Abstract

Byzantine Fault Tolerant (BFT) systems have seen extensive study for more than two decades, yet we lack a principled strategy for testing BFT implementations. In this talk I will describe Twins, a new approach for testing BFT systems. The main idea of Twins is that we can emulate Byzantine behavior by running two (or generally up to k) instances of a node with the same identity. Each of the two instances (or twins) runs unmodified, correct code. The Twins approach requires only a thin network wrapper that delivers messages to/from both twins. To the rest of the system, the twins appear indistinguishable from a single node behaving in a ‘questionable’ manner. Twins generates ‘interesting’ Byzantine behaviors, including equivocation, double voting, and losing internal state, while forgoing ‘uninteresting’ behaviors that are trivially rejected by honest nodes, such as producing semantically invalid messages. Building on this idea, Twins can systematically generate Byzantine attack scenarios at scale, execute them in a controlled manner, and check for desired protocol properties.

Bio

Shehar Bano is a Research Scientist in Novi (Facebook) based in London. She is also a Visiting Researcher at the Department of Computer Science and Technology, University of Cambridge. Her research interests centre on networked and distributed systems, particularly in the context of security and performance. She was a co-founder and senior researcher at Chainspace, a scalable smart contracts platform, before she moved to Novi. She received her Ph.D. degree (Characterization of Internet Censorship from Multiple Perspectives) from the University of Cambridge in 2017 and her Master’s degree in Computer and Communication Security from National University of Science and Technology, Pakistan in 2013.