Overview

At a high level, ZetaChain is a Proof of Stake (PoS) blockchain built on the Cosmos SDK and Comet BFT consensus engine. As a result, ZetaChain enjoys fast block time (~5s) and instant finality (no confirmation needed, no re-organization allowed). The Comet BFT consensus engine has shown to scale to ~300 nodes in production. With future upgrades with BLS threshold signatures the number can potentially increase to 1000+. The throughput of transactions on ZetaChain can potentially reach 100 transactions per second TPS due to the efficiency of the consensus protocol.

The ZetaChain architecture consists of a distributed network of nodes, often referred to as validators. Validators act as decentralized observers that reach consensus on relevant connected chain state and events, and can also update connected chain state via distributed key signing. ZetaChain accomplishes these functions in a decentralized (without a single point of failure, trustless, permissionless), transparent, and efficient way.

Contained within each validator is the ZetaCore and ZetaClient. ZetaCore is responsible for producing the blockchain and maintaining the replicated state machine. ZetaClient is responsible for observing events on connected chains and signing outbound transactions.

ZetaCore and ZetaClient are bundled together and run by node operators. Anyone can become a node operator to participate in validation provided that enough bonds are staked.

Validators

Validators are comprised of 2 different roles: Core Validators and Observer-Signer Validators. Fees from transactions and rewards are distributed to validators in return for their service of processing transactions and keeping the network secure.

Core Validators

ZetaChain uses the Comet BFT consensus protocol which is a partially synchronous Byzantine Fault Tolerant (BFT) consensus algorithm. Each validator node can vote on block proposals with voting power proportional to the staking coins (ZETA), bonded/delegated. Each validator is identified by its consensus public key. Validators need to be online all the time, ready to participate in the constantly growing block production. In exchange for their service, validators will receive block rewards and transaction fees.

Observer-Signer Validators

Another set of important participants for ZetaChain consensus are the observer-signer validators who reach consensus on connected chain events and states. The observer-signers watch connected chains for certain relevant transactions/events/states at particular addresses via their full nodes of connected chains.

ZetaChain collectively holds standard ECDSA/EdDSA keys for authenticated interaction with connected chains. The keys are distributed among multiple observer-signers in such a way that only a super majority of them can sign on behalf of the ZetaChain. The ZetaChain system uses bonded stakes and positive/negative incentives to ensure economic safety.