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Security and Performance Testbed for Simulation of Proof-of-Stake Protocols
Kotráš, Jan ; Hellebrandt, Lukáš (oponent) ; Malinka, Kamil (vedoucí práce)
This diploma thesis deals with blockchain technology with focusing on the consensus protocols, especially on proof-of-stake protocols type. This thesis describes blockchain technology followed by description of consensus in this technology. First part precisely describes a comparison of specific proof-of-stake protocols based on the theoretical knowledge. Second part of thesis focuses on the design and the implementation of a testbed. The testbed is used for comparison of proof-of-stake protocols practically. In the last section of thesis, we discuss our observed properties of proof-of-stake protocols and on this basement we indicate some next ways of evolution and improvement in the consensus and proof-of-stake protocols.
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Incentive Strategies for Transaction-Fee Regime of Proof-of-Work Blockchains
Budinský, Rastislav ; Perešíni, Martin (oponent) ; Homoliak, Ivan (vedoucí práce)
In this thesis, we review the undercutting attacks in the transaction-fee-based regime of Proof-of-Work (PoW) blockchains with the longest chain fork-choice rule. Next, we focus on the problem of fluctuations in mining revenue and the mining gap -- i.e., a situation, in which the immediate reward from transaction fees does not cover miners' expenditures. To mitigate these issues, we propose a solution that splits transaction fees from a mined block into two parts -- (1) an instant reward for the miner of a block and (2) a deposit sent to one or more Fee-Redistribution Contracts ($\mathcal{FRC}$s) that are part of the consensus protocol. At the same time, these redistribution contracts reward the miner of a block with a certain fraction of the accumulated funds of the incoming fees over a predefined time. This setting enables us to achieve several interesting properties that are beneficial for the incentive stability and security of the protocol. With our solution, the fraction of \textsc{Default-Compliant} miners who strictly do not execute undercutting attack is lowered from the state-of-the-art result of 66\% to 30\%.
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An Implementation of Lattice-based Proof-of-Work on Blockchain
Krivulčík, A. ; Ricci, S.
Cryptocurrencies and blockchain are skyrocketing in recent years. They rely on Proof-of-Work (PoW) mechanisms for generating a new transaction and turn this process into ”work” (i.e., puzzles) where miners are paid for. With the advent of quantum computers, also PoW starts to migrate to post-quantum cryptographic alternatives. To the best of our knowledge, we present the first implementation of a lattice-based PoW based on the Shortest Vector Problem (SVP). By implementing in Python 3 and with the use of the NumPy library, we wrote a software that uses this concept on an artificial blockchain and demonstrates its real-world use. Even if this proposal has drawbacks on GPU optimisation and storage requirements, it shows its potential in use. The experimental results show that by balancing the size and generated range of a given matrix and vector, we can easily manipulate the time required to solve SVP challenge.
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Security and Performance Testbed for Simulation of Proof-of-Stake Protocols
Kotráš, Jan ; Hellebrandt, Lukáš (oponent) ; Malinka, Kamil (vedoucí práce)
This diploma thesis deals with blockchain technology with focusing on the consensus protocols, especially on proof-of-stake protocols type. This thesis describes blockchain technology followed by description of consensus in this technology. First part precisely describes a comparison of specific proof-of-stake protocols based on the theoretical knowledge. Second part of thesis focuses on the design and the implementation of a testbed. The testbed is used for comparison of proof-of-stake protocols practically. In the last section of thesis, we discuss our observed properties of proof-of-stake protocols and on this basement we indicate some next ways of evolution and improvement in the consensus and proof-of-stake protocols.
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Bitcoin
Herzán, Jiří ; Klíma, Tomáš (vedoucí práce) ; Veber, Jaromír (oponent)
Tato bakalářská práce se zabývá virtuální měnou bitcoin. Práce je dělena do tří částí. První kapitola se zaměřuje na kryptografii, která je využita k zabezpečení bitcoinu. V další kapitole jsou popsány principy základního fungování této kryptoměny a samotný bitcoin mining. Poslední kapitola je částí praktickou a jsou v ní otestovány dvě metody bitcoin miningu. Práce podává ucelený přehled dané problematiky se zaměřením na bitcoin mining. Hlavní cíl práce spočívá v porovnání bitcoin miningu pomocí testu ASIC mineru a metody Cloud mining. Výsledkem je potom zhodnocení výnosnosti těchto metod.
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