Apex: a High-Performance Hierarchical Distributed Ledger

Designing a secure permission distributed ledger that has the same performance a centralized counterpart, such as Visa, is a challenging task. The majority of available distributed ledgers are unable to scale to that degree. To increase the number of transactions per second, we can either compromise on security or partition the Blockchain. Here, we present Apex, a novel hierarchical distributed ledger that increases the overall performance by 1) partitioning groups of nodes into smaller concurrent distributed ledgers 2) limiting how transactions can flow to the system while guaranteeing the security and 3) combining blocks of each partition into a separate aggregated distributed ledger. Apex is designed for use-cases that require public and transparent accounting such as intellectual property rights in the music industry. An evaluation of our experimental prototype shows that Apex's throughput scales linearly with the number of active nodes while transaction confirmation is less than two seconds. By applying these tree constructs we achieve almost linear speedup in terms of transactions per second simultaneously lowering latency and verification computation-cost per node.