Perhaps the archetypical trilemma is consensus - it requires three properties: agreement, liveness, and validity. Getting any two is easy, but all three together is what makes consensus such a facinating problem that continues to create new challenges even after 40 years of research. A lot of research focuses on...| decentralizedthoughts.github.io
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
In a previous post, we show that State Machine Replication for any $f<n$ failures is possible in the synchronous model when the adversary can only cause parties to crash. In this post, we show that omission failures are more challenging. Implementing SMR requires at most $f<n/2$ omission failures, even in...| decentralizedthoughts.github.io
In this post we explore adversary failure models that are in between crash and omission: Send Omissions (SO): the adversary can corrupt a party and decide to block any message that the party sends. The corrupted party is not aware that it is corrupted or that the message it wanted...| decentralizedthoughts.github.io
In the standard distributed computing model, the communication uncertainty is captured by an adversary that can control the message delays. The communication model defines the limits to the power of the adversary to delay messages. There are three basic communication models: the Synchronous model, the Asynchronous model, and the Partial...| decentralizedthoughts.github.io
