Consensus

The Midnight network leverages a modified consensus model built on top of standard Substrate primitives, specifically AURA for block production and GRANDPA for finality. These components have been extended to support the unique requirements of Midnight as a Cardano Partnerchain.

Validator Selection

Unlike standard Substrate chains, Midnight uses a custom validator set selection function. This mechanism accounts for stake delegation from Cardano SPOs, allowing existing Cardano validators to participate in Midnight consensus. The model also supports optional inclusion of permissioned validators, offering flexibility for hybrid public/private network deployments.

AURA: Block Production

AURA (Authority Round) is a proof-of-authority (PoA) algorithm used to determine which validator is responsible for producing each block. Validators take turns in a round-robin fashion, based on predefined slots and session keys. This model is simple, fast, and deterministic, making it suitable for high-throughput blockchains with known validator sets.

AURA is not specific to Midnight and was originally implemented in OpenEthereum. You can read more in the Polkadot protocol glossary.

GRANDPA: Finality

GRANDPA (GHOST-based Recursive ANcestor Deriving Prefix Agreement) is a finality gadget that provides asynchronous, provable finality. It operates independently of block production, allowing validators to vote on chains and finalize blocks that have received sufficient support.

GRANDPA is a general-purpose consensus component originally developed for Polkadot and is not specific to Midnight. You can find its formal specification here and learn more in the Polkadot protocol glossary.