|
|
Privacy Preserving Smart-Contract Platforms and E-Voting
Žiška, Marek ; Homoliak, Ivan (oponent) ; Perešíni, Martin (vedoucí práce)
This work examines privacy-preserving platforms Secret, Phala, and Oasis Network, which provide frameworks for development of smart contracts with confidential storage and computation capabilities. We compare these platforms based on their features such as performance, usability, and additional factors within the context of an electronic voting use case. Firstly, we establish the theoretical foundations by introducing Voting Systems, then Blockchains, Smart Contracts, Trusted Computing, and Privacy-Preserving Platforms. We analyze the development capabilities, storage options, and other features of the selected platforms and propose the design of smart contracts for the e-voting application. Following this, we implement given smart contracts, detailing our experience, the tools used, testing procedures, contruct structure, and statistics collection methods. Proposed collected statistics allow us to estimate the vote-casting throughput of our implementations. Using this metric, along with other aspects, such as the development experience, storage options, community activity, documentation quality, we evaluate and compare these platforms. At the end we conclude the achieved results, key insights, reflections, and potentional areas for future improvements.
|
|
|
Simulation of the Lighting Network Economics
Cupl, Vítězslav ; Homoliak, Ivan (oponent) ; Perešíni, Martin (vedoucí práce)
This thesis explores the security of the Lightning Network, a Layer 2 scaling solution for the Bitcoin blockchain. By simulating various attack scenarios, the research investigates the network's vulnerabilities and evaluates the effectiveness of watchtowers as a security measure. The simulations demonstrate the resilience of the Lightning Network against attacks while highlighting its limitations, particularly the trade-off between security and decentralization introduced by watchtowers. The research acknowledges the need for further exploration, including incorporating economic incentives and game theory to gain a deeper understanding of attacker behavior.
|
|
|
Blockchain Resistant to Quantum Attack
Ľaš, Michal ; Perešíni, Martin (oponent) ; Malinka, Kamil (vedoucí práce)
The development of quantum computers presents new opportunities but also introduces a threat by compromising currently used cryptographic algorithms. This threat significantly impacts blockchain technology, which relies on various cryptographic principles. The objective of this work is to design and implement a blockchain that incorporates new post-quantum cryptographic algorithms resistant to attacks performed by quantum computers. The main part of my solution involves analyzing blockchain components vulnerable to quantum attacks, selecting appropriate post-quantum algorithms, and subsequently implementing them within the blockchain. The result of this work is an overview of blockchain vulnerabilities and their solutions in the post-quantum era. Additionally, the implemented solution compares the performance of multiple post-quantum and currently used algorithms. The results show that post-quantum cryptography can have a significant impact on blockchain performance. However, post-quantum blockchains will still be usable, and they will withstand the era of quantum computers.
|
|
|
The analysis of cryptographic techniques for offloading computations and storage in blockchains
Olekšák, Samuel ; Homoliak, Ivan (oponent) ; Perešíni, Martin (vedoucí práce)
The emergence of blockchain technologies has enabled a new perspective on distributed computing and decentralised data management. However, with increasing popularity, platforms face challenges in the form of scalability, since their operation requires cryptographic principles which are computationally difficult. This thesis explores techniques that address this problem by offloading computations and storage from blockchains using zero-knowledge proofs, cryptographic accumulators and other cryptographic techniques. The second part of the thesis proposes a novel approach to implementing a blockchain-based zero-knowledge proof marketplace with proof of useful work (PoUW) consensus protocol.
