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Christos K Georgiadis

University of Macedonia
Dept. of Applied Informatics
GR-540 06 Thessaloniki
GREECE
geor@uom.gr

Journal articles

2011
E Stiakakis, C K Georgiadis (2011)  Drivers of a tourism e-business strategy : the impact of information and communication technologies   Oper Res Int J (ORIJ), Springer 11: 149-169  
Abstract: The possible interactions among tourism organizations, their customers and other organizations are considered in this article. Based on these interactions, three drivers of an integrated e-business strategy in the tourism sector are suggested: (1) customizing tourist products, personalizing services and supporting mobile services, (2) sharing tourism information and operational data, and (3) offering tailor made products and supporting user-generated content. In order to emphasize our suggestions, the most representative figures derived from recent surveys conducted by the Sectoral e-Business W@tch are selected and analyzed. These figures are: (a) the use of customer relationship management applications in tourism and the importance of mobile services for different sectors of the economy including tourism, for the first driver, (b) the use of supply chain management systems, online purchasing and finally the use of broadband Internet as a complementary indicator, for the second driver, and (c) the use of ICT-enabled product and process innovations and dynamic packaging, for the third driver. The clear positive tendencies of these figures indicate the rising importance of our suggested directions as basic drivers of a tourism e-business strategy. © 2009 Springer-Verlag.
Notes: Export Date: 27 August 2009
2010
2009
2008
C K Georgiadis, D Baltatzis, G Pangalos (2008)  Secure mobile agent environments : Modelling role assignments   International Journal of Electronic Security and Digital Forensics 1: 3. 249-267  
Abstract: This article exploits the idea of using the role-based access control model for the mobile agent authorisation problem. In our approach, when an agent migrates to a specific platform, the host assigns it a role from the local role hierarchy. The assignment is based on role decomposition that every host is eligible to perform according to a set of well-established rules. We analyse the matching procedure and we demonstrate a role management system application which is capable to compare roles and thus to assign local roles to upcoming agent roles. Moreover, we present our first efforts to model mobile agent behaviour using Coloured Petri-Nets, a powerful modelling language for systems in which communication and resource distribution play a very important role. Copyright © 2008, Inderscience Publishers.
Notes: Export Date: 27 August 2009
2006
C K Georgiadis, A Plastiras, A Manitsaris (2006)  Web services and personalized searching : Exploiting the google engine   Transactions on Computers 5: 10. 2433-2439  
Abstract: Search technology is one of the main issues which unleash the infinite prospective of the Web today. A significant aspect of this technology is its importance for achieving customer-oriented e-commerce successful activities. In this article, we will investigate the potential offered by the Google SOAP Search API to search for data on the Internet. Our approach focuses in personalizing Web search results: the resulted Web pages will take into account the interests of the individuals. Collecting and processing such information, explicitly or implicitly (e.g. from the products that are bought or the pages that are visited), may lead the user to products or services in a more accurate way. Thus, the search time is decreased and the environment becomes more user-friendly.
Notes: Export Date: 27 August 2009
2005
2003
C K Georgiadis, I K Mavridis, G I Pangalos (2003)  Healthcare teams over the Internet : Programming a certificate-based approach   International Journal of Medical Informatics 70: 2-3. 161-171  
Abstract: Healthcare environments are a representative case of collaborative environments since individuals (e.g. doctors) in many cases collaborate in order to provide care to patients in a more proficient way. At the same time modern healthcare institutions are increasingly interested in sharing access of their information resources in the networked environment. Healthcare applications over the Internet offer an attractive communication infrastructure at worldwide level but with a noticeably great factor of risk. Security has, therefore, become a major concern. However, although an adequate level of security can be relied upon digital certificates, if an appropriate security model is used, additional security considerations are needed in order to deal efficiently with the above team-work concerns. The already known Hybrid Access Control (HAC) security model supports and handles efficiently healthcare teams with active security capabilities and is capable to exploit the benefits of certificate technology. In this paper we present the way for encoding the appropriate authoritative information in various types of certificates, as well as the overall operational architecture of the implemented access control system for healthcare collaborative environments over the Internet. A pilot implementation of the proposed methodology in a major Greek hospital has shown the applicability of the proposals and the flexibility of the access control provided. © 2003 Elsevier Ireland Ltd. All rights reserved.
