Bounded memory Dolev-Yao adversaries in collaborative systems
In a collaborative system, the agents collaborate to achieve a common goal, but they are not willing to share some sensitive private information.
The question is how much damage can be done by a malicious participant sitting inside the system.
We assume that all the participants (including internal adversaries) have bounded memory – at any moment, they can store only a fixed number of messages of a fixed size. The Dolev–Yao adversaries can compose, decompose, eavesdrop, and intercept messages, and create fresh values (nonces), but within their bounded memory.
We prove that the secrecy problem is PSPACE-complete in the bounded memory model where all actions are balanced and a potentially infinite number of the nonce updates is allowed.
We also show that the well-known security protocol anomalies (starting from the Lowe attack to the Needham–Schroeder protocol) can be rephrased within the bounded memory paradigm with the explicit memory bounds.
The direction of cloud computing protection development is considered in the article. It is suggested to consider the structure of a queuing system based on processing data centers (PDC), as the combination of six components: the hardware PDC element; telecommunication PDC resources access element; users and the software associated to them; the «middle» PDC layer, providing calculating virtualization and including control system; application services, provided by PDC as the layer of application software for guest operating systems; data storage systems, especially databases. The ways of data protection in every subsystem, the directions of necessary development and the possibility of different security levels provision are discussed in the article. According to the author, the most complicated objective is to certify access control system in modern database systems like Oracle and DB-2.
An indirect measurement technique for temperature fields of car tires and temperatures of brakes is discussed. The technique is based on a mathematical model of tire heating. Model parameter identification methods, simulation and experimental results and included.
In this paper the authors propose a new approach to teaching practical information security in higher school based on case studies. They justify its place in information security curriculum by providing an example from the experience of using the approach for BSc and MSc students of Higher School of Economics in the courses on «Technical and Organizational Aspects of Information Security and Information Security Technologies». This paper fills the gap in existing practices for teaching information security which currently lack in guidelines for designing case studies and integrating them into the curriculum.
Recent work on structure-preserving signatures studies optimality of these schemes in terms of the number of group elements needed in the verification key and the signature, and the number of pairing-product equations in the verification algorithm. While the size of keys and signatures is crucial for many applications, another important aspect to consider for performance is the time it takes to verify a given signature. By far, the most expensive operation during verification is the computation of pairings. However, the concrete number of pairings that one needs to compute is not captured by the number of pairing-product equations considered in earlier work. To fill this gap, we consider the question of what is the minimal number of pairings that one needs to compute in the verification of structure-preserving signatures. First, we prove lower bounds for schemes in the Type II setting that are secure under chosen message attacks in the generic group model, and we show that three pairings are necessary and that at most one of these pairings can be precomputed. We also extend our lower bound proof to schemes secure under random message attacks and show that in this case two pairings are still necessary. Second, we build an automated tool to search for schemes matching our lower bounds. The tool can generate automatically and exhaustively all valid structure-preserving signatures within a user-specified search space, and analyze their (bounded) security in the generic group model. Interestingly, using this tool, we find a new randomizable structure-preserving signature scheme in the Type II setting that is optimal with respect to the lower bound on the number of pairings, and also minimal with respect to the number of group operations that have to be computed during verification.
We consider certain spaces of functions on the circle, which naturally appear in harmonic analysis, and superposition operators on these spaces. We study the following question: which functions have the property that each their superposition with a homeomorphism of the circle belongs to a given space? We also study the multidimensional case.
We consider the spaces of functions on the m-dimensional torus, whose Fourier transform is p -summable. We obtain estimates for the norms of the exponential functions deformed by a C1 -smooth phase. The results generalize to the multidimensional case the one-dimensional results obtained by the author earlier in “Quantitative estimates in the Beurling—Helson theorem”, Sbornik: Mathematics, 201:12 (2010), 1811 – 1836.
We consider the spaces of function on the circle whose Fourier transform is p-summable. We obtain estimates for the norms of exponential functions deformed by a C1 -smooth phase.
This proceedings publication is a compilation of selected contributions from the “Third International Conference on the Dynamics of Information Systems” which took place at the University of Florida, Gainesville, February 16–18, 2011. The purpose of this conference was to bring together scientists and engineers from industry, government, and academia in order to exchange new discoveries and results in a broad range of topics relevant to the theory and practice of dynamics of information systems. Dynamics of Information Systems: Mathematical Foundation presents state-of-the art research and is intended for graduate students and researchers interested in some of the most recent discoveries in information theory and dynamical systems. Scientists in other disciplines may also benefit from the applications of new developments to their own area of study.