Miracle-dz/UniFAR-FTUs huggingface dataset:
Covert-channel analysis in secure computer systems

A computer system is said to be secure if it supports the policies of a security model in a demonstrable way. Communication between two users in such a system is said to be covert if such communication is prohibited by the supported security model. Covert communication channels use system variables that cannot be included as the system's data objects to transfer information. Covert communication channels must be identified, analyzed, and handled because information can be leaked through these channels despite the system's support of a sound security model. Information flow analysis must be applied to the source code to identify all covert channels and not to top-level system specifications as practiced currently. A new method for the identification of covert storage channels in source code has been developed. The method can identify all storage channels in a computer system and can be automated. It has been applied to the kernel and trusted processes of Secure Xenix* and has led to the discovery of 24 types of storage channels. Covert-channel handling is based either on the elimination of covert channels, whenever possible, or on delay placement within each channel to lower its bandwidth under a predetermined value. The placement of large delay values, unrelated to the actual bandwidth degradation under different system and program behavior, is inadequate because it causes unnecessary performance degradation for the entire system. Accurate bandwidth and delay computation are, therefore, necessary for appropriate covert-channel handling. A Markov model has been developed to compute the maximum bandwidth of the identified covert storage channels under different system loads. Formulas for computing the maximum bandwidth and, implicitly, the minimum necessary delay have been derived. A tool for maximum bandwidth computation, and for the computation of the maximum bandwidth degradation, under different system loads has been developed in Lisp on the Unix$\dagger$ BSD 4.3 operating system. The factors affecting the bandwidth degradation in Secure Xenix, and the minimum delay for storage channels, have been identified using this tool. They are the number of users in the system and their "think times. " However, the noise introduced by unconfined processes does not degrade the covert-channel bandwidth significantly. ftn * Xenix is a trademark of the Microsoft, Inc. $\sp\dagger$Unix is a trademark of the AT&T Bell Laboratories.
Model Checking IBM's Common Cryptographic Architecture API

We present results from the application of a model checker to the analysis of the API used by a number of security modules in Automated Teller Machine networks — IBM's Common Cryptographic Architecture API. We show that it is capable of rediscovering all known attacks on the API, using models containing a greater set of API commands. We also analyse the set of recommendations released, in response to one of the discovered attacks, by IBM and show that, under certain assumptions, they do not prevent the attack. We use a revised set of assumptions, under which the attack is prevented, to determine a number of our own recommendations primarily aimed at the design and implementation of the API. Finally, we discuss various issues concerning the analysis of security APIs, based on our experiences of carrying out the work presented.
ContextML: A light-weight representation scheme for context management

Context representation is a fundamental process in developing context aware systems for the pervasive world. We present a light weight XML based context representation scheme called ContextML in which context information is categorized into scopes and related to different types of entities. Provision is made for addition of meta-information to improve the usability and quality of context information. Explanation of theContextML schema is provided with the help of real world examples.
Worst-Case Timing Analysis of Concurrently Executing DMA I/O and Programs

A hard-real-time system is required to process tasks with timing constraints that must be met to ensure the safety and correctness of the system. The analysis which determines the ability of a particular system to meet its timing constraints requires that the worst-case execution time (WCET) of each task be known in advance. The dynamic architectural features such as cache memory and instruction pipeline introduce variations in program execution times. The interference of concurrently executing cycle-stealing DMA I/O operations further complicates the problem of determining the WCET of a program. This dissertation presents methods for bounding the worst-case interference between an executing program and a cycle-stealing DMA I/O operation. We first develop a method for bounding the WCET of a program executing concurrently with cycle-stealing DMA I/O. Our method converts the problem of bounding the WCET to one of solving a integer linear programming problem. We implement our method in a timing tool and conduct extensive experiments with the timing tool to demonstrate the merits of our method. A cycle-stealing DMA I/O task is allowed to proceed only when the CPU does not need the system bus. As a result, the execution time of a cycle-stealing DMA I/O task is affected by a set of CPU tasks which execute concurrently with the I/O task. We discuss the problem of bounding the WCET of a cycle-stealing DMA I/O task under a workload which consists of a set of independent CPU tasks. Each CPU task has an arbitrary release time. We use the dynamic programming technique to bound the WCET of the I/O task.
THE T-RECS APPROACH FOR TABLE STRUCTURE RECOGNITION AND TABLE BORDER DETERMINATION