Notes: Cited By (since 1996): 5
2002
C K Georgiadis, I K Mavridis, G Nikolakopoulou, G I Pangalos (2002)  Implementing context and team based access control in healthcare intranets   Medical Informatics and the Internet in Medicine 27: 3. 185-201  
Abstract: The establishment of an efficient access control system in healthcare intranets is a critical security issue directly related to the protection of patients' privacy. Our C-TMAC (Context and Team-based Access Control) model is an active security access control model that layers dynamic access control concepts on top of RBAC (Role-based) and TMAC (Team-based) access control models. It also extends them in the sense that contextual information concerning collaborative activities is associated with teams of users and user permissions are dynamically filtered during runtime. These features of C-TMAC meet the specific security requirements of healthcare applications. In this paper, an experimental implementation of the C-TMAC model is described. More specifically, we present the operational architecture of the system that is used to implement C-TMAC security components in a healthcare intranet. Based on the technological platform of an Oracle Data Base Management System and Application Server, the application logic is coded with stored PL/SQL procedures that include Dynamic SQL routines for runtime value binding purposes. The resulting active security system adapts to current need-to-know requirements of users during runtime and provides fine-grained permission granularity. Apart from identity certificates for authentication, it uses attribute certificates for communicating critical security metadata, such as role membership and team participation of users.
Notes: Cited By (since 1996): 3
G Pangalos, I Mavridis, C Ilioudis, C Georgiadis (2002)  Developing a public key infrastructure for a secure regional e-health environment   Methods of Information in Medicine 41: 5. 414-418  
Abstract: Objectives: Internet technologies provide an attractive infrastructure for efficient and low cost communications in regional health information networks. The advantages provided by the Internet come however with a significantly greater element of risk to the confidentiality and integrity of information. This is because the Internet has been designed primarily to optimize information sharing and interoperability not security. The main objective of this paper is to propose the exploitation of public-key cryptography techniques to provide adequate security to enable secure healthcare Internet applications. Methods: Public-key cryptography techniques can provide the needed security infrastructure in regional health networks. In the regional health-care security framework presented in this paper, we propose the use of state-of-art Public Key Infrastructure (PKI) technology. Such an e-Health PKI consists of regional certification authorities that are implemented within the central hospitals of each region and provide their services to the rest of the healthcare establishments of the same region. Results: Significant experience in this area has been gained from the implemeatation of the PKI@AUTH project. Conclusions: The developed PKI infrastructure already successfully provides its security services to the AHEPA university hospital. The same infrastructure is designed to easily support a number of hospitals participating in a regional health information network.
Notes: Cited By (since 1996): 4
2001
I Mavridis, C Georgiadis, G Pangalos, M Khair (2001)  Access control based on attribute certificates for medical intranet applications.   Journal of medical Internet research [electronic resource] 3: 1.  
Abstract: BACKGROUND: Clinical information systems frequently use intranet and Internet technologies. However these technologies have emphasized sharing and not security, despite the sensitive and private nature of much health information. Digital certificates (electronic documents which recognize an entity or its attributes) can be used to control access in clinical intranet applications. OBJECTIVES: To outline the need for access control in distributed clinical database systems, to describe the use of digital certificates and security policies, and to propose the architecture for a system using digital certificates, cryptography and security policy to control access to clinical intranet applications. METHODS: We have previously developed a security policy, DIMEDAC (Distributed Medical Database Access Control), which is compatible with emerging public key and privilege management infrastructure. In our implementation approach we propose the use of digital certificates, to be used in conjunction with DIMEDAC. RESULTS: Our proposed access control system consists of two phases: the ways users gain their security credentials; and how these credentials are used to access medical data. Three types of digital certificates are used: identity certificates for authentication; attribute certificates for authorization; and access-rule certificates for propagation of access control policy. Once a user is identified and authenticated, subsequent access decisions are based on a combination of identity and attribute certificates, with access-rule certificates providing the policy framework. CONCLUSIONS: Access control in clinical intranet applications can be successfully and securely managed through the use of digital certificates and the DIMEDAC security policy.
