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Decompilation of Selected C++ Constructions
Mihulka, Tomáš ; Zemek, Petr (referee) ; Matula, Peter (advisor)
This bachelor's thesis deals with the reconstruction of a hierarchy of classes and their virtual methods from programmes created by C++ language . The aim of this work is to extend a decompiler , which has been developed as a part of the Lissom project, by an analysis of those reconstructions for various decompilers . The reconstructions are created through detection of RTTI and virtual tables . The first part of this thesis involves a description of reverse engineering as well as of the Lissom project in terms of the decompiler . The following section of the paper explains the basics of C++ language , its structures and different possibilities of their decompilation . The final part of the paper deals with a design, implementation and testing of a recognition of RTTI and virtual tables .
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Linux Software Protection Against Reverse Engineering
Korec, Tomáš ; Zemek, Petr (referee) ; Hruška, Tomáš (advisor)
This thesis deals with an implementation of Linux software protection against reverse engineering within the Lissom project. Protection consists of three layers. The first layer is represented by methods detecting tools, that enable the application of reverse engineering methods. Protection based on hashing the functions represents the second layer which protects the application against changes. The third layer of protection is a binary parts file encryption. These methods complete an existing license server of the Lissom project. Possible future extensions are discussed at the end of the thesis.
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Automata with a Limited Number of Pure Pushdowns
Soukup, Ondřej ; Zemek, Petr (referee) ; Meduna, Alexandr (advisor)
Pushdown automata with limited number of pure pushdowns are specialization of pure pushdown automata. Examination of their power is mainly focused on the view of combinatorics of words. In language defined by automata we introduce term of dependence, which denotes relation between parts of strings in language. It is shown, how the defined automata proceed on processing of dependencies. Then the relation between distribution of dependencies in language and required number of pushdowns is derived. Also is defined the infinite hierarchy of languages corresponding to automata in dependence on number of their pushdowns. At the end belonging of the class of languages defined by pushdown automata with limited number of pure pushdowns to Chomsky hierarchy of languages is studied, but it is discovered, that they do not correspond to Chomsky hierarchy. Based on this result it is proposed to study possible changes of models as a future development. Then the simulating program is created to illustrate features of examined automata.
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Canonical Derivations in Programmed Grammars
Zemek, Petr ; Masopust, Tomáš (referee) ; Meduna, Alexandr (advisor)
This work studies canonical derivations (with focus on leftmost derivations) in programmed grammars and left restriction range. It is shown that if we introduce n-limited derivations in programmed grammars as they were defined for state grammars, we get an infinite hierarchy of language families resulting from n-limited programmed grammars, so the left restriction range affects the generative power of n-limited programmed grammars. This result is significant for syntactical analysis based on programmed grammars.
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C Back-End for a Decompiler
Urban, Martin ; Ďurfina, Lukáš (referee) ; Zemek, Petr (advisor)
This thesis deals with the implementation of the back-end of the decompiler, which produces a code in C language. It contains basic information about the principals and using of the reverse engineering either in the area of information technology or apart from it. The main goal is to create the back-end of the decompiler which would generate a code that would be equivalent against the input and will be translatable into a binary code. Functionality of the output code will be conserved in state of the functionality of the source code. The output is the implementation of the classes in C++ language. It does described activity as a part of the general decompiler which is developed in terms of the project Lissom.
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Transformation of Grammars into Normal Forms
Klapuchová, Mirka ; Koutný, Jiří (referee) ; Zemek, Petr (advisor)
This thesis deals with issues of normal forms from theory of formal languages. Basic terms from this area are listed here, different types of grammars as well and especially normal forms and algorithms that transfer grammars into normal forms. Description of design and implementation of program which is used to transfer input grammar into entered normal form is included.
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Compiler Warnings Filter
Krajčovičová, Mária ; Horáček, Petr (referee) ; Zemek, Petr (advisor)
Goal of this bachelor's thesis was design and implementation of program which filtrate warnings from compiler output without hitting the source codes. The bachelor's thesis describes compilers as GCC, Clang, Javac and GHC. It describes also their functionality and types of warnings from their outputs. Result of the bachelor's thesis is an application which is able warning filltration for mentioned compilers.
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Optimizations in the Decompiler's Back-End
Kollár, Jaroslav ; Ďurfina, Lukáš (referee) ; Zemek, Petr (advisor)
This bachelor's thesis describes the design and implementation of optimizations in the retargetable decompiler's back-end. The purpose of these optimizations is to improve readability of the produced source code. In the introduction, basic information about reverse engineering and decompilation is provided. Then, there is an analysis of the source code produced by the decompiler to familiarize the reader with the proposed optimizations. After that, there is the main part of this work, which describes the design and implementation of the proposed optimizations. It is followed by mentioning the techniques that were used for testing. The present work is concluded by a summary of the achieved results and their benefits.
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On Erasing Rules in Regulated Grammars
Zemek, Petr ; Koutný, Jiří (referee) ; Meduna, Alexandr (advisor)
This work discusses the effect of erasing rules to the generative power of regulated grammars, which is a big open problem in the theory of regulated rewriting. It studies the possibility of removal of erasing rules from regulated grammars by aggregation of current, up-to-date results concerning this elimination and by presentation of a new condition, called k-limited erasing, under which all erasing rules can be always removed from regularly controlled context-free grammars without affecting their generative power. This result partially solves the abovementioned problem. Moreover, a new algorithm for elimination of erasing rules from context-free grammars is presented. This algorithm does not require any predetermination of so called epsilon-nonterminals (in contrast to the standard algorithm used in textbooks). In the conclusion, a significance of these results concerning syntactical analysis is discussed.
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Generic Decompilation of Bytecode into High-Level Representation
Mrázek, Petr ; Zemek, Petr (referee) ; Křoustek, Jakub (advisor)
The work describes methods and principles of decompilation, basic information about reverse engineering and its use in both software engineering and engineering in general. Furthermore, it introduces the decompiler developed within the Lissom project at BUT FIT. The goal of the work is to design and implement a retargetable decompiler for bytecode, which extends the original decompiler.
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