Дослідження сучасних блокчейн-технологій на надійність, доступність та стійкість до розгалудження

Метою даної роботи є отримання оцiнок ефективностi та надiйностi блокчейн-технологiї у сенсi САР теореми. Об’єктом дослiдження є протокол и консенс у сублокчейну Casper FFG та Proof of Work. Предметом дослiдження є надiйнiсть, доступнiсть та стiйкiсть до розгалудження блокчейну. Результатами роботи є наведенi iдеї для подальшого дослiдження надiйностi протоколу Casper FFG на етапi експлуатацiї та дослiдження невiзантiйських протоколiв консенсуса на властивостi САР теореми. Результати роботи можуть бути використанi для подальшого аналiзу систем розподiлених обчислень та алгоритмiв консенсусу. Була публiкацiя у журналi «Theoretical and Applied Cybersecurity», Серiя КВ № 23760-13600Р d/d Лютий 14, 2019The purpose of this work is getting efficiency and reliability evaluations of blockchain technology. The object of the research are blockchain consensus protocols, Casper The Friendly Finality Gadget, Proof of Work. The subject of the research is reliability, availability and patition resistance of blockchain. The results of the work are given assunptiobs and ideas about future researching reliability of Casper FFG consensus protocol and researching non byzantine consensus algorithms in terms of CAP theorem. The results of the work can be used for the further analysis of the distributed computing systems and consensus algorithms. There was a publication in the «Theoretical and Applied Cybersecurity» journal, Series КВ № 23760-13600Р d/d February 14, 2019

Identity Based Consensus for Self-Governing Systems

The selection of members is a challenge in decentralised record-keeping systems. In ‘permissioned’ systems, this crucial task is performed by a central authority or consortium. In ‘permissionless’ systems, however, the selection process is not trivial and comes with risks. Malicious actors, in a privileged position, can tamper with data, threatening the integrity of the system as a whole. Permissionless membership selection protocols, popularised with the dissemination of distributed ledger technology, have the objective of limiting the influence of a single entity on the wider network.They do so by approximating a participant’s legitimacy, to participate in record maintenance, through external or internal factors. These approximations come with downsides, in terms of attackability, system performance, supported use-cases and resource requirements. In this poster, I propose a prototypical membership selection protocol that uses the measure of personhood as an approximation of legitimacy. Interpreting a decentralised system as a political system, I frame the membership selection problem as one of political representation. I propose a protocol that democratically attributes a personhood score to members, thus creating a self-governing public decentralised system.This work in progress lays out a roadmap for the formal evaluation of self-governing public decentralised systems and describes the anticipated challenges in their implementation

The Adversary Capabilities In Practical Byzantine Fault Tolerance

The problem of Byzantine Fault Tolerance (BFT) has received a lot of attention in the last 30 years. The seminal work by Fisher, Lynch, and Paterson (FLP) shows that there does not exist a deterministic BFT protocol in complete asynchronous networks against a single failure. In order to address this challenge, researchers have designed randomized BFT protocols in asynchronous networks and deterministic BFT protocols in partial synchronous networks. For both kinds of protocols, a basic assumption is that there is an adversary that controls at most a threshold number of participating nodes and that has a full control of the message delivery order in the network. Due to the popularity of Proof of Stake (PoS) blockchains in recent years, several BFT protocols have been deployed in the large scale of Internet environment. We analyze several popular BFT protocols such as Capser FFG / CBC-FBC for Ethereum 2.0 and GRANDPA for Polkadot. Our analysis shows that the security models for these BFT protocols are slightly different from the models commonly accepted in the academic literature. For example, we show that, if the adversary has a full control of the message delivery order in the underlying network, then none of the BFT protocols for Ethereum blockchain 2.0 and Polkadot blockchain could achieve liveness even in a synchronized network. Though it is not clear whether a practical adversary could {\em actually} control and re-order the underlying message delivery system (at Internet scale) to mount these attacks, it raises an interesting question on security model gaps between academic BFT protocols and deployed BFT protocols in the Internet scale. With these analysis, this paper proposes a Casper CBC-FBC style binary BFT protocol and shows its security in the traditional academic security model with complete asynchronous networks. Finally, we propose a multi-value BFT protocol XP for complete asynchronous networks and show its security in the traditional academic BFT security model

Formal Specification and Model Checking of the Tendermint Blockchain Synchronization Protocol (Short Paper)

Blockchain synchronization is one of the core protocols of Tendermint blockchains. In this short paper, we discuss our recent efforts in formal specification of the protocol and its implementation, as well as some initial model checking results. We demonstrate that the protocol quality and understanding can be improved by writing specifications and model checking them