Notes: Cited By (since 1996): 1

Book chapters

2003
C K Georgiadis, J Baltatzis, G I Pangalos (2003)  Programming secure mobile agents in healthcare environments using role-based permissions.   136-140 95:  
Abstract: The healthcare environment consists of vast amounts of dynamic and unstructured information, distributed over a large number of information systems. Mobile agent technology is having an ever-growing impact on the delivery of medical information. It supports acquiring and manipulating information distributed in a large number of information systems. Moreover is suitable for the computer untrained medical stuff. But the introduction of mobile agents generates advanced threads to the sensitive healthcare information, unless the proper countermeasures are taken. By applying the role-based approach to the authorization problem, we ease the sharing of information between hospital information systems and we reduce the administering part. The different initiative of the agent's migration method, results in different methods of assigning roles to the agent.
Notes:
2002
C Chousiadis, C K Georgiadis, G Pangalos (2002)  Integrating the lightweight authentication protocol (LAP) with access control mechanisms in wireless health care information systems.   697-701 90:  
Abstract: Health information networks are expected to support information exchange that is authentic, accurate, private and available when, where and to whom is needed. With the increase of the shared medical information and resources in healthcare wireless information systems, unauthorized access to the information by illegal users also increases. The security of the transmitted information is a vital issue. In this paper, we report on the development of the Lightweight Authentication Protocol (LAP), which makes a mobile and distributed system more secure and flexible and we implement it in a Health Care Environment where the clinicians use mobile and wireless devices like PDAs. We also provide an indicative example of integrating the LAP with access control mechanisms. Context-based Team Access Control (C-TMAC) model is used in this example, since it provides great flexibility on user-permissions management in collaborative healthcare environments. LAP is indeed capable to support efficiently the advanced authorization procedures of such demanding active security models.
Notes: Export Date: 27 August 2009
C K Georgiadis, I K Mavridis, G I Pangalos (2002)  Healthcare teams over the Internet : towards a certificate-based approach.   184-188 90:  
Abstract: Healthcare environments are a representative case of collaborative environments since individuals (e.g. doctors) in many cases collaborate in order to provide care to patients in a more proficient way. At the same time modem healthcare institutions are increasingly interested in sharing access of their information resources in the networked environment. Healthcare applications over the Internet offer an attractive communication infrastructure at worldwide level but with a noticeably great factor of risk. Security has therefore become a major concern for healthcare applications over the Internet. However, although an adequate level of security can be relied upon digital certificates, if an appropriate security policy is used, additional security considerations are needed in order to deal efficiently with the above team-work concerns. The already known Hybrid Access Control security model supports and handles efficiently healthcare teams with active security capabilities and is capable to exploit the benefits of certificate technology. In this paper we present the way for encoding the appropriate authoritative information in various types of certificates, as well as the overall operational architecture of the implemented access control system for healthcare collaborative environments over the Internet. A pilot implementation of the proposed methodology in a major Greek hospital has shown the applicability of the proposals and the flexibility of the access control provided.
Notes: Export Date: 27 August 2009

Conference papers

2008
E Pimenidis, C K Georgiadis (2008)  Web services for rural areas-Security challenges in development and use    
Abstract: Web services (WS) are the modern response of traders and online service providers to satisfying the increasing needs and demands of the digital communities. WS formation and operation is based on a software system designed to support interoperable machine-to-machine interaction over a network. Security is of paramount importance to WS and the ability to measure and evaluate the level of security available is key to establishing and continuing to develop the level of trust based on reputation developed by the provider of the WS. The greatest challenge in offering secure WS is to groups of people where the level of expertise of the user is low and the need for transparency of the service provision quite high, such as the case with services offered primarily to people in rural areas. Providers of such services face many challenges in balancing the requirements for performance, interoperability, and security against the cost of implementing secure systems and running profitable operations through low income generating WS. A review of services offered, of the users and the challenges in building online trust among providers and users are discussed for the case of rural areas in the United Kingdom. © 2009 Elsevier B.V. All rights reserved.
