In this paper we propose cryptosystems based on subgroup distortion in hyperbolic groups. We also include concrete examples of hyperbolic groups as possible platforms.
We address one of the main open issues about the use of diversity in multiple classifier systems: the effectiveness of the explicit use of diversity measures for creation of classifier ensembles. So far, diversity measures have been mostly used for ensemble pruning, namely, for selecting a subset of classifiers out of an original, larger ensemble. Here we focus on pruning techniques based on forward/backward selection, since they allow a direct comparison with the simple estimation of accuracy of classifier ensemble. We empirically carry out this comparison for several diversity measures and benchmark data sets, using bagging as the ensemble construction technique, and majority voting as the fusion rule. Our results provide further and more direct evidence to previous observations against the effectiveness of the use of diversity measures for ensemble pruning, but also show that, combined with ensemble accuracy estimated on a validation set, diversity can have a regularization effect when the validation set size is small.
A class of xorshift random number generators (RNGs) are introduced by Marsaglia. We have proposed an algorithm which constructs a full period xorshift RNG from a given primitive polynomial. It is shown there is a weakness present in those RNGs and is suggested its improvement. A separate algorithm is also proposed which returns a full period xorshift generator with desired number of xorshift operations.%We also introduce the notion of tweaked primitive multiple-recursive matrix method with improved linear complexity.
The advent of language implementation tools such as PyPy and Truffle/Graal have reinvigorated and broadened interest in topics related to automatic compiler generation and optimization.Given this broader interest, we revisit the Futamura Projections using a novel diagram scheme.Through these diagrams we emphasize the recurring patterns in the Futamura Projections while addressing their complexity and abstract nature.We anticipate that this approach will improve the accessibility of the Futamura Projections and help foster analysis of those new tools through the lens of partial evaluation.
In this paper, we describe secure gateway for Internet of Things (IoT) devices with internal AAA mechanism, implemented to connect IoT sensors with Internet users. Secure gateway described in this paper allows to (1) authenticate each connected device, (2) authorise connection or reconfiguration performed by the device and (3) account each action. The same applies to Internet users who want to connect, download data from or upload data to an IoT device. Secure Gateway with internal AAA mechanism could be used in Smart Cities environments and in other IoT deployments where security is a critical concern. The mechanism presented in this paper is a new concept and has been practically validated in Polish national research network PL-LAB2020.
The availability of cheap and widely applicable person identification techniques is essential due to wide-spread usage of online services. The dynamics of typing is characteristic to particular users, and users are hardly able to mimic the dynamics of typing of others. State-of-the-art solutions for person identification from the dynamics of typing are based on machine learning. The presence of hubs, i.e., few instances that appear as nearest neighbors of surprisingly many other instances, have been observed in various domains recently and hubness-aware machine learning approaches have been shown to work well in those domains. However, hubness has not been studied in context of person identification yet, and hubness-aware techniques have not been applied for this task. In this paper, we examine hubness in typing data and propose to use EC$k$NN, a recent hubness-aware regression techniques together with dynamic time warping for person identification. We collected time-series data describing the dynamics of typing and used it to evaluate our approach. Experimental results show that hubness-aware techniques outperform state-of-the-art time-series classifiers.
SQL Injection is one of the vulnerabilities in OWASPs Top Ten List for Web Based Application Exploitation.These types of attacks takes place on Dynamic Web applications as they interact with the databases for the various operations.Current Content Management System like Drupal, Joomla or Wordpress have all the information stored in their databases. A single intrusion into these types of websites can lead to overall control of websites by the attacker. Researchers are aware of the basic SQL Injection attacks but there are numerous SQL Injection attacks which are yet to be Prevented and Detected. Over here, we present the extensive review for the Advanced SQL Injection attack such as Fast Flux Sql Injection, Compounded SQL Injection and Deep Blind SQL Injection. We also analyze the detection and prevention using the classical methods as well as modern approaches. We will be discussing the Comparative Evaluation for prevention of SQL Injection.
The paper concerns a risk assessment and management methodology in critical infrastructures. The aim of the paper is to present researches on risk management within the experimentation tool based on the OSCAD software. The researches are focused on interdependent infrastructures where the specific phenomena, like escalating and cascading effects, may occur. The objective of the researches is to acquire knowledge about risk issues within interdependent infrastructures, to assess the usefulness of the OSCAD-based risk manager in this application domain, and to identify directions for further R&D works. The paper contains a short introduction to risk management in critical infrastructures, presents the state of the art, and the context, plan and scenarios of the performed validation experiments. Next, step by step, the validation is performed. It encompasses two collaborating infrastructure (railway, energy). It is shown how a hazardous event impacts the given infrastructure (primary and secondary effects) and the neighbouring infrastructure. In the conclusions the experiments are summarized, the OSCAD software assessed and directions of the future works identified.
We demonstrate a modularity bug in the interface system of Java 8 on the practical example of a textbook design of a modular interface for vector spaces. Our example originates in our teaching of modular object-oriented design in Java 8 to undergraduate students, simply following standard programming practices and mathematical definitions. The bug shows up as a compilation error and should be fixed with a language extension due to the importance of best practices (design fidelity).
