ABSTRACT IEEE 802.11e is the indisputable standard for supporting multimedia traffic in modern Wi... more ABSTRACT IEEE 802.11e is the indisputable standard for supporting multimedia traffic in modern Wireless Local Area Networks. However, it has been proven incapable of handling efficiently multimedia flows in congested networks. The main reason for this suboptimal behavior roots from the static nature of resource allocation specified in IEEE 802.11e. Dynamic tuning of the MAC parameters has demonstrated a beneficial performance in terms of application efficiency. Nevertheless, it is of great importance that this adaptation takes place by considering the multimedia traffic characteristics. In this paper, a cross-layer MAC-centric mechanism is introduced, under the name X-EDCA. The mechanism is designed to cope with high load situations in IEEE 802.11e wireless infrastructure networks by selectively prioritizing and protecting sensitive multimedia frames. The proposed scheme is evaluated and its effectiveness is proven by means of simulation.
The security related characteristics of entities, the contextual information that describes them ... more The security related characteristics of entities, the contextual information that describes them and the previous or concurrent usages exercised in the system are the criteria that the Usage CONtrol (UCON) family of models utilizes in the usage decision process. In this paper, a detailed classication of the aforementioned criteria along with a representative usage scenario for each category is presented, unveiling a number of UCON's limitations. In turn, a Use-based Usage CONtrol (UseCON) model is proposed that provides, for the creation of a usage decision, enhanced handling of information regarding context and previ- ous or current usages exercised in the system. The enhanced capabilities of the proposed approach are demonstrated and discussed with the use of detailed application examples.
The operational characteristics of ubiquitous computing environments (UbiCom) generate new access... more The operational characteristics of ubiquitous computing environments (UbiCom) generate new access control requirements which existing classical access control models fail to support efficiently. However, the Usage Control (UCON) family of models introduces components and mechanisms that seem to be able to partially match the specific requirements imposed by UbiCom environments. In this paper, an evaluation of current access control models based on a brief study of UbiCom access control requirements is presented. Then, a new access control approach that extends UCON towards a differentiated utilization of attribute mutability for easiness of administration, better performance and lower operational cost in UbiCom environments is proposed.
Usage CONtrol (UCON) is a next generation access control model enhanced with capabilities present... more Usage CONtrol (UCON) is a next generation access control model enhanced with capabilities presented in trust and digital rights management. However, modern computing environments are usually introducing complex usage scenarios. Such a complexity results in involving a large number of entities and in utilizing multi party contextual information during the decision making process of a particular usage. Moreover, usage control is demanded to support novel access modes on single or composite resources, while taking into account new socio-technical abstractions and relations. In this paper, a number of challenging issues faced when UCON is applied in modern computing environments are highlighted through the utilization of representative usage scenarios. The results of this study are revealing various limitations in contextual information handling, lack to support complicated usage modes of subjects on objects, and weaknesses in utilizing information concerning previous or current usages of system resources.
International Journal On Advances In Intelligent Systems, Sep 2011
Although Classical Test Theory has been used by the measurement community for almost a century, I... more Although Classical Test Theory has been used by the measurement community for almost a century, Item Response Theory has become commonplace for educational assessment development, evaluation and refinement in recent decades. Its potential for improving test items as well as eliminating the ambiguous or misleading ones is substantial. However, in order to estimate its parameters and produce reliable results, IRT requires a large sample size of examinees, thus limiting its use to large-scale testing programs. Nevertheless, the accuracy of parameter estimates becomes of lesser importance when trying to detect items whose parameters exceed a threshold value. Under this consideration, the present study investigates the application of IRT-based assessment evaluation to small sample sizes through a series of simulations. Additionally, it introduces a set of quality indices, whih exhibit the success rate of identifying potentially flawed items in a way that test developers without a significant statistical background can easily comprehend and utilize.
The emergence of grid and cloud computing systems has introduced new security concepts, so it req... more The emergence of grid and cloud computing systems has introduced new security concepts, so it requires new access control approaches. Traditional systems engineering processes can be enriched with helper approaches that can facilitate the definition of access control requirements in such complex environments. Looking towards a holistic approach on the definition of access control requirements, we propose a four-layer conceptual categorization. In addition, an example is given so that to demonstrate the utilization of the proposed categorization in a grid scenario for defining access control requirements, and evaluate their fulfilment vis-à-vis contemporary employed access control approaches.
AbstractThis paper presents a study which investigates user behavior towards electronic banking ... more AbstractThis paper presents a study which investigates user behavior towards electronic banking (e-banking) and particularly in internet banking based on behavioral theoretical models and scales such as the theory of planned behavior (TPB), the diffusion of innovations theory, ...