Notes: Export Date: 27 August 2009
C K Georgiadis, S H Stergiopoulou (2008)  Mobile commerce application development : Implementing personalized services   In: Proceedings - 7th International Conference on Mobile Business, ICMB 2008, Creativity and Convergence 201-210  
Abstract: M-commerce applications allow users instant access to business-critical communication and information. Personalization technology delivers a new dimension to mobile businesses. Its level of detail and accuracy opens up a broad scope of potential applications, enabling them to tailor their services to the exact interests and expectations of mobile users. We indicate the advantages of a flexible m-commerce application, capable of providing context-specific information to users according their profile and specialty. Our demonstrative .NET application case study illustrates an example of how enterprises can be organised to make use of new technology. The goal is to provide up to date necessary information to their employees (such as delivery drivers and representatives), so as to facilitate their tasks and to obviate potential problems and delays. © 2008 IEEE.
Notes: Conference code: 73501
T L Theodorou, G E Violettas, C K Georgiadis (2008)  Wiki-Dic : Implementing an e-voting application to support user-generated content   In: MCCSIS'08 - IADIS Multi Conference on Computer Science and Information Systems; Proceedings e-Commerce 2008 209-214  
Abstract: E-voting is an election system that allows a voter to record his or her secure and secret ballot electronically. We can also define as e-voting the process of evaluating an article or ranking a translation of a specific scientific term in a relevant web site. This all process of participation and interaction is one of the Web 2.0 definitions, the collaborative knowledge. An electronic (on-line) dictionary in order to succeed has to consider this factor. It has to be interactive and it has to attract and support the users' participation and contribution. Therefore, an e-voting system may confront properly these issues. In the e-dictionary we propose here ("Wiki- Dic"), some experts begin a dictionary, they start filling it with words and translations, and all users are allowed not only to look for the translation, but also to vote for it. The most voted translations go to the top. Every minute the users may be informed for the most voted translation, as the most widely accepted definition appears first in the row. © 2008 IADIS.
Notes: Conference code: 74998
2007
C Ilioudis, D Baltatzis, G Pangalos, C Georgiadis (2007)  Securing healthgrid environments   In: SECRYPT 2007 - International Conference on Security and Cryptography, Proceedings 394-401  
Abstract: Grid technologies promise to change the way that health organizations tackle complex problems by offering unprecedented opportunities for resource sharing and collaboration. Healthgrids are Grid infrastructures comprising applications, services or middleware components that deal with the specific problems arising in the processing of biomedical data. Resources in Healthgrids are databases, computing power, medical expertise and even medical devices. Securing this new environment in Health organizations is a major issue today. Security considerations and more specifically authorization decisions is a critical problem. Personal data is confidential, so access to the information must be restricted to authorized and authenticated persons. Furthermore data must be protected to guarantee its confidentiality and integrity. This work provides a suitable authorization mechanism that facilitates the usage of grid and agent technology in HealthGrid environments. More specifically, our approach applies the RBAC access control model for dynamically assigning security roles to visiting agents on hosts of the HealthGrid environment. Our methodology proposes a flexible role decomposition method, which facilitates the role assignment process. The role decomposition relies on a set of common Attribute Fields, shared between Grid's hosts, filled with Attribute values that every host evaluates according to its security goals. In any case, every host participating in the grid retains its security policy without altering or compromising its security policy in order to participate in the agent exchange process. The proposed process and the related assignment algorithms have been experimentally implemented and applied in a typical health environment. The results have shown that the proposed framework is applicable and implementable, and can be applied successfully in real life health care environments.
