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Andrei Lebedev

Publications and source records attributed to Andrei Lebedev.

8 recordsLinked to original sources
arXiv2026

Blockchain Communication Vulnerabilities

Blockchains are diverse in the way they handle communications between their nodes to disseminate information, mitigate attacks, and agree on the next block. While security vulnerabilities have been identified, they rely on an attack custom-made for a specific blockchain communication protocol. To our knowledge, the vulnerabilities of multiple blockchain communication protocols to adversarial conditions have never been compared. In this paper, we compare empirically the vulnerabilities of the communication protocols of five modern in-production blockchains, Algorand, Aptos, Avalanche, Redbelly and Solana, when attacked in five different ways. We conclude that Algorand is vulnerable to packet loss attacks, Aptos is vulnerable to targeted load attacks and leader isolation attacks, Avalanche is vulnerable to transient failure attacks, Redbelly's performance is impacted by packet loss attacks and Solana is vulnerable to stopping attacks and leader isolation attacks. Our system is open source.

cs.CR↗
arXiv2026

On the Bandwidth Consumption of Blockchains

With the advent of blockchain technology, the number of proposals has boomed. The network traffic imposed by these blockchain proposals increases the cost of hosting nodes. Unfortunately, as of today, we are not aware of any comparative study of the bandwidth consumption of blockchains. In this paper, we propose the first empirical comparison of blockchain bandwidth consumption. To this end, we measure the network traffic of blockchain network nodes of five blockchain protocols: Algorand, Aptos, Avalanche, Redbelly and Solana. We study the variation over time, differentiate the receiving and sending traffic and analyze how this traffic varies with the number of nodes and validators. We conclude that the transport protocol is the main factor impacting the network traffic, segregating node roles helps reduce traffic and different blockchains are differently impacted by the network size.

cs.DC↗
arXiv2024

Stabl: Blockchain Fault Tolerance

Blockchain promises to make online services more fault tolerant due to their inherent distributed nature. Their ability to execute arbitrary programs in different geo-distributed regions and on diverse operating systems make them an alternative of choice to our dependence on unique software whose recent failure affected 8.5 millions of machines. As of today, it remains, however, unclear whether blockchains can truly tolerate failures. In this paper, we assess the fault tolerance of blockchain. To this end, we inject failures in controlled deployments of five modern blockchain systems, namely Algorand, Aptos, Avalanche, Redbelly and Solana. We introduce a novel sensitivity metric, interesting in its own right, as the difference between the integrals of two cumulative distribution functions, one obtained in a baseline environment and one obtained in an adversarial environment. Our results indicate that (i) all blockchains except Redbelly are highly impacted by the failure of a small part of their network, (ii) Avalanche and Redbelly benefit from the redundant information needed for Byzantine fault tolerance while others are hampered by it, and more dramatically (iii) Avalanche and Solana cannot recover from localised transient failures.

cs.DC↗
arXiv2024

Differentiation of resultants and common roots of pairs of polynomials

The well-known mathematical instrument for detection common roots for pairs of polynomials and multiple roots of polynomials are resultants and discriminants. For a pair of polynomials $f$ and $g$ their resultant $R(f,g)$ is a function of their coefficients. Zeros of resultant $R(f,g)$ correspond to the families of coefficients of $f$ and $g$ such that $f$ and $g$ have a common root. Herewith the calculation of this common root is a separate problem. The principal results on calculation of a unique common root of two polynomials and also about calculating a unique root of multiplicity 2 of a polynomial in terms of the first order partial derivatives of resultants and discriminants are given in the monograph by I.M. Gelfand, M.M. Kapranov, A.V. Zelevinsky [1, Ch. 3, Ch. 12]. A significant development of the ideas of this book in the direction of searching for formulas for multiple roots of polynomials is presented in the paper by I.A. Antipova, E.N. Mikhalkin, A.K. Tsikh [2]. The key result of this article is [2, Theorem 1] where the expression for a unique root of multiplicity $s \geq 3$ in terms of the first order partial derivatives of resultant of the polynomial and it's derivative of order $s-1$. In the present article the explicit formulas for higher derivatives of resultants of pairs of polynomials possessing common roots are obtained. On this basis a series of results that differ in ideas from [2, Theorem 1] linking higher derivatives of resultants and common multiple roots are proven. In addition the results obtained are applied for a new transparent proof of a refinement of [2, Theorem 1].

math.CA↗
arXiv2023

On the Relevance of Blockchain Evaluations on Bare Metal

In this paper, we present the first bare metal comparison of modern blockchains, including Algorand, Avalanche, Diem, Ethereum, Quorum and Solana. This evaluation was conducted with the recent Diablo benchmark suite, a framework to evaluate the performance of different blockchains on the same ground. By tuning network delays in our controlled environment we were able to reproduce performance trends obtained in geo-distributed settings, hence demonstrating the relevance of bare metal evaluations to better understand blockchain performance.

cs.DC↗
arXiv2018

YAC: BFT Consensus Algorithm for Blockchain

Consensus in decentralized systems that asynchronously receive events and which are subject to Byzantine faults is a common problem with many real-life applications. Advances in decentralized systems, such as distributed ledger (i.e., blockchain) technology, has only increased the importance of finding performant and secure solutions to consensus of state machine replication in decentralized systems. YAC is a practical decentralized consensus algorithm, that solves the problems of inefficient message passing and strong leaders that occur in classical Byzantine fault tolerant consensus algorithms. The algorithm is open source and currently is used to provide Byzantine fault tolerant consensus for the Hyperledger Iroha blockchain project. We provide proofs of safety and liveness, as well as empirical results showing that our algorithm can scale to dozens of validating peers.

cs.DC↗
arXiv2017

Link Prediction using Top-$k$ Shortest Distances

In this paper, we apply an efficient top-$k$ shortest distance routing algorithm to the link prediction problem and test its efficacy. We compare the results with other base line and state-of-the-art methods as well as with the shortest path. Our results show that using top-$k$ distances as a similarity measure outperforms classical similarity measures such as Jaccard and Adamic/Adar.

cs.SI↗