International Association for Cryptologic Research (IACR)
Abstract
Two of the most significant challenges in the design of blockchain
protocols is increasing their transaction processing throughput and
minimising latency in terms of transaction settlement. In this work
we put forth for the first time a formal execution model that
enables to express transaction throughput while supporting formal
security arguments regarding safety and liveness. We then introduce
parallel-chains, a simple yet powerful non-black-box
composition technique for blockchain protocols. We showcase our
technique by providing two parallel-chains protocol variants, one
for the PoS and one for PoW setting, that exhibit optimal throughput
under adaptive fail-stop corruptions while they retain
their resiliency in the face of Byzantine adversity assuming honest
majority of stake or computational power, respectively. We also apply
our parallel-chains composition method to improve settlement
latency; combining parallel composition with a novel transaction
weighing mechanism we show that it is possible to scale down
the time required for a transaction to settle by any given constant
while maintaining the same level of security