recover the private key from the public key. In particular, we show that breaking the system can be reduced to finding a short vector in a lattice which can be achieved using the L 3-lattice reduction algorithm.
IET Cyber-Physical Systems: Theory & Applications, 2021
A covert channel is a communication channel that is not intended to exist, and that can be used t... more A covert channel is a communication channel that is not intended to exist, and that can be used to transfer information in a manner that violates the system security policy. Attackers can abuse such channel to exfiltrate sensitive information from cyber-physical systems (CPSs), e.g., to leak the confidential or proprietary parameters in a control system. Furthermore, attacks against CPSs can exploit the leaked information about the implementation of the control system, e.g., to determine optimal false data injection attack values that degrade the system performance while remaining undetected. In this paper, we present a control theoretic approach for establishing covert channels in stochastic CPSs. In particular, we consider a scenario where an attacker is able to inject malware into the networked controller and arbitrarily alter the control logic. By exploiting such capability, an attacker can establish an illegitimate communication channel, e.g., to transmit sensitive plant parameters, between the networked controller and an eavesdropper intercepting the sensor measurements. We show that such a channel can be established by exploiting the closed-loop system operations, a decoding mechanism based on an unknown input observer, and an error-correcting coding scheme that exploits the control loop to obtain an implicit acknowledgement. A simple proof of concept implementation of the covert channel is presented, and its performance is evaluated by resorting to a numerical example. Finally, we propose some defences and countermeasures against the proposed covert channel.
Roloff/Matek Maschinenelemente Formelsammlung, 2021
Open Access Library Journal, 2021
In today’s business environment, companies are facing increased pressure from different sources, ... more In today’s business environment, companies are facing increased pressure from different sources, such as consumers and communities, stricter governmental regulations and scarcity of resources; to enhance their sustainable behavior. This escalating global awareness of the impact of manufacturing and operational processes on the environment has translated into increased managerial action to balance incorporates economic, financial and environmental performance. Green Supply Chain Management (GSCM) has emerged as an important organizational philosophy to achieve targeted economic and market objectives while reducing environmental risk, reducing cost, optimizing resources and enhancing operations throughout the supply chain. Green supply chain management practices, activities, and their impact on different aspects of corporate performance have been gaining increased attention from academia, industry and customers. The current research aims to investigate the effect of GSCM practices; Gr...
2020 IEEE 9th International Conference on Cloud Networking (CloudNet), 2020
In this paper, we propose a lightweight mutual authentication and inter-cloud redeemable payment ... more In this paper, we propose a lightweight mutual authentication and inter-cloud redeemable payment protocol which allows IoT devices to subscribe with their home cloud service providers for roaming coverage. More precisely, such devices acquire authenticated payment tokens in order to benefit from the computation offloading services from edge nodes deployed by foreign cloud service providers. Hence, IoT devices are continuously serviced even when outside of their home cloud providers coverage. The protocol makes use of tree of secrets, hash chains, and Merkle trees. It requires sharing a Merkle tree root and a 128-bit secret key for constructing the tree of secrets among cloud admins. Our protocol provides mutual authentication, confidentiality, and easy charge redemption from the home server. For N subscribed IoT devices, the storage at the hosting clouds is limited to 2 × (Ns + 1) × 16 bytes and 32 × Log N bytes for the IoT device, where Ns is the maximum number of devices served by the IoT gateway per payment redemption period.
Cureus, 2021
Pulmonary hypertension (PH) in patients with chronic obstructive pulmonary disease (COPD) is asso... more Pulmonary hypertension (PH) in patients with chronic obstructive pulmonary disease (COPD) is associated with an increase in the risk of COPD exacerbation, increased hospitalization, and worse survival in this patient population. No specific treatment is available for PH in COPD. However, reported out-of-proportion PH may benefit from a certain type of treatment. This study shows that the use of selexipag in the treatment of out-of-proportion PH in COPD patients was associated with an improvement in functional status evaluated by a six-minute walk test (6MWT) and a mean pulmonary artery pressure at 6 +/- 2 months of treatment.
OALib, 2019
The current research aims to propose a framework of the effects of Executive Compensation on Fina... more The current research aims to propose a framework of the effects of Executive Compensation on Financial Performance, measuring the size of effect, the circumstances under which the effect is clearly observed and studying the weighted effect of Executive Compensation on the Performance of firms; ROA, ROE, Tobin's Q turning out with the outcome emphasizing whether the Executive Compensation has a significant or an insignificant role. The research sample is the top listed 50 companies in the Egyptian market which are collected as secondary data from Egypt Stock Exchange. The contribution in this research arises from measuring executive compensation role in firms of Egypt. The research tackles the whole status of the firms in Egypt during the period from 2012 to 2017. Results showed that the main hypothesis of this research that, Executive Compensation on Firm Performance is partially supported.
