EIP712StETH
EIP712StETH
serves as a dedicated helper contract for stETH
, crucial for complete support of ERC-2612 compliant signed approvals.
Why This Helper Is Needed
The original Lido/StETH
contract is implemented in Solidity 0.4.24
, while this helper is implemented in Solidity 0.8.9
. The newer compiler version enables access to the current network's chain id via the globally available variable block.chainid
. The chain id is mandatory for signature inclusion as per EIP-155 to prevent replay attacks, wherein an attacker intercepts a valid network transmission and then rebroadcasts it on another network fork. Consequently, EIP-155
compliance is critical for securing ERC-2612
signed approvals.
View Methods
domainSeparatorV4()
This method returns the EIP712
-compatible hashed domain separator, which is valid for stETH
token permit signatures. The domain separator is essential in preventing a signature intended for one dApp from functioning in another (thereby averting a signature collision in a broader sense).
function domainSeparatorV4(address _stETH) returns (bytes32)
Also, consider the eip712Domain()
method that can construct a domain separator from StETH
-specific fields on the client's side, such as within a dApp or a wallet. For instance, Metamask relies on eth_signTypedData_v4
, which requires a non-hashed domain separator being provided.
hashTypedDataV4()
This method returns the hash of a fully encoded EIP712
-compatible message for this domain. The method can validate the input data against the provided v, r, s
secp256k1 components.
function hashTypedDataV4(address _stETH, bytes32 _structHash) returns (bytes32)
Parameters
Name | Type | Description |
---|---|---|
_stETH | address | Address of the deployed stETH token |
_structHash | bytes32 | Hash of the data structure |
For a specific use case, see the StETHPermit.permit() implementation.
eip712Domain()
This method returns the fields and values necessary to construct a domain separator on the client's side. The method resembles the one proposed in ERC-5267, with the only difference being that it doesn't return unused fields.
function eip712Domain(address _stETH) returns (
string memory name,
string memory version,
uint256 chainId,
address verifyingContract
)
Parameters
Name | Type | Description |
---|---|---|
_stETH | address | Address of the deployed stETH token |
Returns
Name | Type | Description |
---|---|---|
name | string | Name of the token |
version | string | Version of the token |
chainId | uint256 | Chain identifier |
verifyingContract | address | Address of the token contract |
Provided the correct _stETH
deployed address, it returns:
- ("Liquid staked Ether 2.0", "2", 1, 0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84) for Mainnet.
- ("Liquid staked Ether 2.0", "2", 5, 0x1643E812aE58766192Cf7D2Cf9567dF2C37e9B7F) for Görli.
This method facilitates domain separator construction on the client's side, such as in a wallet or widget:
function makeDomainSeparator(name, version, chainId, verifyingContract) {
return web3.utils.keccak256(
web3.eth.abi.encodeParameters(
['bytes32', 'bytes32', 'bytes32', 'uint256', 'address'],
[
web3.utils.keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
web3.utils.keccak256(name),
web3.utils.keccak256(version),
chainId,
verifyingContract,
]
)
)
}