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    Context-aware Security Models for PaaS-enabled Access Control
    ( 2016-04) Veloudis, Simeon ; Verginadis, Yannis ; Pationiotakis, Ioannis ; Paraskakis, Iraklis ; Mentzas, Grigoris
    Enterprises are embracing cloud computing in order to reduce costs and increase agility in their everyday business operations. Nevertheless, due mainly to confidentiality, privacy and integrity concerns, many are still reluctant to migrate their sensitive data to the cloud. In this paper, firstly, we outline the construction of a suitable Context-aware Security Model, for enhancing security in cloud applications. Secondly, we outline the construction of an extensible and declarative formalism for representing policy-related knowledge, one which disentangles the definition of a policy from the code employed for enforcing it. Both of them will be employed for supporting innovative PaaS-enabled access control mechanisms.
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    Teaching, Learning and Assessment of Agents and Robotics in a Computer Science Curriculum
    (Springer International Publishing, 2017) Ioanna Stamatopoulou ; Konstantinos Dimopoulos ; Petros Kefalas
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    Ontological Definition of Governance Framework for Security Policies in Cloud Environments
    ( 2017-09) Veloudis, Simeon ; Paraskakis, I. ; Petsos, Christos
    The cloud computing paradigm enables enterprises to realise sig- nificant cost savings whilst boosting their agility and productivity. However, security and privacy concerns generally deter enterprises from migrating their critical data to the cloud. One way to alleviate these concerns, hence bolster the adoption of cloud computing, is to devise adequate security policies that control the manner in which these data are stored and accessed in the cloud. Nevertheless, for enterprises to entrust these policies, a framework capable of providing assurances about their correctness is required. This work proposes such a framework. In particular, it proposes an approach that enables enterprises to define their own view of what consti- tutes a correct policy through the formulation of an appropriate set of well-formedness constraints. These constraints are expressed ontologically thus enabling—by virtue of semantic inferencing— automated reasoning about their satisfaction by the policies
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    Ontological Framework for Ensuring Correctness of Security Policies in Cloud Environments
    ( 2017-09) Veloudis, Simeon ; Paraskakis, I. ; Petsos, Christos
    By embracing the cloud computing paradigm enterprises are able to boost their agility and productivity whilst realising significant cost savings. However, many enterprises are reluctant to adopt cloud services for supporting their critical operations due to security and privacy concerns. One way to alleviate these concerns is to devise policies that infuse suitable security controls in cloud services. This work proposes a class of ontologically-expressed rules, namely the so-called axiomatic rules, that aim at ensuring the correctness of these policies by harnessing the various knowledge artefacts that they embody. It also articulates an adequate framework for the expression of policies, one which provides ontological templates for modelling the knowledge artefacts encoded in the policies and which form the basis for the proposed axiomatic rules.
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    An Ontological Template for Context Expressions in Attribute-Based Access Control Policies
    ( 2017-04) Veloudis, Simeon ; Paraskakis, I. ; Petsos, Christos ; Verginadis, Yannis ; Pationiotakis, Ioannis ; Mentzas, Grigoris
    By taking up the cloud computing paradigm enterprises are able to realise significant cost savings whilst increasing their agility and productivity. However, due to security concerns, many enterprises are reluctant to migrate their critical data and operations to the cloud. One way to alleviate these concerns is to devise suitable policies that infuse adequate access controls into cloud services. However, the dynamicity inherent in cloud environments, coupled with the heterogeneous nature of cloud services, hinders the formulation of effective and interoperable access control policies that are suitable for the underlying domain of application. To this end, this work proposes an ontological template for the semantic representation of context expressions in access control policies. This template is underpinned by a suitable set of interrelated concepts that generically capture a wide range of contextual knowledge that must be considered during the evaluation of policies.