|
|
|
Modeling and Simulation of Incentive Mechanisms in Ethereum
Burianová, Tereza ; Fiedor, Jan (oponent) ; Perešíni, Martin (vedoucí práce)
The topic of this thesis is the Ethereum incentive mechanism, in particular the changes introduced in EIP-1559. The aim of the thesis is to investigate the behaviour and propose any potential improvements in case of discovered flaws. The previously used first price auction mechanism required users to choose the incentive arbitrarily, which led to overpaying and high fee volatility. These problems occurred mainly due to higher network utilization after the popularization of projects such as decentralized finance, NFT collections, and the metaverse. The new incentive mechanism introduced the variable block size, which can adapt to the current network usage. Base fee, a value that indicates the minimum fee needed to include the transaction in the block, is then calculated based on the utilization of the previous block, making the fees more predictable. Several simulation experiments were proposed to investigate the typical behaviour and possible weaknesses of the mechanism. Finally, a possible improvement was found, and future research was proposed. The goals of the thesis were achieved, and the results were presented in the thesis.
|
|
|
Decentralizovaný autentizační systém založený na blockchainu
Mračna, Štefan ; Malinka, Kamil (oponent) ; Januš, Filip (vedoucí práce)
Tato práce se zabývá zavedením blockchainu do autentizačního systému, konkrétně do biometrického autentizačního systému pro otevírání dveří. Práce analyzuje různé blockchainové technologie a autentizační systémy a určuje, které technologie jsou pro tyto účely vhodné. Porovnává také centralizované a decentralizované autentizační systémy. Na základě analýzy se navrhuje decentralizovaný autentizační systém se zabudovaným blockchainem a zjednodušená verze systému, kde individuální zařízení jsou reprezentovány procesy, se implementuje. Nad tímto systémem je vytvořen program simulující provoz. Nakonec se provádí testování výkonnosti, bezpečnosti, spolehlivosti a paměťové náročnosti systému v různých podmínkách.
|
|
|
Heuristiky pro deanonymizaci v sítích kryptoměn
Anton, Matyáš ; Grégr, Matěj (oponent) ; Veselý, Vladimír (vedoucí práce)
Kryptoměny se dnes těší nebývalé oblibě, ať už díky své nezávislosti na institucích, nebo zdánlivé anonymitě, kterou poskytují. Ruku v ruce s tím však jde také jejich rostoucí zneužívání ke kriminálním aktivitám. Tato práce se zabývá zkoumáním principů a provozní praxe současných kryptoměn a technikami, které se v nich využívají pro zvýšení anonymity. Na základě zjištění následně navrhuje řešení pokoušející se o deanonymizaci aktivit v sítích vybraných kryptoměn.
|
|
| |
|
|
Biometric System Security Using Blockchain Technology
Žiška, Marek ; Drahanský, Martin (oponent) ; Malaník, Petr (vedoucí práce)
This work analyzes existing protocols used to reach consensus in blockchain technologies, describes the concepts of biometric systems, identifies their security threats, and presents existing solutions for securing the biometric systems. Based on these findings, designs a decentralized version of the biometric system that makes use of the weighted PBFT protocol and the blockchain to improve the security of feature extraction and matching module of the classical biometric system. Blockchain is characterized as a system of recording information that assures immutability. The direct use of blockchain to secure sensitive data, such as biometric data, is not expected to be the most appropriate use, but its integration within the processes of individual components of biometric systems appears to be a good option. The proposed system was implemented and tested with a variety of test scenarios. Evaluation has shown that our design managed to mitigate direct attacks on the focused components and attacks on the channels that connect them together and the channel that connects the matcher to the external application.
|
|
|
Mobile Cryptocurrency Wallet Based on zk-SNARKs and Smart Contracts
Slávka, Samuel ; Perešíni, Martin (oponent) ; Homoliak, Ivan (vedoucí práce)
The goal of this thesis is to propose and implement a framework for cryptocurrency wallets. The framework optimizes light client storage and bandwidth requirements in mobile devices. We propose a side-chain mechanism that validates blockchain header chains and creates zero-knowledge proofs. Furthermore, the framework stores the results of proof verification inside an Ethereum Smart contract. The Smart contract supports fork handling and storing header chains for multiple different blockchains. Light mobile clients using this framework can update their local header chain from checkpoints created by the proof verifications results stored in the Smart Contract. This thesis includes an implementation of a mobile wallet using this framework for synchronization with multiple blockchains.
|
host ::
RSS.