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Simulator for Verifying the Properties of DAG-Based Consensus Protocols
Hladký, Tomáš ; Tamaškovič, Marek (referee) ; Malinka, Kamil (advisor)
V posledných rokoch sa vo výskumnej komunite venuje blockchainu významná pozornosť. Odvtedy bolo navrhnutých niekoľko návrhov na riešenie problému priepustnosti blockchainov založených na Proof-of-Work. V tejto práci študujeme existujúce návrhy blockchainu s acyklicky orientovaným grafom (DAG), ktoré navrhujú riešenie spomínaného problému, najmä protokol PHANTOM (a jeho optiamlizácia GHOSTDAG). Využívajú bitcoinový protokol a navrhujú náhodný výber transakcií, čo vedie k zvýšeniu priepustnosti transakcií. Simuláciou sa však dokázalo, že aktéri, ktorí využívajú stratégiu náhodného výberu transakcií, majú menší zisk ako aktéri, ktorí nedodržiavajú protokol a vyberajú transakcie racionálne (t.j. najziskovejšie). Tento dôkaz bol vykonaný na malej sieti desiatich uzlov s kruhovou topológiou. Cieľom tohto článku je rozšíriť, optimalizovať a automatizovať existujúci simulátor blockchainu. Implementujeme sieťovú topológiu podobnú bitcoinu s realistickou latenciou šírenia blokov. Okrem toho optimalizujeme simulátor tak, aby sme mohli spúšťať viac simulácií paralelne a rýchlejšie, vrátane automatizačných nástrojov, ktoré môžu upravovať vstupné konfigurácie, vykonávať kombináciu simulácii na viacerých jadrách CPU na základe vstupných parametrov a analyzovať zisky a kolízie transakcií. Nakoniec vykonáme experimenty na overenie výhod škodlivých aktérov v sieti podobnej Bitcoinu a vytvoríme výplatnú funkciu na potrestanie tohto správania.
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Identification of Cryptocurrency Users
Zrnčík, Henrich ; Matoušek, Petr (referee) ; Veselý, Vladimír (advisor)
abstract.en={The 3rd January 2009 is considered to be the beginning of the cryptocurrency era. This work will deal with one of the ways of obtaining information about cryptocurrency users. It will be done by retrieving it from public websites where users often knowingly or unknowingly publish their cryptocurrency's address for different purposes (donation accounts or online payments which include personal data) as a result of which it is possible to link their crypto account with their real identity. The information is obtained through web scrappings. The result is an implemented application capable of automated collecting of data about the identity of cryptocurrency users and its subsequent storage in a structured database.
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Activity Alarm for Cryptocurrency Blockchains
Vokráčko, Lukáš ; Grégr, Matěj (referee) ; Veselý, Vladimír (advisor)
Cryptocurrencies are becoming popular and the demand for monitoring transactions inside them increases alongside with it. In this thesis, I describe few of the most widespread cryptocurrencies built on top of a blockchain and how to obtain information of their transactions in order to raise alarms. I discuss existing solutions and describe application Cryptoalarm designed for monitoring transactions involving specific addresses in order to raise alarms. Cryptoalarm scans blockchains of cryptocurrencies such as Bitcoin, Bitcoin Cash, Litecoin, Zcash, Dash, Ethereum and raises alarms about address activities in real-time.
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Secure Implementation of Blockchain Technology
Kovář, Adam ; Fujdiak, Radek (referee) ; Malina, Lukáš (advisor)
This thesis describes basis of blockchain technology implementation for SAP Cloud platform with emphasis to security and safety of critical data which are stored in blockchain. This diploma thesis implements letter of credit to see and control business process administration. It also compares all the possible technology modification. Thesis describes all elementary parts of software which are necessary to implement while storing data and secure integrity. This thesis also leverages ideal configuration of each programable block in implementation. Alternative configurations of possible solutions are described with pros and cons as well. Another part of diploma thesis is actual working implementation as a proof of concept to cover letter of credit. All parts of code are design to be stand alone to provide working concept for possible implementation and can source as a help to write productive code. User using this concept will be able to see whole process and create new statutes for whole letter of credit business process.
