Motivation: Capturing Byzantine Attacks Designing distributed protocols with Byzantine Fault Tolerance (BFT) is not easy. BFT models a distributed system in which faulty nodes can behave in an arbitrary, completely unconstrained manner. However, Byzantine nodes are most likely to succeed in subverting a BFT protocol when their deviating behavior is undetectable. That is, the most … Continue reading Another Step toward High-Assurance BFT
Today, I am proud to announce that a book I edited titled ``Concurrency: The Works of Leslie Lamport'' has just been published and is available on Amazon ; Google books ; ACM books . Sharp as a razor, Leslie has unique intuition and insights on distributed systems that bring clarity and new angles on problems. Those of us who collaborated … Continue reading Concurrency
A few months ago, Ittai Abraham posed a challenge on whether we can have a ledger that can support "heterogeneous" clients. Independently, in a conversation, Ben Maurer asked if different transactions could be provided with different assurance levels. In a recent preliminary report on Arxiv, Dahlia, Ling and I answer these and other related questions; … Continue reading Flexible Byzantine Fault Tolerance
Did you ever wonder what is the BFT consensus engine that drives Dfinity, is it new or known, and how can it be improved? With co-authors at VMware Research , we explored the DFINITY Technology Overview Series on the Consensus System, and report our insights in a recent note on the Cryptology ePrint Archive .
Renewed interest in the Blockchain world on a long standing problem of asynchronous Byzantine Fault Tolerant (BFT) Consensus focuses on the following scaling challenges: Chain Quality necessitates fast/frequent proposer rotation for fairness and liveness Linearity means paying a communication cost that amounts to sending a proposal over the network once to everyone. This cost is kept … Continue reading HotStuff: Three-chain Rules!
In a 2014 piece to the NYTimes, Marc Andreesen wrote: “Bitcoin is the first practical solution to a longstanding problem in computer science called the Byzantine Generals Problem.” This was both an insightful comment and an overly optimistic one. It shed insight to the link between the decentralization technology of Bitcoin and the world of distributed … Continue reading Blockchain in the lens of BFT
This is the second post in a series discussing: Today I am going to overview the Tendermint core, a BFT algorithm described in several white-papers [tendermint wiki, Buchman's thesis 2016, Kwon's manuscript 2014]. Tendermint was the first in a series of "permissioned" blockchain BFT solutions based off PBFT, followed by Casper and Hot-Stuff. The algorithm below borrows … Continue reading The BFT lens: Tendermint
This post is the first in a series discussing: Today I am going to overview a new algorithmic foundation called ‘Hot-Stuff the Linear, Optimal-Resilience, One-Message BFT Devil’ (in short, Hot-Stuff), developed jointly with my colleagues Ittai Abraham and Guy Gueta, and harness it to explain the safety and liveness of Casper the Friendly Finality Gadget. The key take-aways are: We have excellent … Continue reading The BFT lens: Hot-Stuff and Casper
Over a decade of improvements to the seminal PBFT work have turned out to have safety or liveness issues, as demonstrated in a recent ArXiv note we posted: Revisiting Fast Practical Byzantine Fault Tolerance. Ittai Abraham, Guy Gueta, Dahlia Malkhi; with Lorenzo Alvisi, Rama Kotla, Jean-Philippe Martin. [ArXiv 2017] [pdf]