ABSTRACT Grooming attack recognition is a complex issue that is difficult to address using simple... more ABSTRACT Grooming attack recognition is a complex issue that is difficult to address using simple word matching in order to identify potential hazard for minor users. In this paper, the utilization of document classification to create patterns from real dialogs is proposed. Furthermore, a decision making method that results in generating proper warning signals based on the classification results is introduced. The decision making method is then applied using the best ranked algorithm with a comparative evaluation which conducted on seven document classification algorithms.
This paper presents a survey on social networks' privacy leaks and the potential hazards for user... more This paper presents a survey on social networks' privacy leaks and the potential hazards for users, especially teenagers. In particular, the profiles of two teenagers, one male and one female, with fake names were created. Using a suitable software tool, friend requests were sent massively. As a result, two networks of friends were created and access was granted to a significant amount of users' personal information. Both profiles received requests for friendship and personal chat by adults aged up to 53 years old. In general the survey leads to results that reveal several hazards for children and critical issues about privacy of social network users.
The administration of authorizations in modern Web-based computing environments has become a prim... more The administration of authorizations in modern Web-based computing environments has become a primary concern. Application security is characterized by a significant complexity, due to the large number of variations and combinations of objects and operations to be protected. Thus, there is a need for data, processes and context parameters, like time and location, to be combined into a security model that ensures correct decision-making for access. Moreover, access control must often be based on dynamic functional requirements that are capable of embedding the required context information to express application-level access control policies in new application domains, as for example Internet workflow applications. In this work a new paradigm of dynamic and decentralized administration of access control that is based on the DARBAC model is presented. DARBAC concerns access control for a wide-range of collaborative applications and aims to provide fine-grained and dynamic administration of authorizations. The presented implementation assumes Web-based applications to support enforcing of access control at a distributed platform level, and it demonstrates in a step-by-step basis the construction of DARBAC components and their management during run-time.
Abstract Role-based mechanisms usually provide a sufficient way to establish access control in mo... more Abstract Role-based mechanisms usually provide a sufficient way to establish access control in most information systems. Passive security permission assignment cannot however support efficiently the dynamic aspects of many modern information systems. Health Care information systems provide a good example of such an environment. In dynamically changing clinical workflow environments there is a need for active security permission activation. In order to address this problem we propose to utilize the concept of ...
ABSTRACT IEEE 802.11e is the indisputable standard for supporting multimedia traffic in modern Wi... more ABSTRACT IEEE 802.11e is the indisputable standard for supporting multimedia traffic in modern Wireless Local Area Networks. However, it has been proven incapable of handling efficiently multimedia flows in congested networks. The main reason for this suboptimal behavior roots from the static nature of resource allocation specified in IEEE 802.11e. Dynamic tuning of the MAC parameters has demonstrated a beneficial performance in terms of application efficiency. Nevertheless, it is of great importance that this adaptation takes place by considering the multimedia traffic characteristics. In this paper, a cross-layer MAC-centric mechanism is introduced, under the name X-EDCA. The mechanism is designed to cope with high load situations in IEEE 802.11e wireless infrastructure networks by selectively prioritizing and protecting sensitive multimedia frames. The proposed scheme is evaluated and its effectiveness is proven by means of simulation.
The security related characteristics of entities, the contextual information that describes them ... more The security related characteristics of entities, the contextual information that describes them and the previous or concurrent usages exercised in the system are the criteria that the Usage CONtrol (UCON) family of models utilizes in the usage decision process. In this paper, a detailed classication of the aforementioned criteria along with a representative usage scenario for each category is presented, unveiling a number of UCON's limitations. In turn, a Use-based Usage CONtrol (UseCON) model is proposed that provides, for the creation of a usage decision, enhanced handling of information regarding context and previ- ous or current usages exercised in the system. The enhanced capabilities of the proposed approach are demonstrated and discussed with the use of detailed application examples.
The operational characteristics of ubiquitous computing environments (UbiCom) generate new access... more The operational characteristics of ubiquitous computing environments (UbiCom) generate new access control requirements which existing classical access control models fail to support efficiently. However, the Usage Control (UCON) family of models introduces components and mechanisms that seem to be able to partially match the specific requirements imposed by UbiCom environments. In this paper, an evaluation of current access control models based on a brief study of UbiCom access control requirements is presented. Then, a new access control approach that extends UCON towards a differentiated utilization of attribute mutability for easiness of administration, better performance and lower operational cost in UbiCom environments is proposed.