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Cryptocurrencies
Šindelářová, Anna ; Haupt, Jaromír (referee) ; Smutný, Milan (advisor)
Tato bakalářská práce se zaměřuje na téma Kryptoměny. Práce se zabývá vznikem a vývojem kryptoměn, jejich využitím a popisem jejich základních principů fungování. Více podrobně jsou v této práci popsány 3 vybrané kryptoměny – Bitcoin, Ethereum a Monero. Cílem této práce je provést porovnání těchto vybraných kryptoměn, které je popsáno v poslední kapitole.
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Virtual Wallet Compatible with Cryptocurrency
Marušin, Marek ; Rychlý, Marek (referee) ; Očenášek, Pavel (advisor)
The purpose of this thesis is to identify differences between classical payment systems and cryptocurrencies. A paper also compares the most well-known cryptocurrencies and explains how they work. By analyzing the principles of cryptocurrencies focused mainly on the Ethereum, we can see how virtual wallets for these digital tokens can be implemented and how we can work with custom tokens. A demonstration of created virtual wallet for Ethereum and custom ERC20 tokens is shown. Implemented practical example using Python programming language covers principles as generating private and public keys with appropriate addresses, manipulation with tokens and transactions or providing tests.
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Semi-Centralized Cryptocurrency Based on the Blockchain and Trusted Computing
Handzuš, Jakub ; Veselý, Vladimír (referee) ; Homoliak, Ivan (advisor)
The aim of this thesis is to create a concept of semi-centralized cryptocurrency that supports external interoperability. It is assumed that semi-centralized cryptocurrency is the future of cryptocurrencies in the banking sector, because even at the cost of partial centralization, the concept brings the benefits of a decentralized ledger. Since the simultaneous deployment of their own cryptocurrencies by various central authorities, such as central bank, it is necessary to establish a communication protocol for interbank transactions. The work is thus focused on extending the existing Aquareum solution with an interoperability protocol.
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Rest API for Bitcoin Network Querying
Žigo, Tomáš ; Veselý, Vladimír (referee) ; Pluskal, Jan (advisor)
This bachelor's thesis solves issues of Bitcoin network transformed data processing. The main aim of this thesis is to describe the details of Bitcoin network cryptocurrency principles and subsequently create an application which is able to process and allow access to historical data as well as actual data in the network. The solution was focused on fast synchronization and the ability to respond to requests in the shortest possible time. The problem was implemented using the NoSQL database system Cassandra with database import strategy where some data fields are updated only on request. Created solution is mostly able to compete with currently available tools.
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Information System Design
Danko, Michael ; Podešva, Lukáš (referee) ; Koch, Miloš (advisor)
The final thesis deals with the and design of the information system in the form of a conceptual design in the company Imperial invest funds s.r.o., the aim of the thesis is the efficiency of the work in the company, reducing the load of human resources, automating the processes and increasing the integrity of the IS in the functioning of the company. The main objective is to analyze existing workflows and utilization of existing information systems, and to eliminate these drawbacks or replace them with a new solution on the basis of a bottleneck analysis.
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Security and Performance Testbed for Simulation of Proof-of-Stake Protocols
Hud, Jakub ; Perešíni, Martin (referee) ; Homoliak, Ivan (advisor)
Tato práce se zabývá testováním výkonu a bezpečnosti konsensus protokolů typu Proof-of-Stake (PoS). Na teoretické úrovni porovnává protokoly ProPos, Algorand, Hedera, Ouroboros a Tezos z pohledu výkonu, možností útoků a obraně proti těmto útokům. Součástí práce je implementace simulačního frameworku v Omnet++ 5.4.1 pro provádění simulačních experimentů s protokoly ProPos, Algorand a Hedera. Simulace se zabývají zejména výkonem těchto protokolů. Na základě zjištěných výsledků jsou navržena určitá vylepšení.
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