Post-Quantum Cryptography (PQC) attempts to find cryptographic protocols resistant to attacks by means of for instance Shor’s polynomial time algorithm for numerical field problems like integer factorization (IFP) or the discrete logarithm (DLP). Other aspects are the backdoors discovered in deterministic random generators or recent advances in solving some instances of DLP. The use of alternative algebraic structures like non-commutative or non-associative partial groupoids, magmas, monoids, semigroups, quasigroups or groups, are valid choices for these new kinds of protocols. In this paper, we focus in an asymmetric cipher based on a generalized ElGamal non-arbitrated protocol using a non-commutative general linear group. The developed protocol forces a hard subgroup membership search problem into a non-commutative structure. The protocol involves at first a generalized Diffie-Hellman key interchange and further on the private and public parameters are recursively updated each time a new cipher session is launched. Security is based on a hard variation of the Generalized Symmetric Decomposition Problem (GSDP). Working with $GF(251^8)$ a 64-bits security is achieved, and if $GF(251^{16})$ is chosen, the security rises to 127-bits. An appealing feature is that there is no need for big number libraries as all arithmetic if performed in $\Z_{251}$ and therefore the new protocol is particularly useful for computational platforms with very limited capabilities like smartphones or smartcards.
In this paper we propose right-angled Artin groups as a platform for secret sharing schemes based on the efficiency (linear time) of the word problem. Inspired by previous work of Grigoriev-Shpilrain in the context of graphs, we define two new problems: Subgroup Isomorphism Problem and Group Homomorphism Problem. Based on them, we also propose two new authentication schemes. For right-angled Artin groups, the Group Homomorphism and Graph Homomorphism problems are equivalent, and the later is known to be NP-complete. In the case of the Subgroup Isomorphism problem, we bring some results due to Bridson who shows there are right-angled Artin groups in which this problem is unsolvable.
It is a consensus in signal processing that the Gaussian kernel and its partial derivatives enable the development of robust algorithms for feature detection.Fourier analysis and convolution theory have central role in such development.In this paper we collect theoretical elements to follow this avenue but using the q-Gaussian kernel that is a nonextensive generalization of the Gaussian one.Firstly, we review some theoretical elements behind the one-dimensional q-Gaussian and its Fourier transform.Then, we consider the two-dimensional q-Gaussian and we highlight the issues behind its analytical Fourier transform computation.We analyze the q-Gaussian kernel in the space and Fourier domains using the concepts of space window, cut-off frequency, and the Heisenberg inequality.
The article outlines how to use the convergence of collections to determine the position of a mobile device based on the WiFi radio signal strength with the use of fuzzy sets. The main aim is the development of the method for indoor position determination based on existing WiFi network infrastructure indoors. The approach is based on the WiFi radio infrastructure existing inside the buildings and requires operating mobile devices such as smartphones or tablets. An SQL database engine is also necessary as a widespread data interface. The SQL approach is not limited to the determination of the position but also to the creation of maps in which the system defining the position of the mobile device will operate. In addition, implementation issues are presented along with the distribution of the burden of performing calculations and the benefits of such an approach for determining the location. The authors describe how to decompose the task of determining the position in a client-server architecture.
In the research we analyzed the gas usage of different types of buildings. The analysis started with the classical theory of the buildings heating. Hence theoretical relations between gas consumption time series and the outside air temperature was introduced for different types of buildings (housing or industry). Those relations implied different auto-correlations of gas usage time series as well as different cross-correlations between gas consumption and temperature time series for different types of buildings. Hence the auto-correlation and the cross-correlation were used to imply the classification of buildings into three classes: housing, housing with high thermal capacity and industry. To investigate auto-correlation the Hurst exponent was calculated using the global DFA, while to investigate cross-correlation the Kendall's $\tau$ rank coefficient was calculated.
In the presented paper we discuss pure versions of pushdown automata that have no extra non-input symbols. More specifically, we study pure multi-pushdown automata, which have several pushdown lists. We restrict these automata by the total orders defined over their pushdowns or alphabets and determine the accepting power of the automata restricted in this way. Moreover, we explain the significance of the achieved results and relate them to some other results in the automata theory.
Extensive use of computer networks is associated with the development of various effective methods that are suitable for hiding information in the contents transferred over the network. These methods are described as network steganography. Since web applications use HTTP protocol to transmit the requests to the server and send the answers to the final recipient, specifically HTTP protocol is ideal for hiding information. For example, there are several methods that can be used to transmit the additional content in the HTTP header. In this paper, we present authors’ evaluation method for network steganography using HTTP specific properties and evaluate the effectiveness of some techniques, providing experimental results.
In this work we provide a method for approximating the separable numerical range of a matrix. We also recall the connection between restricted numerical range and entanglement of a quantum state. We show the possibility to establish state separability using computed restricted numerical range. In particular we present a method to obtain separability criteria for arbitrary system partition with use of the separable numerical range.
The article presents experiments in realistic modelling of facial expressions using volume morphing. The experiments use a variable number of points and face features. As the results are shown meshes deviations (between goal mesh and morphed shape). Experiments have shown that it is impossible to carry out a fully realistic morphing based on existing software. At the same time, even imperfect morphing allows you to show the expected emotional facial expression.
