When They Go Low: Automated Replacement of Low-level Functions in Ethereum Smart Contracts

Low latency is one of the desired properties for partially synchronous Byzantine consensus protocols. Previous protocols have achieved consensus with just two communication steps either by reducing the upper bound on the number of faults the protocol can tolerate (f = (n+1)/5) or use of trusted hardware like Trusted Execution Environment or TEEs. In this paper, we propose a protocol called VBFT, in which the protocol achieves consensus in just two communication steps. VBFT can tolerate maximum number of faults a partial BFT consensus can tolerate (f = (n−1)/3). Furthermore, VBFT does not require the use of any trusted hardware. The trade-off for this achievement is that at most f nodes nodes may revert their blocks for small number times. We show that this reversion of a block will not compromise the safety of the protocol at all, yet it may incur a small amount of additional latency during view change.