Validator Manager Contract

When discussing the Validator Manager Contract structure for Permissioned L1s we only saw part of the overall strucure. In the mermaid diagram below you can see an expanded view of it, with three new contracts:

• PoSValidatorManager
• ERC20TokenStakingManager
• NativeTokenStakingManager

Check out the complete diagram and code implementation on github.

PoSValidatorManager

Proof-of-Stake Validator management is provided by the abstract contract PoSValidatorManager, which has two concrete implementations: NativeTokenStakingManager and ERC20TokenStakingManager.

This abstract contract extends ValidatorManager by adding functions for permissionless validator registration and removal based on staked tokens. In addition to basic Validator management, PoSValidatorManager supports uptime-based Validation rewards, as well as Delegation to a Validator.

The choice between NativeTokenStakingManager and ERC20TokenStakingManager depends on what type of token you want validators to stake—the L1's native token or a separate ERC20 token.

NativeTokenStakingManager

NativeTokenStakingManager allows permissionless addition and removal of validators who stake the L1's native token. This implementation uses Solidity's payable keyword to accept native tokens directly through function calls.

Key Functions

• initiateValidatorRegistration(...) payable - Accepts native tokens via msg.value to lock as stake
• initiateDelegatorRegistration(...) payable - Allows delegators to stake native tokens to a validator
• _lock(value) - Simply returns the value (tokens are already locked in the contract)
• _unlock(to, value) - Sends native tokens back using sendValue()
• _reward(account, amount) - Mints rewards via the Native Minter precompile at 0x0200000000000000000000000000000000000001

Reward Distribution

Staking rewards are minted through the Native Minter precompile, which requires the NativeTokenStakingManager contract address to be added as an Enabled address. This grants the contract permission to mint new native tokens as rewards.

ERC20TokenStakingManager

ERC20TokenStakingManager exists because native tokens cannot be used with the payable keyword on all blockchains. Some chains may want to use a separate ERC20 token for staking instead of their native token.

Why a Separate Implementation?

The key difference is in the function signatures:

• NativeTokenStakingManager: initiateValidatorRegistration(...) payable - receives native tokens via msg.value
• ERC20TokenStakingManager: initiateValidatorRegistration(..., uint256 stakeAmount) - requires explicit stakeAmount parameter

How It Works

• Stores a reference to an ERC20 token that implements IERC20Mintable
• Requires token approval before staking
• Uses safeTransferFrom() to lock tokens during registration
• Uses safeTransfer() to unlock tokens during removal
• Mints new ERC20 tokens as rewards