Publications by Jovan Komatovic

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This paper introduces Carbon, a high-throughput system enabling asynchronous (safe) and consensus-free (efficient) payments and votes within a dynamic set of clients. Carbon is operated by a dynamic set of validators that may be reconfigured asynchronously ...

Byzantine agreement enables n processes to agree on a common L-bit value, despite up to t > 0 arbitrary failures. A long line of work has been dedicated to improving the bit complexity of Byzantine agreement in synchrony. This has culminated in COOL, an er ...

A decision task is a distributed input-output problem in which each process starts with its input value and eventually produces its output value. Examples of such decision tasks are broad and range from consensus to reliable broadcast to lattice agreement. ...

Byzantine Agreement (BA) allows 𝑛 processes to propose input values to reach consensus on a common, valid 𝐿 𝑜-bit value, even in the presence of up to 𝑡 < 𝑛 faulty processes that can deviate arbitrarily from the protocol. Although strategies like randomiza ...

Distributed systems, which enable the efficient processing of large-scale data and complex tasks across multiple interconnected processes, offer significant advantages over single-machine systems. These include enhanced scalability, improved fault toleran ...

The Dolev-Reischuk bound says that any deterministic Byzantine consensus protocol has (at least) quadratic (in the number of processes) communication complexity in the worst case: given a system with n processes and at most f < n/3 failures, any solution t ...

Byzantine agreement allows n processes to decide on a common value, in spite of arbitrary failures. The seminal Dolev-Reischuk bound states that any deterministic solution to Byzantine agreement exchanges Ω(n2) bits. In synchronous networks, with a known u ...

Byzantine Agreement (BA) enables n processes to reach consensus on a common valid Lo-bit value, even in the presence of up to t < n faulty processes that can deviate arbitrarily from their prescribed protocol. Despite its significance, the optimal communic ...

Reliable broadcast is a communication primitive guaranteeing, intuitively, that all processes in a distributed system deliver the same set of messages. The reason why this primitive is appealing is twofold: (i) we can implement it deterministically in a co ...

Byzantine agreement, arguably the most fundamental problem in distributed computing, operates among n processes, out of which t < n can exhibit arbitrary failures. The problem states that all correct (non-faulty) processes must eventually decide (terminati ...

The Dolev-Reischuk bound says that any deterministic Byzantine consensus protocol has (at least) quadratic communication complexity in the worst case. While it has been shown that the bound is tight in synchronous environments, it is still unknown whether ...

It is known that the agreement property of the Byzantine consensus problem among n processes can be violated in a non-synchronous system if the number of faulty processes exceeds t0 = ┌n/3┐ − 1 [10], [19]. In this paper, we investigate the accountable Byza ...

The Byzantine consensus problem involves.. processes, out of which t < n could be faulty and behave arbitrarily. Three properties characterize consensus: (1) termination, requiring correct (nonfaulty) processes to eventually reach a decision, (2) agreement ...

It is well known that a trusted setup allows one to solve the Byzantine agreement problem in the presence of t < n/2 corruptions, bypassing the setup-free t < n/3 barrier. Alas, the overwhelming majority of protocols in the literature have the caveat that ...

In a non-synchronous system with n processes, no t(0)-resilient (deterministic or probabilistic) Byzantine consensus protocol can prevent a disagreement among correct processes if the number of faulty processes is > n - 2t(0). Therefore, the community defi ...

We address the problem of online payments, where users can transfer funds among themselves. We introduce Astro, a system solving this problem efficiently in a decentralized, deterministic, and completely asynchronous manner. Astro builds on the insight tha ...

Jovan Komatovic

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Carbon: Scaling Trusted Payments with Untrusted Machines

Efficient Signature-Free Validated Agreement

Crime and Punishment in Distributed Byzantine Decision Tasks

Repeated Agreement is Cheap! On Weak Accountability and Multishot Byzantine Agreement

Optimal Byzantine Agreement with Little Cryptography

Byzantine consensus is Θ(n^2): the Dolev-Reischuk bound is tight even in partial synchrony!

Partial Synchrony for Free: New Upper Bounds for Byzantine Agreement

DARE to Agree: Byzantine Agreement With Optimal Resilience and Adaptive Communication

Dynamic Byzantine Reliable Broadcast

All Byzantine Agreement Problems Are Expensive

Byzantine Consensus is Θ(n^2): The Dolev-Reischuk Bound is Tight even in Partial Synchrony!

As easy as ABC: Optimal (A)ccountable (B)yzantine (C)onsensus is easy!

On the Validity of Consensus

Juggernaut: Efficient Crypto-Agnostic Byzantine Agreement

As easy as ABC: Optimal (A)ccountable (B)yzantine (C)onsensus is easy!

Online Payments by Merely Broadcasting Messages