Hot Stuff BFT Consensus in the Lens of

Hot. Stuff: BFT Consensus in the Lens of Blockchain Weisu Yin, Weijia Xing

Overview ● Why Hot. Stuff ● Basic Hot. Stuff ● Chained Hot. Stuff

Why Hot. Stuff ● BFT SMR protocols target system size was small ● PBFT is complex and slow

Why Hot. Stuff ● Linear View Change ● Optimistic Responsiveness

Leader A phase in PBFT

Leader A phase in Hot. Stuff Leader

Basic Hot. Stuff Three Phases: 1. Prepare 2. Pre-Commit 3. Commit Plus a decide phase

Basic Hot. Stuff ● Each replica maintains a tree, in which a node represents a commit ● QC(quorum certificate) is a structure containing: ○ ○ ○ Types View. Number A node

Basic Hot. Stuff

Basic Hotstuff

Basic Hot. Stuff

Chained Hot. Stuff What could be a possible improvement? Prepare phase (We are going to do this) Pre-commit phase (Maybe do stuff) Commit phase (Definitely do stuff)

5 -segment Pipeline Processor

Chained Hot. Stuff Pipeline involved: Chained Hot. Stuff is a pipelined Basic Hot. Stuff where a QC can serve in different phases simultaneously.

Chained Hot. Stuff: Critical Problems 1. Generic. QC 2. Execute or not? 3. Interruption/disconnection happened?

Generic. QC(1/2) precommit. QC generic. QC prepare. QC There are only two types of messages in Chained Hot. Stuff, a new-view message and generic -phase generic message. The generic QC functions in all logically pipelined phases.

Node structure and generic. QC: same to the Basic Hot. Stuff Node { parent: Node cmd: CMD justify: QC } ○ ○ ○ Types View. Number A node

Generic. QC(2/2) Generic. QC is determined by: 1. QC received from leader of current view; if not, then by 2. high. QC with maximum view. Number: if high. QC. view. Number > generic. QC. view. Number then generic. QC <- high. QC

Execute a command Nodes at views v 3, v 4, v 5, v 6 form a Three-chain.

Interrupt/Disconnection Dummy Node: 1. Fails to obtain a QC. 2. Extends generic. QC. node with blank nodes.

Performance - Hot. Stuff vs BFT-SMa. Rt

Questions?

Thanks!