WhitelistStaking

A single-file Solidity smart contract that provides a dynamic whitelist based on native ETH staking. No imports and no constructor parameters — fully self-contained.

Key ideas

• Users stake native ETH (via stake() or by sending ETH directly) to accumulate balance in the contract.

• If a user's stake is ≥ stakeRequirement, they become automatically whitelisted.

• If they withdraw and their stake falls below the requirement, they are removed from the whitelist.

• The owner (deployer) can change the stake requirement and perform batch updates or manual whitelist overrides.

• Reentrancy guard included (simple, internal).

Files

• WhitelistStaking.sol — the Solidity contract (single file; no imports; no constructor).

Deployment

• Solidity compiler version: ^0.8.20.

• There is no constructor. Owner is set to the deployer (the address that sends the transaction creating the contract).

• Deploy normally using your preferred tooling (Hardhat, Remix, Foundry, etc).

Important public functions

• stake() — payable. Stake ETH (adds msg.value to caller's stake; auto-whitelists if stake ≥ requirement).

• withdraw(uint256 amount) — withdraw part/all of your stake (ETH returned to caller). If resulting stake < requirement, auto-removes from whitelist.

• ownerCreditStake(address user) — payable owner function to credit a user's stake from owner funds.

• isWhitelisted(address account) — view: returns boolean.

• getStake(address account) — view: returns stake in wei.

• setStakeRequirement(uint256 newRequirement) — owner-only: change required stake (in wei).

• batchUpdateWhitelist(address[] calldata addrs) — owner-only: evaluate a list of addresses and add/remove them based on current stakes.

• ownerSetWhitelist(address account, bool status) — owner-only: manually override whitelist status.

• transferOwnership(address newOwner) — owner-only.

• emergencyWithdraw(address payable to, uint256 amount) — owner-only emergency ETH withdraw from contract balance (use with caution).

Also supports receive() and fallback() to treat direct ETH transfers as stakes.

Events

• StakeDeposited(address user, uint256 amount)

• StakeWithdrawn(address user, uint256 amount)

• Whitelisted(address user)

• Dewhitelisted(address user)

• StakeRequirementChanged(uint256 oldRequirement, uint256 newRequirement)

• OwnerTransferred(address oldOwner, address newOwner)

• EmergencyWithdraw(address to, uint256 amount)

Example usage

1. Deploy contract (deployer becomes owner).

2. Users:

   • Call stake() with msg.value (e.g. 1 ether) → if stake ≥ requirement they'll be whitelisted.

   • Or send ETH directly to contract address → same effect (receive/fallback treat it as stake).

3. Users can call withdraw(amount) to take out ETH; if lowered below requirement they will be dewhitelisted automatically.

4. Owner can change stakeRequirement (e.g. to increase minimum), and then call batchUpdateWhitelist with a list of addresses to immediately enforce the new rule.

Security notes & recommendations

• Native ETH only: This contract uses native ETH for staking. If you prefer ERC-20 token staking, the contract must be expanded (adds ERC-20 transfer/approve handling) — that would require adding interface code (still doable without imports).

• EmergencyWithdraw: Owner can withdraw ETH from the contract with emergencyWithdraw. This withdraws from contract balance and may include staked funds (use with extreme caution). You could disable this in a production release or add clearer separation between user stakes and operational funds.

• No builtin rewards: This contract does not pay interest or rewards—just tracks stakes.

• Batch operations cost gas: batchUpdateWhitelist iterates; keep arrays modest to avoid hitting block gas limits.

• Reentrancy guard: Implemented for deposit/withdrawal flows.

• Owner powers: Owner can manually set/clear whitelist entries. Consider multisig ownership or governance for production.

• Testing: Thoroughly test staking/withdraw and edge cases (e.g. partial withdraws that exactly meet requirement, direct sends, fallback behaviour).

Possible improvements

• Add explicit separation of user-staked funds vs. protocol funds (escrow pattern).

• Add ERC-20 staking option.

• Add on-chain snapshotting / event logs that index whitelisted users.

• Add a timelock or multisig for owner actions (transferOwnership, setStakeRequirement, emergencyWithdraw).

• Add feature to lock stake for a duration (to prevent flash stake/un-stake to manipulate access).

Example values

• Default stakeRequirement = 1 ether at deployment. Owner can change it.