National Repository of Grey Literature 235 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Application of invertible elements in a zero-knowledge proof
Kučerová, Karolína ; Žemlička, Jan (advisor) ; Příhoda, Pavel (referee)
This work is focused on the description of one verifiable encryption scheme, specifically a zero-knowledge proof of knowledge protocol. Verifiable encryption allows us to prove properties of data without revealing its content. The main goal of the presented method is verification of knowledge of a secret key. This method can be used for group signa- tures, multiple steps secret sharing, key escrow protocols, and many others cryptographic protocols. It is based on the hardness of the Ring-LWE problem and problems of finding solutions to linear relations over some ring. It uses the principle of rejection sampling. The method is build on two closely described cryptographic protocols, Ring-LWE and Fiat-Shamir with aborts. It uses the construction of polynomial rings R = Z[x]/(xn + 1) a Rq = Zq[x]/(xn + 1). 1
Multivariate polynomial commitment schemes
Bžatková, Kateřina ; Hubáček, Pavel (advisor) ; Žemlička, Jan (referee)
This thesis focuses on polynomial commitment schemes - cryptographic protocols that allow committing to a polynomial and, subsequently, proving the correctness of evaluations of the committed polynomial at requested points. As our main results, we present new schemes that enable committing to multivariate polynomials and efficiently proving the correctness of evaluations at multiple points. As the main technical tools for our constructions, we use theorems from abstract algebra related to ideals of polynomial rings and some group-theoretic properties. Compared to the state-of-the-art that inspired our work, our main contribution is the improved communication complexity achieved by our protocol.
Representing Images by Weighted Finite Automata
Hurtišová, Viktória ; Holub, Štěpán (advisor) ; Žemlička, Jan (referee)
The goal of this thesis is to introduce weighted finite automata (WFA) as a means of representing multi-resolution raster images. We explain the basic concepts of weighted finite automata. Then we describe an encoding algorithm that converts an image into a WFA and a decoding algorithm that can generate back the original image. We then provide our implementation of the encoding and decoding algorithms. 1
Structural and categorical description of classes of abelian groups
Dvořák, Josef ; Žemlička, Jan (advisor) ; Modoi, George Ciprian (referee) ; Příhoda, Pavel (referee)
The work presents results concerning the self-smallness and relative smallness properties of products in the category of abelian groups and in Ab5-categories. Criteria of relative smallness of abelian groups and a characterization of self-small products of finitely generated abelian groups are also given. A decomposition theory of UD-categories and in consequence a unified theory of decomposition in categories of S-acts is developed with applications on (auto)compactness proper- ties of S-acts. A structural description of compact objects in two categories of S-acts is provided. The existence of projective covers in categories S − Act and S − Act0 and the issue of perfectness of a monoid with zero are discussed. 1
R-projectivity
Fuková, Kateřina ; Trlifaj, Jan (advisor) ; Žemlička, Jan (referee)
A module over a ring R is R-projective if it is projective relative to R. This module- theoretic notion is dual to the notion of an R-injective module that plays a key role in the classic Baer's Criterion for Injectivity. This Thesis is concerned with the validity of dual version of Baer's Criterion. It also introduces a concept of projectivity in a general category-theoretic setting. DBC is known to hold for all perfect rings. However, DBC either fails or it is undecid- able in ZFC for non-perfect rings. In this Thesis we deal with the subclass of non-perfect rings, which are small, regular, semiartinian and have primitive factors artinian. Trlifaj showed that there is an extension of ZFC in which DBC holds for such rings. Especially, it is enough to consider extension of ZFC in which the weak version of Jensen's Diamond Principle holds. This combinatorial principle is known as the Weak Diamond Principle. Apart from an overview of the properties of rings mentioned above and introduction of the necessary set-theoretic notions, the Thesis also contains a proof of this new result by Trlifaj published in the paper "Weak diamond, weak projectivity, and transfinite extensions of simple artinian rings" in the J. Algebra in 2022. 1
Functional encryption for quadratic functions
Sýkora, Josef ; Žemlička, Jan (advisor) ; Růžička, Pavel (referee)
In this thesis we will be studying functional encryption for quadratic functions. We want to encrypt a message, in form of a vector, z to a plaintext ct and create a secret key skf for a quadratic function f, which will allow us to decrypt ct to f(z), while the ct and skf will not leak any information about z. We will introduce one concrete design. The aim of this thesis will be the preparation of necessary preliminaries, which will allow us to describe the design, and to verify correctness of the algorithms. We will describe Arithmetic Branching Programs. Such objects will help us represent function f. Furthermore, we will introduce Garbling and Partial Garbling schemes. Those will allow us to "randomize"a part of the algorithm. We will also specify an encryption algorithm for linear transformation and use it to describe the main encryption algorithm for quadratic functions. 1
The entrapment of the Czech nobility by Pragues and Kutná Hora's patriciate in the year 1309 or eIse "there is no more harsher man than the ennoblement making ribald"
Musílek, Martin ; Žemlička, Josef (advisor) ; Dvořáčková, Dana (referee)
The historical research devoted only small focus on the entrapment of the Czech nobility. Generally, mainly the conclusions made by Josef Šusta had been taken into account. Specialists say that we have no chance to find something new in this subject of historical scholarship. Big deposits of silver were found near Kutná Hora during Václav's II rule. The hot symbiosis started up between the monarch and the tops of the patriciate. This friendship was bringing benefits to both of the sites of the symbiosis. The patriciates was able to do businesses and trades very easily, when the monarch stood by their side. In retum for this the patriciates was providing the valuable services to monarch, especially managing the royal chamber or helping in financial crisis. Helping in financial crisis became important during times of expensive and ambitious statesmanship of the last Přemysls. When the last of the Přemysls died, the prominent patriciates were starting to participate in political events that were shaking the whole kingdom. They were taking part in voting congresses, different missions; actually some of Czech pretendents tried to win the patriciates over. In these years the entrapment of the Czech nobility in Sedlec and in Prague also took place. When we evaluate the previous development, we have the question:...
Czech prince and Saxon duke in 12th century. Comparison of the Czech principate and Saxon duchy of Henry the Lion
Zelenka, Jan ; Žemlička, Josef (advisor) ; Bláhová, Marie (referee)
If we resume the results of our comparison, we can see that the basic difference between the duchy of Saxony, territorial domain of Henry the Lion and Bohemian principality is represented by inner political structure of these domains. In consequent this inner political structure were also the chances ofthe emperor encroach diverged. The Saxonian duchy was a conglomerate of major number of aristocratic domains. The holders of these domains (bishops, earls ..... etc.) did not subordinate to fiats of the duke, they did not grant his authority. His power and support from emperor Frederick I. Barbarossa gave him a factual dominance over the other princes of Saxony however it did not let him to beared rule over them. His effort to enlarge his own principality threatened other princes's political positions and that is why they were in constant opposition

National Repository of Grey Literature : 235 records found   previous11 - 20nextend  jump to record:
See also: similar author names
2 Žemlička, Jakub
3 Žemlička, Jan
10 Žemlička, Josef
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