Angiology, Jan 23, 2016
We assessed the very long-term follow-up of a large cohort of unselected patients treated with co... more We assessed the very long-term follow-up of a large cohort of unselected patients treated with coronary rotational atherectomy (RA). All 143 patients who underwent RA at our institution from 2000 to 2013 and with complete baseline and follow-up information were analyzed in a retrospective manner. Major adverse cardiac events (MACE) were defined as the composite of target vessel revascularization (TVR), acute myocardial infarction, and all-cause mortality. The mean follow-up was 8.2 years. The 10-year cumulative incidence of MACE for all patients was 57.9% (standard error [SE]: 5.0%). When comparing patients who received a drug-eluting stent (DES; n = 68) versus patients who did not (balloon only, bare-metal stent, or none of the aforementioned; n = 75), the RA + DES demonstrated very long-term MACE of 49.2% (SE: 7.5%) versus 62.7% (SE: 6.1%), P = .160 with TVR as the most discriminating factor, 10.7% (SE: 4.0%) versus 29.2% (SE: 6.0%), P = .016. Our results point to RA having reason...
ESC Heart Failure, 2015
Aims Our aim is to describe the clinical characteristics and management of patients hospitalized ... more Aims Our aim is to describe the clinical characteristics and management of patients hospitalized with acute heart failure (HHF) and ambulatory patients with chronic heart failure (CHF) in Egypt and compare them with heart failure (HF) patients from other countries in the European Society of Cardiology-Heart Failure (ESC-HF) registry. Methods and results The ESC-HF Long-term Registry is a prospective, multi-centre, observational study of patients presenting to cardiology centres in member countries of the ESC. From April 2011 to February 2014, a total of 2145 patients with HF were recruited from 20 centres all over Egypt. Of these patients, 1475 (68.8%) were hospitalized with HHF, while 670 (31.2%) had CHF. Less than one-third (32.1%) of all patients were females. HHF patients {median age of 61 years [interquartile range (IQR), 53-69]} were older than CHF patients [median age of 57 years (IQR,46-64)]; P < 0.0001. They had more diabetes mellitus (45.4% vs. 31.8%; P < 0.0001). Left ventricular ejection fraction > 45% was present in 22% of HHF vs. 25.6% of CHF (P = 0.17). Atrial fibrillation existed in about a quarter of all patients (24.5%). Ischaemic heart disease was the main cause of HF in Egyptian patients. All-cause in-hospital mortality was 5%. Egyptian patients presented at a much earlier age than in other regions in the registry. They had more diabetes mellitus. Atrial fibrillation prevalence was remarkably lower. Other co-morbidities (renal dysfunction, stroke, and peripheral arterial disease) occurred less frequently. Conclusion Patients in the Egyptian cohort exhibited distinct features from HF patients in other countries in the ESC-HF Long-term Registry.
Lecture Notes in Computer Science, 2001
Cryptographic Boolean functions should have large distance to functions with simple algebraic des... more Cryptographic Boolean functions should have large distance to functions with simple algebraic description to avoid cryptanalytic attacks based on successive approximation of the round function such as the interpolation attack. Hyper-bent functions achieve the maximal minimum distance to all the coordinate functions of all bijective monomials. However, this class of functions exists only for functions with even number of inputs. In this paper we provide some constructions for Boolean functions with odd number of inputs that achieve large distance to all the coordinate functions of all bijective monomials.
The Egyptian Heart Journal, 2011
Background: The aim of this study was to investigate the effect of ivabradine on symptoms, qualit... more Background: The aim of this study was to investigate the effect of ivabradine on symptoms, quality of life, effort tolerance, and echocardiographic parameters in patients with idiopathic dilated cardiomyopathy presenting with New York Heart Association (NYHA) class III or IV heart failure (HF) symptoms. Methods: We screened 167 patients hospitalized for NYHA class III or IV chronic HF symptoms and left ventricular (LV) ejection fraction <40%. Of these, 53 were randomly assigned to either guidelines-based medical therapy alone (23 patients, control group) or ivabradine as add-on therapy (30 patients) for 3 months with about 1 year follow up. Results: After 3 months' treatment, adding ivabradine significantly reduced the heart rate from 96 to 72 bpm (p < 0.0001 versus control group), with more improvement in echocardiographic LV dimensions, LV volumes, LV ejection fraction (p = 0.045), NYHA class symptoms (p = 0.004), exercise tolerance (p = 0.03), and quality of life (p = 0.02). The average number of hospitalizations for HF over a mean longer-term follow-up of 13.5 months was 1.0 ± 1.4 in the ivabradine group versus 2.1 ± 1.1 in the control group (p = 0.003
2007 Canadian Conference on Electrical and Computer Engineering, 2007
In this paper an incremental version of line tangent space alignment (LTSA) is proposed on the ba... more In this paper an incremental version of line tangent space alignment (LTSA) is proposed on the basis of incremental locally linear embedding (LLE) generalizations and the subsequent incremental Hessian locally linear embedding (HLLE). The main goal of this algorithm is to reduce the dimensionality of high-dimension manifolds into a lower dimension representation such that the significant characteristics of the dataset
2008 Canadian Conference on Electrical and Computer Engineering, 2008
Boolean functions play a major role in the construction of symmetric key primitives such as block... more Boolean functions play a major role in the construction of symmetric key primitives such as block ciphers, stream ci-phers and hash functions. The security of these primitives depends on the cryptographic properties of the Boolean func-tions used in its construction. Various ...
