Entities and stake

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Entities

Mempool rules are applied per entity: the sender, the payer and the factory of a transaction. Reputation is tracked per entity address, not per role.

A default-code entity is an entity whose account has no code and so runs EIP-8141’s default code. It has no bytecode to trace, is never staked, and is exempt from the opcode, call and storage rules.

What stake buys

Staking is a Sybil defence. Creating an entity is free, so the mempool needs an economic cost for creating an abusive one. A staked entity gets a wider set of permissions:

Permission	Rule
A higher validation gas budget	BUDGET-010
BALANCE and SELFBALANCE opcodes	OPCODES-010
Access to its own storage	STORAGE-031
Read-only access to any storage in a contract that is not an entity of the transaction	STORAGE-032
Write access to slots associated with its address, in any contract that is not an entity of the transaction	STORAGE-033
Factory access to the sender’s associated storage in a deploying transaction	STORAGE-022
No sender-wide pending limit while ACTIVE	LIFECYCLE-030
No cap on pending transactions while ACTIVE	REPUTATION

The stake is never slashed

There are no penalty mechanisms in the Alternative Mempools protocol. The significant lock-up period is the cost of creating a new abusive entity.

Definition of staked

STAKING-010: an entity is staked if the Staking Registry reports a stake of at least MIN_STAKE_VALUE and an unstake delay of at least MIN_UNSTAKE_DELAY, and withdrawal has not been initiated.

• MIN_STAKE_VALUE is per chain. It is roughly the equivalent of USD 1000 in the native token.
• MIN_UNSTAKE_DELAY is 86400 seconds, one day.

Calling unlockStake() starts a withdrawal. From that moment the entity is no longer considered staked, even though the funds stay in the registry until withdrawStake is called.

The Staking Registry

Stake lives in a dedicated contract at STAKING_REGISTRY_ADDRESS. It implements:

interface IStakingRegistry {
    /// Lock `msg.value` as the caller's stake, with the given unstake delay.
    function addStake(uint32 unstakeDelaySec) external payable;

    /// Begin the withdrawal delay. From this point the caller is not considered to be staked.
    function unlockStake() external;

    /// Withdraw the stake after the delay has passed.
    function withdrawStake(address payable withdrawAddress) external;

    /// Return the stake information.
    function getDepositInfo(address account)
        external
        view
        returns (uint256 stake, uint32 unstakeDelaySec, uint64 withdrawTime);
}

The registry keys everything off msg.sender. A contract entity such as a paymaster or factory must call addStake itself, so it needs code that forwards a call to the registry. See Staking an entity.

Security note

The stake provisions depend on a registry contract outside the EIP-8141 protocol. The correctness of the deployed registry is critical for the security of the whole Alternative Mempool system.