# EVM Contract Types

This page documents the data types used in the Signet EVM Contract.

## SignRequest

Request structure for initiating a signature via [`sign`](/contract-api/evm/functions#sign).

```solidity
struct SignRequest {
    bytes32 payload;
    string path;
    uint32 keyVersion;
    string algo;
    string dest;
    string params;
}
```

### Fields

| Field        | Type      | Description                                      |
| ------------ | --------- | ------------------------------------------------ |
| `payload`    | `bytes32` | 32-byte data to be signed (typically a hash)     |
| `path`       | `string`  | Derivation path for the signing key              |
| `keyVersion` | `uint32`  | Version of the MPC key to use                    |
| `algo`       | `string`  | Signing algorithm (optional, default: secp256k1) |
| `dest`       | `string`  | Response destination chain (optional)            |
| `params`     | `string`  | Additional parameters as JSON (optional)         |

## Response

Response structure containing a signature for a request.

```solidity
struct Response {
    bytes32 requestId;
    Signature signature;
}
```

### Fields

| Field       | Type                      | Description                        |
| ----------- | ------------------------- | ---------------------------------- |
| `requestId` | `bytes32`                 | Identifier of the original request |
| `signature` | [`Signature`](#signature) | ECDSA signature for the request    |

## Signature

ECDSA signature structure returned by the MPC network.

```solidity
struct Signature {
    AffinePoint bigR;
    uint256 s;
    uint8 recoveryId;
}
```

### Fields

| Field        | Type                          | Description                                  |
| ------------ | ----------------------------- | -------------------------------------------- |
| `bigR`       | [`AffinePoint`](#affinepoint) | R point of the ECDSA signature               |
| `s`          | `uint256`                     | s scalar of the signature                    |
| `recoveryId` | `uint8`                       | Recovery ID for public key recovery (0 or 1) |

## AffinePoint

Represents a point on the secp256k1 elliptic curve.

```solidity
struct AffinePoint {
    uint256 x;
    uint256 y;
}
```

### Fields

| Field | Type      | Description               |
| ----- | --------- | ------------------------- |
| `x`   | `uint256` | x coordinate of the point |
| `y`   | `uint256` | y coordinate of the point |

### Notes

* For the signature's R point, `x` is typically used as the `r` value in RSV format