Consensus
ULedger uses a Byzantine Fault Tolerant (BFT) consensus protocol. A fixed council of validator nodes agree on block order and content. Once a block is finalized by the council, it is immediately final - there is no probabilistic confirmation window.
The Council
A council is the set of validator nodes for a chain. In the standard production configuration:
| Parameter | Value |
|---|---|
| Council size | 9 nodes |
| Fault tolerance | Up to 3 Byzantine (malicious or failed) nodes |
| Consensus threshold | 66.67% (2/3) agreement required |
| Block finality | Immediate on commit |
| Max transactions per block | 200 |
Each node holds an independent copy of the full chain state. Nodes communicate via libp2p (QUIC transport, GossipSub messaging).
Block Production
Leader node proposes a block
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Council members validate proposed transactions
(ancestry checks, capability checks, blacklist checks)
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Members cast votes (3-phase BFT)
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Quorum reached (6 of 9 nodes agree)
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Block committed to all nodes
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State changes applied: wallets, entities, contracts, tokens
The leader rotates deterministically across council members.
Multi-Chain Architecture
A single council operates multiple independent chains simultaneously. In the standard deployment:
| Chain | Algorithm | Purpose |
|---|---|---|
| Principal chain | secp256k1 | Primary consensus chain |
| Member chain A | secp256k1 | Secondary member activity chain |
| Member chain B | mldsa87 | Post-quantum member chain |
Each chain has its own BFT consensus instance. A checkpoint requires quorum agreement before it is written to the principal chain.
Helix STARK Checkpoints
Beyond BFT consensus, ULedger produces cryptographic checkpoint proofs across epochs via the Helix sidecar. Each checkpoint:
- Covers an entire epoch of block headers using a Plonky3 STARK proof.
- Is recursively folded into the prior epoch's proof, producing a constant-size proof over arbitrary chain history.
- Is anchored by both
secp256k1andmldsa87signatures (cross-algorithm anchoring).
An auditor can verify the entire chain history from checkpoint proofs alone, without access to any live node.
For the full Helix proof pipeline see Helix: STARK Proof System.
Detailed References
- Consensus Mechanism (Glossary) - BFT protocol detail, leader election, voting phases
- Architecture overview - node ports, council configuration, network layer
- Helix: STARK Proof System - checkpoint generation and recursive proof folding