Usage CONtrol (UCON) is a next generation access control model enhanced with capabilities present... more Usage CONtrol (UCON) is a next generation access control model enhanced with capabilities presented in trust and digital rights management. However, modern computing environments are usually introducing complex usage scenarios. Such a complexity results in involving a large number of entities and in utilizing multi party contextual information during the decision making process of a particular usage. Moreover, usage control is demanded to support novel access modes on single or composite resources, while taking into account new socio-technical abstractions and relations. In this paper, a number of challenging issues faced when UCON is applied in modern computing environments are highlighted through the utilization of representative usage scenarios. The results of this study are revealing various limitations in contextual information handling, lack to support complicated usage modes of subjects on objects, and weaknesses in utilizing information concerning previous or current usages of system resources.
International Journal On Advances In Intelligent Systems, Sep 2011
Although Classical Test Theory has been used by the measurement community for almost a century, I... more Although Classical Test Theory has been used by the measurement community for almost a century, Item Response Theory has become commonplace for educational assessment development, evaluation and refinement in recent decades. Its potential for improving test items as well as eliminating the ambiguous or misleading ones is substantial. However, in order to estimate its parameters and produce reliable results, IRT requires a large sample size of examinees, thus limiting its use to large-scale testing programs. Nevertheless, the accuracy of parameter estimates becomes of lesser importance when trying to detect items whose parameters exceed a threshold value. Under this consideration, the present study investigates the application of IRT-based assessment evaluation to small sample sizes through a series of simulations. Additionally, it introduces a set of quality indices, whih exhibit the success rate of identifying potentially flawed items in a way that test developers without a significant statistical background can easily comprehend and utilize.
The emergence of grid and cloud computing systems has introduced new security concepts, so it req... more The emergence of grid and cloud computing systems has introduced new security concepts, so it requires new access control approaches. Traditional systems engineering processes can be enriched with helper approaches that can facilitate the definition of access control requirements in such complex environments. Looking towards a holistic approach on the definition of access control requirements, we propose a four-layer conceptual categorization. In addition, an example is given so that to demonstrate the utilization of the proposed categorization in a grid scenario for defining access control requirements, and evaluate their fulfilment vis-à-vis contemporary employed access control approaches.
AbstractThis paper presents a study which investigates user behavior towards electronic banking ... more AbstractThis paper presents a study which investigates user behavior towards electronic banking (e-banking) and particularly in internet banking based on behavioral theoretical models and scales such as the theory of planned behavior (TPB), the diffusion of innovations theory, ...
ABSTRACT Grooming attack recognition is a complex issue that is difficult to address using simple... more ABSTRACT Grooming attack recognition is a complex issue that is difficult to address using simple word matching in order to identify potential hazard for minor users. In this paper, the utilization of document classification to create patterns from real dialogs is proposed. Furthermore, a decision making method that results in generating proper warning signals based on the classification results is introduced. The decision making method is then applied using the best ranked algorithm with a comparative evaluation which conducted on seven document classification algorithms.
This paper presents a survey on social networks' privacy leaks and the potential hazards for user... more This paper presents a survey on social networks' privacy leaks and the potential hazards for users, especially teenagers. In particular, the profiles of two teenagers, one male and one female, with fake names were created. Using a suitable software tool, friend requests were sent massively. As a result, two networks of friends were created and access was granted to a significant amount of users' personal information. Both profiles received requests for friendship and personal chat by adults aged up to 53 years old. In general the survey leads to results that reveal several hazards for children and critical issues about privacy of social network users.
The administration of authorizations in modern Web-based computing environments has become a prim... more The administration of authorizations in modern Web-based computing environments has become a primary concern. Application security is characterized by a significant complexity, due to the large number of variations and combinations of objects and operations to be protected. Thus, there is a need for data, processes and context parameters, like time and location, to be combined into a security model that ensures correct decision-making for access. Moreover, access control must often be based on dynamic functional requirements that are capable of embedding the required context information to express application-level access control policies in new application domains, as for example Internet workflow applications. In this work a new paradigm of dynamic and decentralized administration of access control that is based on the DARBAC model is presented. DARBAC concerns access control for a wide-range of collaborative applications and aims to provide fine-grained and dynamic administration of authorizations. The presented implementation assumes Web-based applications to support enforcing of access control at a distributed platform level, and it demonstrates in a step-by-step basis the construction of DARBAC components and their management during run-time.
Abstract Role-based mechanisms usually provide a sufficient way to establish access control in mo... more Abstract Role-based mechanisms usually provide a sufficient way to establish access control in most information systems. Passive security permission assignment cannot however support efficiently the dynamic aspects of many modern information systems. Health Care information systems provide a good example of such an environment. In dynamically changing clinical workflow environments there is a need for active security permission activation. In order to address this problem we propose to utilize the concept of ...
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