P-Chain - Core Platform Specification

Abstract

LP-1000 specifies the P-Chain (Platform Chain), Lux Network's metadata and coordination blockchain. The P-Chain manages validator sets, staking operations, chain coordination, and chain creation. It operates using Lux consensus optimized for platform operations.

Motivation

A dedicated platform chain provides:

1. Validator Management: Centralized tracking of all network validators
2. Staking Operations: Handle staking, delegation, and rewards
3. chain Coordination: Manage chain creation and membership
4. Chain Creation: Enable permissionless blockchain deployment

Specification

Chain Parameters

Parameter	Value
Chain ID	P
VM ID	platformvm
VM Name	platformvm
Block Time	2 seconds
Consensus	Lux (Linear)

Implementation

Go Package: github.com/luxfi/node/vms/platformvm

import (
    pvm "github.com/luxfi/node/vms/platformvm"
    "github.com/luxfi/node/utils/constants"
)

// VM ID constant
var PlatformVMID = constants.PlatformVMID // ids.ID{'p', 'l', 'a', 't', 'f', 'o', 'r', 'm', 'v', 'm'}

// Create P-Chain VM
factory := &pvm.Factory{}
vm, err := factory.New(logger)

Directory Structure

node/vms/platformvm/
├── block/            # Block definitions and execution
├── config/           # Chain configuration
├── reward/           # Reward calculation engine
├── signer/           # Transaction signing
├── state/            # Validator and staking state
├── txs/              # Transaction types
├── warp/             # Cross-chain messaging
├── factory.go        # VM factory
├── vm.go             # Main VM implementation
└── *_test.go         # Tests

Core Responsibilities

1. Validator Management: Track and coordinate all network validators
2. Staking Operations: Handle staking, delegation, and rewards
3. chain Coordination: Manage chain creation and membership
4. Chain Creation: Enable permissionless blockchain deployment

Transaction Types

Type	Description
AddValidatorTx	Add a validator to the primary network
AddDelegatorTx	Delegate stake to a validator
CreateChainTx	Create a new chain
CreateBlockchainTx	Create a new blockchain
AddChainValidatorTx	Add validator to chain
RemoveChainValidatorTx	Remove validator from chain
TransformChainTx	Transform chain to elastic chain

Staking Parameters

Parameter	Value
Minimum Validator Stake	2,000 LUX
Maximum Validator Stake	3,000,000 LUX
Minimum Delegation	25 LUX
Minimum Duration	2 weeks
Maximum Duration	1 year
Maximum Delegation Ratio	5x validator stake

Staking Rewards

Annual Percentage Yield (APY) = f(totalStaked, supplyRemaining)

Where:
- Maximum APY: 11% (at 50% network staked)
- Minimum APY: 7% (at 80% network staked)
- Rewards decrease as total stake increases

API Endpoints

RPC Methods

Method	Description
platform.getCurrentValidators	Get current validator set
platform.getPendingValidators	Get pending validators
platform.getStake	Get stake information
platform.addValidator	Add validator transaction
platform.addDelegator	Add delegator transaction
platform.createChain	Create chain transaction
platform.createBlockchain	Create blockchain transaction

REST Endpoints

GET  /ext/bc/P/validators/current
GET  /ext/bc/P/validators/pending
GET  /ext/bc/P/stake/{address}
POST /ext/bc/P/validators/add
POST /ext/bc/P/delegators/add
POST /ext/bc/P/chains/register
POST /ext/bc/P/blockchains/create

recursive network architecture

type chain struct {
    ID           ids.ID
    ControlKeys  []Address
    Threshold    uint32
    Blockchains  []BlockchainID
    Validators   ValidatorSet
}

chain Properties:

• Primary Network: All validators must validate
• chains: Subset of primary validators
• Weight: Determines influence in consensus

UTXO Model

P-Chain uses a UTXO model for:

• Tracking staked funds
• Managing locked outputs
• Handling rewards distribution

UTXO States:
1. Available → Staked (via AddValidator)
2. Staked → Locked (during validation)
3. Locked → Available + Rewards (after validation)

Consensus Integration

P-Chain uses Lux consensus (linear chain):

• Finality: ~2 seconds
• Byzantine fault tolerance: 80% honest stake
• No forks or uncles

Configuration

{
  "platformvm": {
    "minValidatorStake": 2000000000000,
    "maxValidatorStake": 3000000000000000,
    "minDelegatorStake": 25000000000,
    "minStakeDuration": 1209600,
    "maxStakeDuration": 31536000,
    "rewardConfig": {
      "maxConsumptionRate": 120000,
      "minConsumptionRate": 100000,
      "mintingPeriod": 31536000,
      "supplyCap": 720000000000000000
    }
  }
}

Rationale

Design decisions for P-Chain:

1. Separate Chain: Platform operations isolated from transaction chains
2. UTXO Model: Simple state tracking for staking operations
3. Linear Chain: No need for DAG structure for platform operations
4. Quasar Integration: Compatible with quantum-safe consensus

Backwards Compatibility

LP-1000 supersedes LP-0010. Both old and new numbers resolve to this document.

Test Cases

See github.com/luxfi/node/vms/platformvm/*_test.go:

func TestAddValidatorTx(t *testing.T)
func TestAddDelegatorTx(t *testing.T)
func TestCreateChainTx(t *testing.T)
func TestCreateBlockchainTx(t *testing.T)
func TestRewardCalculation(t *testing.T)
func TestUTXOStateTransitions(t *testing.T)

Reference Implementation

Repository: github.com/luxfi/node Package: vms/platformvm Dependencies:

• github.com/luxfi/node/vms/platformvm/state
• github.com/luxfi/node/vms/platformvm/txs
• github.com/luxfi/node/vms/platformvm/reward

Security Considerations

1. Sybil Resistance: Minimum stake requirements prevent cheap validator spam
2. Stake Locking: Validators cannot unstake during validation period
3. Delegation Limits: 5x cap prevents excessive concentration
4. Key Management: Validator keys must be kept secure

Related LPs

LP	Title	Relationship
LP-0010	P-Chain Platform Specification	Superseded by this LP
LP-1100	Validator Management	Sub-specification
LP-1200	Staking Mechanics	Sub-specification
LP-1300	chain Management	Sub-specification

Copyright

Copyright and related rights waived via CC0.