RillCoin Whitepaper

1. Introduction

“Wealth should flow like water.”

Concentrated wealth reduces economic velocity. When a large fraction of supply is held statically by a small number of entities, the tokens cease to participate in the productive economy. Traditional cryptocurrencies offer no mechanism to counteract this tendency — early holders and miners accumulate disproportionate balances that remain dormant indefinitely.

RillCoin's solution is algorithmic redistribution via concentration decay. When any cluster of UTXOs exceeds a configurable concentration threshold relative to the circulating supply, those holdings begin to decay at a rate determined by a sigmoid function of their concentration. Decayed tokens accrue to the active mining pool, supplementing block rewards and providing an ongoing incentive for miners to maintain the network.

The name “Rill” references a small, flowing stream — an apt metaphor for the protocol's design intent: wealth should circulate continuously rather than pool in reservoirs.

2. Protocol Constants

All constants are defined in rill-core/src/constants.rs. Integer-only arithmetic with u64 and 10⁸ fixed-point precision (1 RILL = 100,000,000 rills, the base unit).

Dev Fund

The dev fund premine of 1,050,000 RILL (5% of MAX_SUPPLY) is subject to linear vesting over 2,103,840 blocks (~4 years). At each block, a pro-rata portion of the dev fund becomes claimable by the development treasury address. This ensures long-term alignment between developers and the network.

3. Cryptography

Signatures — Ed25519

All transaction inputs are authorized with Ed25519 signatures (RFC 8032). Ed25519 provides 128-bit security, deterministic signatures, and fast batch verification — all desirable properties for a high-throughput blockchain. The public key is 32 bytes; the signature is 64 bytes.

Merkle Trees — BLAKE3

Block Merkle roots are computed using BLAKE3. BLAKE3's tree hashing mode makes it particularly well-suited for Merkle tree construction, providing both speed and parallel verification. Transaction IDs are computed as BLAKE3(bincode(transaction)).

Block Headers — SHA-256

Block headers use double SHA-256 for the proof-of-work commitment, maintaining compatibility with existing SHA-256 ASIC infrastructure. The header commits to: version, previous block hash, Merkle root, timestamp, difficulty target, and nonce.

Address Format — Bech32m

Addresses use Bech32m encoding (BIP-350) with human-readable parts:

• rill1 — Mainnet addresses
• trill1 — Testnet addresses

The address payload is the BLAKE3 hash of the Ed25519 public key, truncated to 20 bytes. Bech32m provides built-in error detection and produces human-readable, copy-paste-friendly strings.

4. Concentration Decay

See the Decay Mechanics reference page for full technical detail, including the sigmoid lookup table, fixed-point arithmetic, and lineage tracking. The following is a summary.

Concentration Metric

Concentration is measured in parts-per-billion (PPB). For a cluster with balance B and circulating supply S:

concentration_ppb = cluster_balance × 1,000,000,000 / circulating_supply

Decay Rate

The decay rate is derived from a fixed-point sigmoid function of the concentration:

decay_rate = (sigmoid(concentration_x) - 0.5) × DECAY_R_MAX_PPB × 2

where:
  DECAY_R_MAX_PPB       = 1,500,000,000  (150% per year at max concentration)
  DECAY_C_THRESHOLD_PPB = 1,000,000      (0.1% of supply — decay threshold)
  CONCENTRATION_PRECISION = 1,000,000,000

Decay Pool

Decayed amounts accumulate in the decay pool. Each block, DECAY_POOL_RELEASE_BPS = 100 (1%) of the pool is released to the block miner as supplemental reward. This creates a compounding incentive: as concentration grows, decay rates rise, increasing pool size, and increasing miner rewards.

5. Mining

RillCoin uses SHA-256 proof-of-work. Difficulty adjusts every DIFFICULTY_WINDOW (60) blocks to maintain the 60-second target. The difficulty adjustment uses a clamped ratio of actual vs. expected time, preventing extreme swings.

Block templates are served via getblocktemplate RPC. Miners compute a valid header hash below the target and submit via submitblock. The block reward is:

block_reward = subsidy(height) + tx_fees + decay_pool_release

where subsidy(height) = INITIAL_REWARD >> (height / HALVING_INTERVAL)

Coinbase outputs are subject to a maturity period of COINBASE_MATURITY = 100 blocks before they can be spent.

6. Network

RillCoin uses libp2p for all peer-to-peer communication. The network stack provides:

• Gossipsub — Block and transaction propagation
• Kademlia DHT — Peer discovery and routing
• TCP transport — Reliable message delivery

7. Storage

Node storage uses RocksDB, a high-performance LSM tree key-value store. The following column families are maintained:

• blocks — Full block data indexed by hash
• headers — Block headers indexed by hash and height
• utxos — Unspent transaction output set
• clusters — Cluster balance aggregates for decay calculation
• decay_pool — Running decay pool balance
• mempool — Pending transactions (in-memory, not persisted)

The wire protocol uses bincode for compact, deterministic serialization of all on-chain data structures. Bincode is not human-readable but provides minimal overhead for performance-sensitive consensus paths.