We present a snapshot of the ongoing research in the eld of table structure recognition and analysis. The prototypical T-Recs system (Table RECognition System) relies on the word level layout (bounding box geometry) as primary input. It moreover considers the textual information and potentially available delineations as further input. This article resumes the basic ideas and system features as described in [1] and [2] (downloadable from our demo page: www.dfki.uni-kl.de/ kieni/t recs/). This page also allows to interactivly load and change some prede ned documents which demonstrate the main features and strengths of the approach. Next, we will sketch some problems which encounter when applying T-Recs to business letters like o ers, invoices etc. and discuss appropriate solutions for that problem. 1 SUMMARY OF CURRENT SYSTEM Based on the word level layout information which can be derived from either OCR documents (e.g. the Xerox XDOC-format) or plain ASCII les by using a built-in preprocessor, the TRecs system performs a direct bottom-up clustering of word segments to blocks (not the conventional word-line-block order! ) and thus transforms the document representation from the word level layout to a partial logical representation (see Figure 1). Table Structures Blocksegments Wordsegments Structural Analysis Segmentation Logic
Investigation of generalized caching

This dissertation studies the replacement problem that arises in caching data objects of non-uniform size. It assumes that the cache miss penalties are also non-uniform. It formulates the problem as a discrete optimization problem, proves that it is NP-complete, and proposes an optimal solution for the off-line variant of the problem. Since the proposed solution is exponential in cache size, two off-line methods of approximating the optimal solution are proposed and explored. We also find an upper-bound on the worst-case cost of scLFD (the classical optimal paging algorithm). It extends to generalized caching a classical theorem in paging stating that prefetch caching cannot reduce the total cost. This dissertation explores the on-line variant of the problem as well. In particular, it shows that if requests are issued according to a Markov chain, the generalized caching problem becomes a special case of a Markov decision process. Then it outlines an optimal algorithm that minimizes the expected total cost over infinite horizon. Heuristic algorithms are also explored in this dissertation. We introduce the concept of specific cost for cache objects, and use it in three different heuristics. Two are variants of scLRU and scLFD. The third is a minor modification of scHARMONIC, which is a randomized on-line algorithm. All proposed heuristics are compared with competing algorithms, using actual Web traces. Also it proves that scLRU, when applied to generalized caching, is competitive, partly extending a classical result in memory paging. Finally, it presents a discussion on request sequences, introducing a characteristic function and a measure for locality of reference. It also reveals a fundamental connection between the structure of sequences and the performance of paging algorithms.
Formal Bayes Methods for Model Calibration with Uncertainty

This box describes the Bayesian approach to assessing uncertainty, and how it can be implemented to calibrate model parameters using observations, taking account of the imperfections of the model, and measurement errors. Section 1.1 outlines the justification for the Bayesian approach, Sec. 1.2 outlines the Bayesian approach to model calibration, and sections 1.3 and 1.4 discuss simple and more advanced strategies for performing the inferential calculations. There is a brief summary in Sec. 1.5. 1.1. Bayesian methods Bayesian methods provide a formal way of accounting for uncertainty, through the use of probability, and the probability calculus. Uncertainty, treated generally, is a property of the mind; it pertains to an individual, and to the knowledge that individual possesses. Many people baulk at the uncompromisingly subjective or ‘personalistic’ nature of uncertainty. A superficial understanding of science would suggest that this subjectivity is out of place, but in fact it lies at the very heart of what makes a scientist an expert in his or her field: the capacity to make informed judgements in the presence of uncertainty (Ziman, 2000, provides a naturalistic assessment of ‘real’ science). Dierent Hydrologists will produce dierent models of the same catchment, which is to say that the process of designing and constructing a model is subjective. The Bayesian approach extends this subjectivity to descriptions of uncertainty, e.g. uncertainty about the relationship between the model output and the behaviour of the actual catchment. But while model-building is something Hydrologists do a lot of, thinking about uncertainty is less familiar, and seems less structured.
Distributed interference and data buffer management for cognitive radio

Future wireless communications are focused on develop new paradigms of spectrum reuse, i.e. cognitive radio, where radio frequencies can be taken into used if no other use is detected. In this way, these systems need mechanisms for interference control. In this work we study the use of a distributed system based on cognitive radio. Scheduling transmitters and data rate optimization algorithms have been implemented in order to balance the secondary user transmissions and maximize the data rate transmission. Radio sensors are used to monitor the interference levels generated by the different transmitters. The system model has been implemented in MATLAB and analyzes its behaviour through several simulations.
Nonlinear Model Predictive Control: Theory and Algorithms