Notes: Conference code: 76455
C K Georgiadis, G Melas, P Tzamtis (2007)  Location based services for mobile commerce applications   In: ICE-B 2007 - Proceedings of the 2nd International Conference on e-Business 162-167  
Abstract: Mobile setting considerations provide valuable issues regarding flexible mobile applications. In this paper, we indicate the advantages of an m-commerce application capable to provide users with useful information (e.g. historical buildings, shops, hotels) according to their location. First, the application creates a basic profile of the current user (type of information the user is mainly interested in). Then, in addition with the location awareness of the user's position the application provides only useful information according to the user's whereabouts. When the user is alerted that he is in close proximity of one place that he is interested in, he has the option to access more info about it (streaming video or photo and text). The application is implemented using the Java Micro Edition (Java ME) platform and is mainly making use of the Location API, which provides information about the device's present physical location and orientation. The customized information is stored online and is accessed only when user needs it.
Notes: Conference code: 75484
2005
D Baltatzis, C K Georgiadis, G Pangalos (2005)  A flexible authorization mechanism for Virtual Organizations   In: Proceedings - International Carnahan Conference on Security Technology  
Abstract: Authorization decisions are a critical security concern in today's distributed large information systems. These authorizations are significantly different from those in centralized or smaller systems. Mobile agent technology on the other hand provides a useful tool to explore and facilitate information sharing in distributed systems. However, agents are often restricted by the security problems related to the large scale distributed systems and the multi-user operating system environments within they usually operate. This article provides a suitable framework for authorizing mobile agents where an out sized and dynamic set of principals forming a virtual organization (VO), with mutual mistrust between them, has to rely on pieces of application code which autonomously migrate and execute on consecutive hosts. The role based access control model (RBAC) is used for dynamically assigning security roles to visiting agents on each hosting platform. The proposed methodology is particularly suitable for handling authorizations in VOs. ©2005 IEEE.
Notes: Conference code: 69228
D A Baltatzis, C K Georgiadis, I G Pagkalos (2005)  Mobile agents in E-commerce environments : Supporting collaborative activities   In: Proceedings - International Conference on Computational Intelligence for Modelling, Control and Automation, CIMCA 2005 and International Conference on Intelligent Agents, Web Technologies and Internet 205-210  
Abstract: E-commerce operations are frequently repetitive with a large segment suitable to computer aids and automation. Moreover, managing e-commerce collaborative activities on the Web requires knowing exactly what information to share with whom. Mobile agents become relevant candidates to assist users as it is largely accepted that have the ability to address efficiently some of these problems. However, mobile agent technology carries with it associated security vulnerabilities that had to be addressed in order to be functional. A key requirement is to find a flexible, convenient and effective method to work out the mobile agent authorization problem. We argue that a satisfactory approach for this problem is to dynamically map casual users, like mobile agents, with predefined organizational security roles, based on a flexible role-assignment mechanism. © 2005 IEEE.
Notes: Conference code: 69201
2001
C K Georgiadis, I Mavridis, G Pangalos, R K Thomas (2001)  Flexible team-based access control using contexts   In: Proceedings of Sixth ACM Symposium on Access Control Models and Technologies (SACMAT 2001) 21-27  
Abstract: We discuss the integration of contextual information with team-based access control. The TMAC model was formulated by Thomas in [1] to provide access control for collaborative activity best accomplished by teams of users. In TMAC, access control revolves around teams, where a "team" is an abstraction that encapsulates a collection of users in specific roles and collaborating with the objective of accomplishing a specific task or goal. Users who belong to a team are given access to resources used by a team. However, the effective permissions of a user are always derived from permission types defined for roles that the user belongs to. TMAC is an example of what we call "active security models". These models are aware of the context associated with an ongoing activity in providing access control and thus distinguish the passive concept of permission assignment from the active concept of context-based permission activation. The ability to integrate contextual information allows models such as TMAC to be flexible and express a variety of access policies that can provide tight and just-in-time permission activation.
Notes: Conference code: 60498
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