> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cow.bleu.builders/llms.txt
> Use this file to discover all available pages before exploring further.

# Signing

> Signing mechanisms for CoW Protocol orders with multiple scheme support

# Signing

CoW Protocol supports four distinct signing approaches for order authorization.

## Signing Schemes

```typescript theme={null}
enum SigningScheme {
  EIP712 = 0,   // Structured data signing (recommended)
  ETHSIGN = 1,  // Legacy eth_sign RPC
  EIP1271 = 2,  // Smart contract signatures
  PRESIGN = 3,  // On-chain pre-approval
}
```

### EIP-712 (Recommended)

Shows users a structured representation of the order data in their wallet, making it clear what they are signing.

```typescript theme={null}
const signature = await signOrder(
  settlementDomain,
  order,
  wallet,
  SigningScheme.EIP712
);
```

### EthSign

Available for legacy wallet compatibility but provides minimal context to users about transaction details.

```typescript theme={null}
const signature = await signOrder(
  settlementDomain,
  order,
  wallet,
  SigningScheme.ETHSIGN
);
```

### EIP-1271

For smart contract wallets like multi-signature systems. Enables verification through contract-based signature validation.

```typescript theme={null}
const eip1271Sig: Eip1271Signature = {
  scheme: SigningScheme.EIP1271,
  verifier: safeAddress,
  data: signatureBytes,
};

const encoded = encodeEip1271SignatureData(eip1271Sig);
```

### PreSign

Orders approved directly on-chain by calling `setPreSignature` on the settlement contract.

```typescript theme={null}
const preSignSig: PreSignSignature = {
  scheme: SigningScheme.PRESIGN,
  signer: ownerAddress,
};
```

## Signature Types

### EcdsaSignature

```typescript theme={null}
interface EcdsaSignature {
  scheme: SigningScheme.EIP712 | SigningScheme.ETHSIGN;
  data: string; // r, s, v values
}
```

### Eip1271Signature

```typescript theme={null}
interface Eip1271Signature {
  scheme: SigningScheme.EIP1271;
  verifier: string;
  data: string;
}
```

### PreSignSignature

```typescript theme={null}
interface PreSignSignature {
  scheme: SigningScheme.PRESIGN;
  signer: string;
}
```

## Core Functions

### signOrder

```typescript theme={null}
async function signOrder(
  domain: TypedDataDomain,
  order: Order,
  signer: Signer,
  scheme: SigningScheme.EIP712 | SigningScheme.ETHSIGN
): Promise<EcdsaSignature>;
```

### encodeEip1271SignatureData

```typescript theme={null}
function encodeEip1271SignatureData(signature: {
  verifier: string;
  data: string;
}): string;
```

### decodeEip1271SignatureData

```typescript theme={null}
function decodeEip1271SignatureData(encoded: string): {
  verifier: string;
  data: string;
};
```

<Tip>
  Always use the correct domain with appropriate chain IDs and settlement contract addresses to prevent replay attacks across different networks.
</Tip>