  The spectacular success of Bitcoin and Blockchain Technology in recent years
has provided enough evidence that a widespread adoption of a common
cryptocurrency system is not merely a distant vision, but a scenario that might
come true in the near future. However, the presence of Bitcoin's obvious
shortcomings such as excessive electricity consumption, unsatisfying
transaction throughput, and large validation time (latency) makes it clear that
a new, more efficient system is needed.
  We propose a protocol in which a set of nodes maintains and updates a linear
ordering of transactions that are being submitted by users. Virtually every
cryptocurrency system has such a protocol at its core, and it is the efficiency
of this protocol that determines the overall throughput and latency of the
system. We develop our protocol on the grounds of the well-established field of
Asynchronous Byzantine Fault Tolerant (ABFT) systems. This allows us to
formally reason about correctness, efficiency, and security in the strictest
possible model, and thus convincingly prove the overall robustness of our
solution.
  Our protocol improves upon the state-of-the-art HoneyBadgerBFT by Miller et
al. by reducing the asymptotic latency while matching the optimal communication
complexity. Furthermore, in contrast to the above, our protocol does not
require a trusted dealer thanks to a novel implementation of a trustless ABFT
Randomness Beacon.
