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Dyachuk D.,University of Saskatchewan | Mazzucco M.,University of Tartu | Mazzucco M.,Software Technology and Applications Competence Center
Proceedings - IEEE/ACM International Workshop on Grid Computing | Year: 2010

With the increasing popularity of Internet-based services and applications, power efficiency is becoming a major concern for data center operators, as high electricity consumption not only increases greenhouse gas emissions, but also increases the cost of running the server farm itself. In this paper we address the problem of maximizing the revenue of a service provider by means of dynamic allocation policies that run the minimum amount of servers necessary to meet user's requirements in terms of performance. The results of several experiments executed using Wikipedia traces are described, showing that the proposed schemes work well, even if the workload is non-stationary. Since any resource allocation policy requires the use of forecasting mechanisms, various schemes allowing compensating errors in the load forecasts are presented and evaluated. © 2010 IEEE. Source


Mazzucco M.,University of Tartu | Mazzucco M.,Software Technology and Applications Competence Center | Dyachuk D.,University of Saskatchewan
Future Generation Computer Systems | Year: 2012

High electricity consumption, associated with running Internet scale server farms, not only reflects on the data center's greenhouse gas emissions, but also increases the cost of running the data center itself. In this paper, we consider the problem of maximizing the revenues of service providers running large scale data centers subject to setup cost by reducing their electricity bill, while considering the fact that clients consuming the offered services have finite non-deterministic patience. As a solution, we present and evaluate the performance of allocation policies which, in the context of both one and two-tiered systems, dynamically switch servers on and off according to changes in user demand. The algorithms we present aim at maximizing the users' experience while minimizing the amount of electricity required to run the IT infrastructure in spite of non-stationary traffic which cannot be predicted with the absolute accuracy. The results of several experiments are presented, showing that the proposed schemes perform well under different traffic conditions. © 2011 Elsevier B.V. All rights reserved. Source


Laur S.,University of Tartu | Willemson J.,Cybernetica | Willemson J.,Software Technology and Applications Competence Center | Zhang B.,Cybernetica | Zhang B.,University of Tartu
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

Most of the multi-party computation frameworks can be viewed as oblivious databases where data is stored and processed in a secret-shared form. However, data manipulation in such databases can be slow and cumbersome without dedicated protocols for certain database operations. In this paper, we provide efficient protocols for oblivious selection, filtering and shuffle - essential tools in privacy-preserving data analysis. As the first contribution, we present a 1-out-of-n oblivious transfer protocol with O(loglogn) rounds, which achieves optimal communication and time complexity and works over any ring ℤN. Secondly, we show how to construct round-efficient shuffle protocols with optimal asymptotic computation complexity and provide several optimizations. © 2011 Springer-Verlag. Source


Heiberg S.,Cybernetica | Heiberg S.,Software Technology and Applications Competence Center
Lecture Notes in Business Information Processing | Year: 2013

Estonia has implemented a specific form of electronic voting - internet voting - as a method to participate in various types of legally binding elections since 2005. The mitigation of security risks in the method has lead to changes in the voting procedures. Those changes might affect the way we think about traditional voting. © 2013 Springer-Verlag Berlin Heidelberg. Source


Willemson J.,Cybernetica | Willemson J.,Software Technology and Applications Competence Center
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

Pseudonymization is sometimes used as a light-weight alternative to fully cryptographic solutions, when information from different data sources needs to be linked in a privacy-preserving manner. In this paper, we review several previously proposed pseudonymization techniques, point out their cryptographic and design flaws. As a solution, we have developed a simple pseudonymization framework based on X-Road, a unified database access layer serving as the basis for most eGovernment services developed in Estonia. Our solution has been fully implemented and benchmarking results together with the security analysis are presented to conclude the paper. © 2011 Springer-Verlag Berlin Heidelberg. Source

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