Sign typed data

This guide will teach you how to sign EIP-712 typed data with your Smart Wallet. Typed data signing provides a more structured and secure way to sign complex data compared to plain text messages.

Prerequisites

• API key from your dashboard
• A Smart Wallet with an associated signer

What is typed data signing?

EIP-712 typed data signing allows users to:

• Sign structured data with clear type definitions
• Improve user experience with readable signature requests
• Enhance security through type safety and domain separation

Typed data follows the EIP-712 standard, which provides a way to encode structured data for signing.

Implementation

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import { client, signer } from "./client";
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const signerAddress = await signer.getAddress();
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// Sign typed data
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const typedData = {
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  domain: {
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    name: "MyDApp",
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    version: "1",
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    chainId: 1,
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    verifyingContract: "0x...",
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  },
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  types: {
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    Auth: [
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      { name: "user", type: "address" },
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      { name: "nonce", type: "uint256" },
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      { name: "timestamp", type: "uint256" },
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    ],
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  },
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  primaryType: "Auth",
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  message: {
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    user: signerAddress,
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    nonce: 12345,
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    timestamp: Date.now(),
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  },
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} as const;
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const signature = await client.signTypedData({
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  ...typedData,
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  account: signerAddress,
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});
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console.log("Typed data signature:", signature);

Typed data structure

EIP-712 typed data consists of four main components:

Domain

The domain provides context and prevents signature reuse across different dApps:

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const domain = {
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  name: "Example DApp",
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  version: "1",
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  chainId: 1,
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  verifyingContract: "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
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};

Types

Define the structure of your data:

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const types = {
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  Person: [
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    { name: "name", type: "string" },
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    { name: "wallet", type: "address" },
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  ],
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  Mail: [
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    { name: "from", type: "Person" },
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    { name: "to", type: "Person" },
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    { name: "contents", type: "string" },
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  ],
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};

Primary type

Specify which type is the main type being signed:

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const primaryType = "Mail";

Message

The actual data to sign:

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const message = {
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  from: {
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    name: "Alice",
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    wallet: "0xAaAaAaAaAaAaAaAaAaAAAAAAAAaaaAaAaAaaAaAa",
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  },
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  to: {
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    name: "Bob",
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    wallet: "0xBbBbBbBbBbBbBbBbBbBBBBBBBBbbBbBbBbbBbBb",
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  },
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  contents: "Hello, Bob!",
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};

Next steps

Build more:

• Sign messages
• Send transactions

Troubleshooting:

• Common errors