Nonlinear Model Predictive Control is a thorough and rigorous introduction to nonlinear model predictive control (NMPC) for discrete-time and sampled-data systems. NMPC is interpreted as an approximation of infinite-horizon optimal control so that important properties like closed-loop stability, inverse optimality and suboptimality can be derived in a uniform manner. These results are complemented by discussions of feasibility and robustness. NMPC schemes with and without stabilizing terminal constraints are detailed and intuitive examples illustrate the performance of different NMPC variants. An introduction to nonlinear optimal control algorithms gives insight into how the nonlinear optimisation routine the core of any NMPC controller works. An appendix covering NMPC software and accompanying software in MATLAB and C++(downloadable from www.springer.com/ISBN) enables readers to perform computer experiments exploring the possibilities and limitations of NMPC.
Error explanation and fault localization with distance metrics

When a program's correctness cannot be verified, a model checker produces a counterexample that shows a specific instance of undesirable behavior. Given this counterexample, it is up to the user to understand and correct the problem. This can be a very difficult task. The error may be in the specification, the environment or modeling assumptions, or the program itself. If the error is determined to be real, the fault localization problem remains: before the problem can be corrected, the faulty portion of the code must be identified. Industrial experience and research show that debugging is a time-consuming and difficult step of development even for expert programmers. The counterexample provided by a model checker does not provide sufficient information to ease this task. Counterexample traces can be very long and difficult to read, and often include hundreds or potentially even thousands of lines of code unrelated to the error. Error explanation is the effort to provide automated assistance in moving from a counterexample to a correction for an error. Explanation provides information as to the cause of an error and includes fault localization by indicating likely problem areas in the source code or specification. This work presents a novel and successful approach to error explanation. The approach is based on distance metrics for program executions. The use of distance metrics is inspired by the counterfactual theory of causality proposed by philosopher David Lewis, and the insights gained from previous work on providing practical error explanation.
Extended Tiny Encryption Algorithm

Masalah keamanan merupakan salah satu aspek penting dari sebuah sistem informasi. Pentingnya nilai sebuah informasi menyebabkan seringkali informasi diinginkan hanya boleh diakses oleh orang-orang tertentu. Jatuhnya informasi ke tangan pihak yang tidak diinginkan dapat menimbulkan kerugian bagi pemilik informasi. Banyak solusi yang dapat digunakan untuk menangani masalah keamanan data. Salah satu solusi untuk mengamankan data yang dikirimkan adalah dengan melakukan enkripsi (penyandian) pada data. Enkripsi dibagi menjadi dua bagian utama, yaitu algoritma simetrik dan algoritma asimetrik. Pada tugas akhir ini algoritma yang dipakai adalah algoritma XTEA yang merupakan algoritma simetrik, yaitu penyandian dengan menggunakan kunci yang sama. Data yang dikirimkan adalah data hasil enkripsi atau disebut juga ciphertext. Setelah data diterima, maka data akan diolah kembali menjadi data sebenarnya atau disebut juga plaintext. Pada tugas akhir ini berhasil direalisasikan sebuah perangkat lunak untuk pengaman data berbasis algoritma simetrik metoda XTEA dengan menggunakan bahasa pemrograman Dephi.
A Workshop on Exponential Random Graph (p*) Models for Social Networks

This article provides an introductory summary of the formulation and application of exponential random graph models for social networks. In this approach, the possible ties among nodes of a network are regarded as random variables, and assumptions about dependencies among these random tie variables determines the general form of the exponential random graph model for the network. Examples of different dependence assumptions and their associated models are given. Estimation procedures are discussed, with new methods for Monte Carlo maximum likelihood estimation briefly reviewed. Models for several well known network data sets are estimated and interpreted. The incorporation of actor attributes in social selection models is also illustrated. Newer, more complex dependence assumptions are briefly outlined, together with new model specifications (Snijders, Pattison, Robins & Handcock, in press) to which they give rise. Garry Robins, Pip Pattison, Yuval Kalish, Dean Lusher, Department of Psychology, University of Melbourne. 8 February 2005. Note: This article was originally based on a workshop given to the Social Networks and Complexity Seminar at the Kennedy School of Government, Harvard University, in February 2002. Our thanks go to David Lazer and Lars-Erik Cederman for organizing the original Harvard workshop, and to David Gibson, Department of Sociology, Harvard University. We also thank Emmanuel Lazega for permission to use his data in one of our examples.
[Clinical community genetics: exploring genetic disorders in Boyacá, Colombia].

