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This article proposes an approach that accelerates the realization of user identification schemes that follow the principle of zero knowledge. The proposed approach is based on using finite field arithmetic to replace the usual modular arithmetic approaches. The application of this efficient method that was developed using Galois Fields, renders feasible an exponential reduction of the computation time required for classical zero knowledge authentication methods, such as FFSIS, Schnorr and Guillou & Quisquater. Modifications of the relevant schemes are presented that use Galois Field multiplication operations. It is shown, both theoretically and experimentally that the proposed procedure attains a per order acceleration of the execution time required for the user authentication by 2 – 3 orders of magnitude, via a hardware implementation.

User authentication procedures are a computer system's first line of defense against malicious attacks that could potentially jeopardize its availability and reliability. Computational complexity considerations may prevent system designers from implementing efficient authentication procedures. This paper presents a robust two level authentication procedure is presented that is highly efficient and suitable for multi-user systems. Authentication is attained in only a single cycle of exchanges between the user and the authentication system. Further advantages arise from the fact that with the proposed technique, it is not necessary to store lists of passwords and therefore the overhead caused in systems with large numbers of registered users is minimal. The proposed architecture is shown to be reliable while creating significant economies in the amount of information that needs to be stored. These facts therefore render the architecture highly suitable for hardware implementations.

In this paper a new approach is proposed to increase the performance of the operation of error control on data transmission. Specifically, a hardware structure for parallel Cyclic Redundancy Check (CRC) calculation is developed to speed up the error control operation of data transmission. Based on a study of the properties of both CRC and Check Sum (CS) a new error detecting scheme is developed which combines CRC and CS. Also it is shown that the proposed error detecting scheme ensures high reliability and performance of the error control operation on data transmission in comparison to CRC alone.

This paper presents modeling results for sign language videoconference traces (H.261 and H.263 encoded) which were captured from realistic multipoint IP videoconference sessions between Greek signers. By comparing traffic models against simulations, it is proven that the application of the proposed theoretical parameters into a generic continuous Markovian model can lead to a conservative, though accurate, solution for the analytical treatment of this type of traffic.

E learning is one of the revolutions that where born through the growth of the new technologies and the Internet and change everyone's way of view about education and the deliver of knowledge. It is used more and more in education as it can deliver knowledge through internet to every corner of the planet. For development e-learning systems are used various technologies and Java technology could be one of them offering unique features to these systems. Java has emerged as a powerful programming language for developing platform-independent, interactive software that can be used on the World Wide Web through a Java-enabled Web browser. This paper introduces the Java programming language, the possibilities available by using Java in asynchronous e-learning systems and an example of a self paced system that was created with Java.

As the growth of e-learning is expanding, the need for organizing and searching for e-learning content resources grows too. One can find on the internet many sites that provide searches for e-learning content resources on the web. But what about the need for the search of e-content in a e-learning platform or a digital library? SOM O.D.I.S.S.E.A.S is an intelligent searching tool using the Self-Organizing Map (SOM) algorithm, as a prototype e-content retrieval tool. The proposed searching tool has the ability to adjust and scale into any e-learning platform that requires concept-based queries. The SOM algorithm has been used successfully for document organization as well as for document retrieval. In the proposed methodology, maps are used for the automatic replacement of the unstructured, the half structured and the multidimensional data of text, in a way that similar entries in the map are represented near between them. The performance and the functionality of the document organization, and retrieval tool employing the SOM architecture, are also presented. Furthermore, experiments were performed to test the time performance of a learning algorithm used for the direct creation of teams of terms and texts enabling efficient searching and retrieval of the documents.

This paper presents a learning system (LS) which offers Greek Sign Language videos in correspondence to every text in the learning environment. The system is designed notably for deaf adults for the purpose of their lifelong vocational and educational training. In the LS, the special needs of Deaf learners are satisfied, e.g. bilingual information (text and sign language), high level of visualization, interactive and explorative leaning, and the potential of learning in peer groups via video conferencing. In this environment, for the first time, Greek signers are able to learn in their own language, the sign language. In addressing the above context, the LS is adapted to the specific learning problems of the target group, i.e. deaf adolescents and young adults. The provided content is bilingual. Bilingual experiments (spoken and signed language) in schools of the deaf and hearing impaired have shown that the use of sign language in the classroom enhance reading competence significantly. The basic objective of the present e-learning environment is the support of the equal rights of Deaf people for their access and real attendance in the vocational and educational training. The development of LS and this paper has been supported by Leonardo Da Vinci Framework Program, "DELFE" project, of European Union.