BFT in the lens of Blockchains and Blockchains in the lens of BFT

Lecture | August 31 | 12:30-1:30 p.m. | Soda Hall, Wozniak Lounge, 430

 Dahlia Malkhi, VMWare Research

 RISELab

Blockchain is a Byzantine Fault Tolerant (BFT) replicated state machine, in which each state-update is by itself a Turing machine with bounded resources. The core algorithm for achieving BFT in a Blockchain appears completely different from classical BFT algorithms:
• Classical solutions like DLS, PBFT solve BFT among a small-to-medium group of known participants. Such algorithms consist of multiple rounds of message exchanges carrying votes and safety-proofs. They are evidently quite intimidating to the non-expert.
• In contrast, Bitcoin solves BFT among a very large group of unknown users. In each time-period, one user broadcasts a single message carrying a Proof-of-Work (PoW). No other messages or information is exchanged.
What a difference between the two worlds!
Recent advances in blockchain technology blur these boundaries. Namely, hybrid solutions such as Byzcoin, Bitcoin-NG, Hybrid Consensus, Casper and Solida, anchor off-chain BFT decisions inside a PoW chain or the other way around. Moreover, innovative solutions in the age of blockchains, such as Honeybadger, ALGORAND, Tendermint, SBFT, and Hot-Stuff, revisit the BFT setting with greater scalability and simplicity.
Confused? Come hear this keynote in which we describe Blockchain in the lens of BFT and BFT in the lens of Blockchain, and provide common algorithmic foundations for both.

 bzar@berkeley.edu, 510-643-0264