OBJECTIVES To explore the incidence of syndromic genetic pathologies in Boyacá, Colombia, through a community genetics approach. MATERIALS AND METHODS A group made up by different medical specialists (geneticists, a pediatric neurologist, and a biochemical geneticist) developed clinical campaigns, in which patients with clinical suspicion of genetic diseases were involved. Demographic, epidemiological and clinical data were collected, and frequency calculations were made based on the collected data. Several training workshops for health personnel were done in each center visited. RESULTS Two genetic clusters were found: mucopolysaccharidosis type III, and Ellis-Van Creveld Syndrome, both of them with higher incidences than those found in the literature. Also, a high frequency of autosomal recessive diseases was found, as well as microdeletion/microduplication syndromes. CONCLUSIONS Conventional mechanisms of medical attention must be established, in order to facilitate the access to an appropriate diagnosis and treatment. This work intended to provide support to patients, families and health care services personnel through the workshops and clinical campaigns, and to become a starting point to develop primary and secondary prevention processes.
Social Software in Academia

Considerable buzz has appeared on the Internet over a group of new tools labeled social software. These tools can expand discussion beyond the classroom and provide new ways for students to collaborate and communicate within their class or around the world. Dickinson College has implemented two of the best-known tools, the wiki and the blog, in conjunction with voice over IP (VoIP) communication and social networking tools.
Code injection in C and C++: a survey of vulnerabilities and countermeasures

Implementation errors relating to memory-safety are the most common vulnerabilities used by attackers to gain control over the execution-flow of an application. By carefully crafting an exploit for these vulnerabilities, attackers can make an application transfer execution-flow to code that they have injected. Such code injection attacks are among the most powerful and common attacks against software applications. This report documents possible vulnerabilities in C and C++ applications that could lead to situations that allow for code injection and describes the techniques generally used by attackers to exploit them. A fairly large number of defense techniques have been described in literature. An important goal of this report is to give a comprehensive survey of all available preventive and defensive countermeasures that either attempt to eliminate specific vulnerabilities entirely or attempt to combat their exploitation. Finally, the report presents a synthesis of this survey that allows the reader to weigh the advantages and disadvantages of using a specific countermeasure as opposed to using another more easily. CR Subject Classification : K6.5, A.1, D3
The Use of Citations in Literary Research: A Preliminary Classification of Citation Functions

Citation studies have been concerned primarily with the properties of cited workds. The analysis of citation functions is undoubtedly more complex than this, but it can reveal information about research processes. A key problem in such an analysis is the design of categories to be used to classify citation functions. A few schemes have been created for the classification of citation functions in scientific publications. This article examines these schemes and considers differences in research methods between scientific and humanistic disciplines which might have an influence on citation practices. A scheme for the classification of citations in literary research is proposed as a preliminary model. Findings are presented from the results of the application of this scheme to a sample of publications in German literary research.
Parameter adaptation in stochastic optimization

Abstract Optimization is an important operation in many domains of science and technology. Local optimization techniques typically employ some form of iterative procedure, based on derivatives of the function to be optimized (objective function). These techniques normally involve parameters that must be set by the user, often by trial and error. Those parameters can have a strong influence on the convergence speed of the optimization. In several cases, a significant speed advantage could be gained if one could vary these parameters during the optimization, to reflect the local characteristics of the function being optimized. Some parameter adaptation methods have been proposed for this purpose, for deterministic optimization situations. For stochastic (also called on-line) optimization situations, there appears to be no simple and effective parameter adaptation method. This paper proposes a new method for parameter adaptation in stochastic optimization. The method is applicable to a wide range of objective functions, as well as to a large set of local optimization techniques. We present the derivation of the method, details of its application to gradient descent and to some of its variants, and examples of its use in the gradient optimization of several functions, as well as in the training of a multilayer perceptron by on-line backpropagation. Introduction Optimization is an operation that is often used in several different domains of science and technology. It normally consists of maximizing or minimizing a given function (called objective function ), that is chosen to represent the quality of a given system. The system may be physical, (mechanical, chemical, etc.), a mathematical model, a computer program, etc., or even a mixture of several of these.
Towards verification of Sub C programs with side effects

As the interest for formal methods grows within industry, the need for convenient and automated tools grows too. SOSSubC is an attempt to help the development of certified programs. It allows formal reasoning about imperative programs by translating programs written in SubC, a simple imperative language, into equations. Programs are then axioms of a logical system within which proofs can be carried out. In this paper, we describe how SOSSubC deals with side effects on lists and procedure parameters.
Minimal-density, RAID-6 Codes: An Approach for w = 9

RAID-6 erasure codes provide vital data integrity in modern storage systems. There is a class of RAID-6 codes called “Minimal Density Codes,” which have desirable performance properties. These codes are parameterized by a “word size,” w, and constructions of these codes are known when w and w+ 1 are prime numbers. However, there are obvious gaps for which there is no theory. An exhaustive search was used to fill in the important gap when w = 8, which is highly applicable to real-world systems, since it is a power of 2. This paper extends that approach to address the next theoretical hole at w = 9 by expanding upon the techniques used for w = 8 and adding customizations to allow for parallel processing.