Some Garbage In - Some Garbage Out: Asynchronous t-Byzantine as Asynchronous Benign t-resilient system with fixed t-Trojan-Horse Inputs

TL;DR

This paper demonstrates that asynchronous $t$-Byzantine faults are equivalent to $t$-resilience with malicious input alterations, simplifying the understanding of such systems and showing that recent complex methods are unnecessary.

Contribution

It establishes the equivalence between asynchronous $t$-Byzantine faults and input-resilient systems, simplifying analysis and unifying previous approaches.

Findings

Asynchronous Byzantine faults are equivalent to input-altered $t$-resilient systems.

Recent vector $oldsymbol{ extepsilon}$-agreement results are unnecessary for $t$-faults.

The system can be viewed as a synchronous system with a malicious communication adversary.

Abstract

We show that asynchronous $t$ faults Byzantine system is equivalent to asynchronous $t$-resilient system, where unbeknownst to all, the private inputs of at most $t$ processors were altered and installed by a malicious oracle. The immediate ramification is that dealing with asynchronous Byzantine systems does not call for new topological methods, as was recently employed by various researchers: Asynchronous Byzantine is a standard asynchronous system with an input caveat. It also shows that two recent independent investigations of vector $\epsilon$-agreement in the Byzantine model, and then in the fail-stop model, one was superfluous - in these problems the change of $t$ inputs allowed in the Byzantine has no effect compared to the fail-stop case. This result was motivated by the aim of casting any asynchronous system as a synchronous system where all processors are correct and it is the communication substrate in the form of message-adversary that misbehaves. Thus, in addition, we get such a characterization for the asynchronous Byzantine system.