2006 Canadian Conference on Electrical and Computer Engineering, 2006
In this paper, we investigate the use of Ant Colony Optimization (ACO) for automated cryptanalysi... more In this paper, we investigate the use of Ant Colony Optimization (ACO) for automated cryptanalysis of classical simple substitution ciphers. Based on our experiments, ACO-based attacks proved to be very effective on various sets of encoding keys.
2006 Canadian Conference on Electrical and Computer Engineering, 2006
Feature selection is an important research problem in different statistical learning problems inc... more Feature selection is an important research problem in different statistical learning problems including text categorization applications such as spam email classification. In designing spam filters, we often represent the email by vector space model (VSM), i.e., every email is considered as a vector of word terms. Since there are many different terms in the email, and not all classifiers can handle such a high dimension, only the most powerful discriminatory terms should be used. Another reason is that some of these features may not be influential and might carry redundant information which may confuse the classifier. Thus, feature selection, and hence dimensionality reduction, is a crucial step to get the best out of the constructed features. There are many feature selection strategies that can be applied to produce the resulting feature set. In this paper, we investigate the use of Hill Climbing, Simulated Annealing, and Threshold Accepting optimization techniques as feature selection algorithms. We also compare the performance of the above three techniques with the Linear Discriminate Analysis. Our experiment results show that all these techniques can be used not only to reduce the dimensions of the e-mail, but also improve the performance of the classification filter. Among all the strategies, simulated annealing has the best performance which reaches a classification accuracy of 95.5%.
The Indian Journal of Pediatrics, 2011
Objectives To compare T-cell function in healthy/septic preterms in relation to healthy term babi... more Objectives To compare T-cell function in healthy/septic preterms in relation to healthy term babies. Also to determine correlation of sepsis severity with T-cell function and risk to candidal infection. Methods Patients were recruited to one of three groups. Group (I) included 30 healthy growing preterms, group (II) included preterms with neonatal sepsis whereas group (III) included 30 healthy full term neonates. Patients underwent history taking and comprehensive examination plus laboratory tests including T-Lymphocyte function by blastoid transformation method using phytohaemagglutinin (PHA). Results A significant difference exists between healthy preterm vs. septic newborn T cell counts and functions especially those with multiorgan system failure. No correlation was found between candidal infection and T cell functions. Conclusions T cell functions are remarkably lower in septic newborns. Septic preterms may have low T cell functions despite absence of lymphopenia. Early detection is advised to improve outcome.
2011 seventh International Computer Engineering Conference (ICENCO'2011), 2011
In this paper, we focus on two main properties of random sequences; Hamming correlation (HC), and... more In this paper, we focus on two main properties of random sequences; Hamming correlation (HC), and linear span (LS). We study these properties for RC4 stream cipher, a family built on M-sequences, and sequences generated by Reed - Solomon Code.
Information Security Journal: A Global Perspective, 2012
Honeypots are network surveillance architectures designed to resemble easy-to-compromise computer... more Honeypots are network surveillance architectures designed to resemble easy-to-compromise computer systems. They are deployed with the aim to trap hackers in order to help security professionals capture, control, and analyze malicious Internet attacks and other activities of hackers. A botnet is an army of compromised computers controlled by a bot herder and used for illicit financial gain. Botnets have become quite popular in recent Internet attacks. Since honeypots have been deployed in many defense systems, attackers constructing and maintaining botnets are forced to find ways to avoid honeypot traps. In fact, some researchers have even suggested equipping normal machines by misleading evidence so that they appear as honeypots in order to scare away rational attackers. In this paper, we address some aspects related to the problem of honeypot detection by botmasters. In particular, we show that current honeypot architectures and operation limitations may allow attackers to systematically collect, combine and analyze evidence about the true nature of the machines they compromise. In particular, we show how a systematic technique for evidence combining such as Dempster-Shafer theory can allow botmasters to determine the true nature of compromised machines with a relatively high certainty. The obtained results demonstrate inherent limitations of current honeypot designs. We also aim to draw the attention of security professionals to work on enhancing the discussed features of honeypots in order to prevent them from being abused by botmasters.