George Violaris
Publications
The following are my peer reviewed research publications.
Engaging mobility with file sharing is considered very promising in today’s run Anywhere, Anytime, Anything (3As) environments. The Bittorrent file sharing protocol can be rarely combined with the mobility scenario framework since resources are not available due to the dynamically changing topology network. As a result, mobility in P2P-oriented file sharing platforms, degrades the end-to-end efficiency and the system’s performance. This work proposes a new hybridized model, which takes into account the mobility characteristics of the combined Bittorrent protocol in a centralized manner enabling partial mobility characteristics, where the clients of the network use a distinct technique to differentiate between mobile and static nodes. Many parameters were taken into consideration like the round trip delays, the diffusion process, and the seeding techniques, targeting the maximization of the average throughput in the clustered swarms containing mobile peers. Partial mobility characteristics are set in a peer-tracker and peer-peer communication enhancement schema with partial mobility, allowing an optimistic approach to attain high availability and throughput response as simulation results show.
Peer-to-Peer computing is nowadays the application platform which utilizes a novel distributed computing paradigm. It allows any number of participants to exchange and coordinate their resources with minimum overhead through centralized servers/services. This paradigm is also gaining ground in mobile computing environments. By merging the wireless and the static worlds of Peer-to-Peer applications, new services emerge. As Peer-to-Peer networks have nowadays become the basis for efficiently sharing data among users (both wireless and static) this work elaborates on the design of a new simulation framework via which, a mobility-based scenario can be utilized using the Bittorrent protocol. The framework uses a structured-based overlay for the static peers, and unstructured for mobile peers. Many parameters were introduced for the diffusion process and the seeding techniques that are utilized by the Bittorrent simulation framework. By using the Object Oriented design paradigm the proposed simulation framework is developed to be highly scalable being capable to potentially host new components. The simulation tool can encompass a scenario with partial mobility characteristics in a Peer-tracker and a Peer-to-Peer communication enhancement scheme. The proposed simulation framework can evaluate effectively the scalable mobility and can estimate the availability of requested resources of each individual user (both mobile and static). Finally the created simulation framework and the designed modules take into consideration the active intercluster peer participation and evaluate a degree of participation while resources are being exchanged.
Successful out-of-band authentication in popular languages such as PHP has proven to be problematic and in many ways unsafe as dynamically typed languages allow for more than one ways of doing things, and the standards set out are usually not followed. It is true that out-of-band authentication using SMS messaging enhances the security of simple passwords specified by users, however many times the handling of the One-Time-Passwords (OTP) on the server side is done with disregard of the ways an attacker can bypass the requirement for such a feature. It is therefore essential to find ways which the OTP cannot be brute-forced or circumvented, by providing mechanisms such as automatic purging of OTPs from the database and enhancing the safety of the server traffic handling as well as the HTTP form submission requests and responses with a library known as Hash cash. By using this method, a potential attacker would be met by a time-consuming challenge, which would leave any sort of brute-force, denial of service or requirement circumvention attacks impractical for gaining access to a PHP login system. Furthermore, the usage of Hash cash for credential retransmission and re-authentication for vital aspects of the user’s workflow while authenticated, make such as system much more impenetrable than using simple out-of-band or other two-factor authentication schemes.