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

# ERC-1271 signatures

> Enable ERC-1271 compatible signatures for smart contract wallets and off-chain verifiers

[ERC-1271](https://eips.ethereum.org/EIPS/eip-1271) is a standard interface that allows smart contracts to verify signatures on behalf of an address. When a Privy embedded wallet is upgraded to a smart contract wallet — via [EIP-7702](/wallets/using-wallets/ethereum/sign-7702-authorization) or Privy's [gas sponsorship](/wallets/gas-and-asset-management/gas/setup) — the wallet address has contract code. Some smart contracts and off-chain verifiers check signatures by calling the ERC-1271 `isValidSignature` method on the wallet address instead of using `ecrecover`.

To ensure your signatures are verifiable by these ERC-1271 aware systems, Privy supports an `erc1271` signature mode.

<Info>
  ERC-1271 signature mode is only needed when your wallet is an EIP-7702 delegated smart contract
  wallet, such as when using Privy's gas sponsorship. Standard embedded wallets (EOAs) do not need
  this mode.
</Info>

## When to use ERC-1271 signatures

Use ERC-1271 signatures when **all** of the following are true:

* Your wallet uses [gas sponsorship](/wallets/gas-and-asset-management/gas/setup) or is otherwise delegated via EIP-7702
* A smart contract or off-chain service verifies signatures using the ERC-1271 `isValidSignature` interface

Common use cases include:

* **DeFi protocols** that support both EOA and smart account signers
* **Off-chain payment authorization** (e.g. [x402 payments](/recipes/agent-integrations/x402) with gas-sponsored wallets)
* **SIWE (Sign-In With Ethereum)** with smart contract wallets
* Any integration where the verifier calls `IERC1271.isValidSignature` on the signer address

## Producing ERC-1271 signatures

Privy exposes ERC-1271 signing through the `signatureOptions: {type: 'erc1271'}` option on signing methods.

Pass `signatureOptions: {type: 'erc1271'}` to signing methods when the wallet is gas-sponsored or EIP-7702 delegated.

### Signing a message

```typescript theme={"system"}
import {PrivyClient} from '@privy-io/node';

const privy = new PrivyClient({appId, appSecret});

const {signature} = await privy
  .wallets()
  .ethereum()
  .signMessage('your-wallet-id', {
    message: 'I authorize this action',
    signatureOptions: {type: 'erc1271'}
  });
```

### Signing typed data (EIP-712)

```typescript theme={"system"}
import {PrivyClient} from '@privy-io/node';

const privy = new PrivyClient({appId, appSecret});

const {signature} = await privy
  .wallets()
  .ethereum()
  .signTypedData('your-wallet-id', {
    params: {
      typed_data: {
        domain: {
          name: 'My App',
          version: '1',
          chainId: 1,
          verifyingContract: '<your-verifying-contract-address>'
        },
        types: {
          Order: [
            {name: 'amount', type: 'uint256'},
            {name: 'deadline', type: 'uint256'}
          ]
        },
        primary_type: 'Order',
        message: {
          amount: '1000000',
          deadline: '1893456000'
        }
      }
    },
    signatureOptions: {type: 'erc1271'}
  });
```

## How it works

When a Privy embedded wallet is upgraded via EIP-7702 (either through gas sponsorship or a direct delegation), the wallet address has smart contract bytecode. The delegated smart contract implements `isValidSignature(bytes32 hash, bytes signature)`, which validates that the underlying EOA's private key produced the signature.

Privy's `erc1271` signature mode produces signatures in the exact format that the delegated smart contract's `isValidSignature` implementation expects. Without this mode, the raw ECDSA signature bytes may not match the format the smart contract validates, causing verification to fail.