This post is about the classic result from 1983 on authenticated broadcast against a Byzantine adversary: Theorem (Dolev-Strong [1983]): there exists an authenticated protocol for solving broadcast, against any adversary controlling $t<n$ out of $n$ parties, in $t+1$ rounds, using $O(n^2t)$ words Recall Broadcast properties: (1) Termination - all honest...| decentralizedthoughts.github.io
We introduced definitions for consensus, Byzantine Broadcast (BB) and Byzantine Agreement (BA), in an earlier post. In this post, we discuss how consensus protocols are used in State Machine Replication (SMR), a fundamental approach in distributed computing for building fault-tolerant systems. We compare and contrast this setting to that of...| decentralizedthoughts.github.io
Post updated in March 2021 Different modeling assumptions under which we construct BFT protocols often make it hard to compare two protocols and understand their relative contributions. In this post we discuss synchronous protocols in the authenticated model (assuming a PKI). A protocol runs in the synchronous model if it...| decentralizedthoughts.github.io
Here at decentralized thoughts, we spend a lot of time reasoning about distributed protocols. Often, we focus on solving distributed consensus, personally it’s my favorite CS problem, but it’s also famously one of the most difficult and subtle problems in distributed computing. Reasoning about distributed algorithms is hard at the...| decentralizedthoughts.github.io
Many systems try to optimize executions that are failure free. If we absolutely knew that there will be no failures, parties could simply send each other messages with our inputs and reach consensus by outputting, say, the majority value. Thus completing the protocol after one round. What happens if there...| decentralizedthoughts.github.io
