Proof-of-Unity (PoU) Consensus

Proof-of-Unity is Savitri Network's consensus mechanism. It combines reputation-based scoring with BFT-style voting to achieve fast finality without the energy waste of Proof-of-Work or the capital lockup of Proof-of-Stake.

Score Formula

Each node maintains a PoU score updated every epoch:

S_i(t) = alpha * S_i(t-1) + (1 - alpha) * (weighted components)

Where alpha = 0.3-0.5 (smoothing factor for temporal stability).

Score Components

Component	Weight	Description
Availability	0.25-0.30	Uptime and responsiveness
Latency	0.10-0.20	Network response time
Integrity	0.20-0.25	Correct behavior, no byzantine faults
Reputation	0.20	Historical participation and reliability
Participation	0.15	Active block production and validation

Final Score

PoU_i = round(S_i(t) * 1000)

Produces a score on a 0-1000 integer scale. The node with the highest PoU score becomes the block proposer.

Election Process

1. PoU score sharing: Nodes periodically share their PoU scores via gossipsub
2. Candidate collection: Each node collects scores from group members
3. Proposer determination: Node with highest pou_score wins (peer_id tiebreaker)
4. Minimum quorum: Requires (total+1)/2 candidates to start election
5. Progressive relaxation: After 3+ consecutive failures, minimum candidates drops to 2

Election Recovery

• Watchdog timer: Re-triggers election if no block progress for 60 seconds
• Proposer rotation: After 50 blocks, proposer voluntarily steps down
• Immediate re-election: After group re-initialization, spawns PoU + election task immediately

Group Formation

Masternodes organize lightnodes into groups for parallel block production:

Masternode (coordinator)
    ├── Group A: [LN1, LN2, LN3, LN4, LN5]
    ├── Group B: [LN6, LN7, LN8, LN9, LN10]
    └── ...

• Group size: 3-7 lightnodes (configurable)
• Group ID: Deterministic based on epoch (all masternodes produce the same ID)
• Announcements: Masternodes publish group assignments every ~30 seconds
• Re-initialization: When group membership changes, scores are retained for continuing members

BFT Voting

Block finality requires a 2f+1 quorum (67% of validators):

1. Proposer produces a block
2. Block is broadcast via gossipsub (/savitri/block/1)
3. Validators verify and vote
4. Block Acceptance Certificate (BAC) is produced with 2f+1 signatures
5. Masternodes verify the BAC and finalize the block

Consensus Modes

Mode	Feature Flag	Use Case
group-aware	group-aware	Full group-based consensus
pou-based	pou-based	PoU scoring without groups
bft	bft	BFT voting only
lightweight	lightweight	Minimal consensus for mobile/embedded
full	full	All consensus features

PoU Tiers and Rewards

Tier	Min Score	Reward Multiplier
Bronze	300	1.0x
Silver	500	1.5x
Gold	700	2.0x
Platinum	900	3.0x

Nodes below score 300 do not receive rewards.

Querying PoU State

Via RPC

# Local PoU state
curl -X POST http://localhost:8545/rpc \
  -d '{"jsonrpc":"2.0","method":"savitri_pouLocal","params":[],"id":1}'

# Peer scores
curl -X POST http://localhost:8545/rpc \
  -d '{"jsonrpc":"2.0","method":"savitri_pouPeers","params":[],"id":1}'

Via SDK

let client = RpcClient::from_url("http://localhost:8545")?;

let pou = client.pou_local().await?;
println!("Score: {:?}, Leader: {:?}", pou.local_score, pou.leader);

let peers = client.pou_peers().await?;
for (peer, score) in &peers.peers {
    println!("{}: {}", peer, score);
}

Network Topology

P2P Topics:
  /savitri/tx/1                    -- Transaction broadcast
  /savitri/block/1                 -- Block broadcast
  /savitri/consensus/cert/1        -- Block acceptance certificates
  /savitri/peer_registry/1         -- Peer keepalive
  /savitri/lightnode/group/announce/1  -- Group assignments
  /savitri/group/{id}/election     -- Per-group elections

Configuration

Key consensus parameters (from config/production.toml):

Parameter	Dev	Production
Block time	2s	5s
Max TPS	100	1000
Group size	3	7
Node timeout	300s	600s
Election interval	300s	300s
PoU sharing interval	60s	60s
Latency probe interval	30s	30s