Highway: Efficient Consensus with Flexible Finality

01/06/2021
by   Daniel Kane, et al.
0

There has been recently a lot of progress in designing efficient partially synchronous BFT consensus protocols that are meant to serve as core consensus engines for Proof of Stake blockchain systems. While the state-of-the-art solutions attain virtually optimal performance under this theoretical model, there is still room for improvement, as several practical aspects of such systems are not captured by this model. Most notably, during regular execution, due to financial incentives in such systems, one expects an overwhelming fraction of nodes to honestly follow the protocol rules and only few of them to be faulty, most likely due to temporary network issues. Intuitively, the fact that almost all nodes behave honestly should result in stronger confidence in blocks finalized in such periods, however it is not the case under the classical model, where finality is binary. We propose Highway, a new consensus protocol that is safe and live in the classical partially synchronous BFT model, while at the same time offering practical improvements over existing solutions. Specifically, block finality in Highway is not binary but is expressed by fraction of nodes that would need to break the protocol rules in order for a block to be reverted. During periods of honest participation finality of blocks might reach well beyond 1/3 (as what would be the maximum for classical protocols), up to even 1 (complete certainty). Having finality defined this way, Highway offers flexibility with respect to the configuration of security thresholds among nodes running the protocol, allowing nodes with lower thresholds to reach finality faster than the ones requiring higher levels of confidence.

READ FULL TEXT

page 1

page 2

page 3

page 4

09/29/2021

Fast B4B: Fast BFT for Blockchains

Low latency is one of the desired properties for partially synchronous B...
10/15/2020

PoSAT: Proof-of-Work Availability andUnpredictability, without the Work

An important feature of Proof-of-Work (PoW) blockchains is full dynamic ...
05/13/2022

MOPaC: The Multiple Offers Protocol for Multilateral Negotiations with Partial Consensus

Existing protocols for multilateral negotiation require a full consensus...
04/04/2020

A Lower Bound for Byzantine Agreement and Consensus for Adaptive Adversaries using VDFs

Large scale cryptocurrencies require the participation of millions of pa...
09/20/2020

A General Framework for the Security Analysis of Blockchain Protocols

Blockchain protocols differ in fundamental ways, including the mechanics...
10/27/2021

Paving the Way for Consensus: Convergence of Block Gossip Algorithms

Gossip protocols are popular methods for average consensus problems in d...
09/10/2020

Ebb-and-Flow Protocols: A Resolution of the Availability-Finality Dilemma

The CAP theorem says that no blockchain can be live under dynamic partic...