TINYBFT: Byzantine Fault-Tolerant Replication for Highly Resource-Constrained Embedded Systems

Byzantine fault-tolerant (BFT) state-machine replication offers resilience against a wide spectrum of faults including hardware crashes, software failures, and attacks. Unfortunately, having been mostly designed for use on large servers, existing implementations of such replication protocols consume vast amounts of memory and therefore are not available to embedded systems that consist of highly resource-constrained devices. In this paper we address this problem with TINYBFT, the first BFT state-machine replication library specifically developed to run on nodes comprising 1MB of RAM or less. To achieve this, TINYBFT relies on a memory-efficient implementation of the PBFT protocol that allocates all of its memory statically and thus, in contrast to common state-of-the-art PBFT-based libraries, has a guaranteed worst-case memory consumption that is known at compile time. Experiments show that our library provides sufficiently low latency even on tiny ESP32-C3 microcontrollers.