Scalable and Resilient Byzantine Fault Tolerant Consensus
Tese submetida para provas de doutoramento em Engenharia
Informática e de Computadores Instituto Superior
Técnico, Universidade de Lisboa e no Programa de Pós-Graduação
em Engenharia de Automação e Sistemas – PPGEAS, Centro Tecnológico, da
Universidade Federal de Santa Catarina.
The increasing popularity of blockchains in addressing an expanding
set of use cases, from enterprise to governmental applications, led
to a growing interest in permissioned blockchains. In contrast to
their permissionless counterparts, permissioned blockchains can
ensure deterministic transaction finality which is a key requirement
in many settings and can offer high throughput in small-sized
systems. Some emerging use cases for per- missioned blockchains
require the system to scale to hundreds of participants. However,
most permissioned blockchains are based on variants of classical
byzantine fault-tolerant (BFT) consensus protocols that scale poorly
with the number of participants. Such scal- ability limitations stem
from bottlenecks both at the network and processing levels that
result from the large number of messages that need to be sent,
received and processed to reach consensus. Most attempts to solve
this problem on a large scale end up reducing the overall resilience
of the system and endanger both safety and liveness in the pres-
ence of byzantine failures. An approach that distributes the load
equally among a set of processes are tree-based algorithms. However,
due to the additional communication steps, tree-based approaches
still display insufficient throughput on a geographic scale. Tree
structures are also inherently more sensitive to byzantine faults,
and constructing robust trees in the presence of failures is not a
trivial matter. This thesis proposes new techniques that address
these problems. We leverage extensive pipelining to achieve high
throughput on a geographic scale independently of the depth of the
tree and present a reconfiguration algorithm that is able to
construct a robust tree in optimal steps in the presence of
failures. Experimental results show that Kauri, a prototype that
incorpo- rates the proposed techniques, can efficiently execute
consensus in settings with more than 500 participants and can
achieve up to over 58 times the throughput of competing approaches.
- Scalable and Resilient Byzantine Fault Tolerant
- PhD Thesis. Instituto Superior Técnico,
Universidade de Lisboa and Universidade Federal de Santa
- March, 2022.
- Available BibTeX and PhD Thesis
- Kauri: Scalable BFT Consensus with Pipelined
Tree-Based Dissemination and Aggregation.
R. Neiheiser, M. Matos, and L. Rodrigues.
- Proceedings of the
28th ACM Symposium on Operating Systems Principles (SOSP), Online,
video: short and long.