# Vote By Signature

The `castVoteBySig` function allows an offline signer to participate in Onyx governance voting by submitting a digitally signed vote. Unlike the castVote function, which requires the voter to be online and execute the transaction, this function enables voting via an EIP-712-compliant signature, making it useful for delegated and gasless voting.

### Function Implementation in `CHNGovernance`

The `castVoteBySig()` function ensures that votes can be cast securely and efficiently using off-chain signatures, reducing the need for direct blockchain interaction while maintaining the integrity of the voting process.

#### Function Signature

```
function castVoteBySig(
    uint proposalId,
    bool support,
    uint8 v,
    bytes32 r,
    bytes32 s
) public
```

**Parameters**

* `proposalId`: The unique identifier of the governance proposal on which the vote is being cast.
* `support`: A boolean value indicating the vote choice:
  * true → Vote in favor of the proposal (Yes)
  * false → Vote against the proposal (No)
* `v`: The recovery byte of the signature, used for ECDSA signature verification.
* `r`: First half of the ECDSA signature pair.
* `s`: Second half of the ECDSA signature pair.
* `RETURN:`The function does not return a value. If the proposal ID is invalid or the signature is not valid, the transaction reverts with an error.

#### Example Solidity Implementation

To cast a vote using Solidity, the `castVoteBySig()` function can be called from an instance of the `CHNGovernance` contract:

{% code overflow="wrap" %}

```
CHNGovernance gov = CHNGovernance(0x123...); // Contract address of CHNGovernance
gov.castVoteBySig(proposalId, true, v, r, s); // Voting in favor using an offline signature
```

{% endcode %}

#### Web3.js Implementation (v1.2.6)

For interacting with the `CHNGovernance` contract using Web3.js, the following example demonstrates how to cast a vote by signature:

{% code overflow="wrap" %}

```javascript
const tx = await gov.methods.castVoteBySig(proposalId, false, v, r, s).send({}); // Voting against using an offline signature
```

{% endcode %}

#### Technical Considerations

* The `castVoteBySig()` function is state-modifying and will incur gas costs.
* Votes are weighted based on the voting power at the moment the proposal became Active.
* EIP-712-compliant signatures ensure the security and authenticity of the vote.
* If the signature is invalid or does not match the voter's address, the transaction reverts with an error.
* This function allows users to sign a vote offline and have another address submit the vote on-chain, enabling gasless voting if subsidized by a third party.
* Governance interfaces and voting dashboards should support offline signing workflows to increase accessibility and voter participation.