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Overview

EIP-712 message signing allows you to sign structured data using a human-readable format. Using the CDP-SDK, developers can enable signing while presenting clear, meaningful messages to users, rather than unintelligible raw hexadecimal hashes. In this guide, you will learn how to:
  • Create an EVM account
  • Sign an EIP-712 message

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Prerequisites

It is assumed you have already completed the Quickstart guide.

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1. Create an account

To create an account, see below: 
import { CdpClient } from "@coinbase/cdp-sdk";  
import "dotenv/config";  
  
const cdp = new CdpClient();  
  
const account = await cdp.evm.createAccount();  
  
console.log("Successfully created account: ", account.address);
After running the above snippet, you should see output similar to the following: 
Successfully created account: 0x6aAEc7535706ce8B36ea184B2236D53702c1F06A

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2. Sign message

The v2 Server Wallet supports EIP-712 for typed structured data hashing and signing, providing a way to create human-readable messages that can be signed and verified onchain.

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Domain Separator

The domain separator is a unique identifier for the application or protocol. It helps prevent signature collisions between different applications.It typically includes:
  • name: the name of the application (e.g., “MyApp”)
  • chainId: the network ID where the signature will be verified (e.g., 1 for Ethereum mainnet)
  • verifyingContract: the address of the contract that will verify the signature

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Type Definitions

Type definitions describe the structure of your message. They include the required EIP712Domain type and your custom types. Each custom type is defined as an array of fields, where each field has a name and type.
  • EIP712Domain: required base type that defines the domain structure
    • name (string)
    • version (string)
    • chainId (uint256)
    • verifyingContract (address)
    • salt (bytes32)
  • Custom Types: your application-specific types (e.g., “Person”)
    • Each field has a name and type
    • Can include nested types
    • Must be properly defined before use

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Primary Type

The primary type is the main type of the message you’re signing. It should be one of the types defined in your type definitions.

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Message

The message contains the actual data you want to sign. It must match the structure defined by your primary type.
Here is a complete example showing how to sign EIP-712 typed data: 
import { CdpClient } from "@coinbase/cdp-sdk";
import "dotenv/config";
  
const cdp = new CdpClient();
  
const account = await cdp.evm.createAccount();
console.log("Created account:", account.address);
  
const signature = await cdp.evm.signTypedData({
  address: account.address,
  domain: {
    name: "MyApp",
    chainId: 1,
    verifyingContract: "0x0000000000000000000000000000000000000000",
  },
  types: {
    EIP712Domain: [
      { name: "name", type: "string" },
      { name: "chainId", type: "uint256" },
      { name: "verifyingContract", type: "address" },
    ],
    Person: [
      { name: "name", type: "string" },
      { name: "age", type: "uint256" }
    ]
  },
  primaryType: "Person",
  message: {
    name: "Alice",
    age: 25
  },
});

console.log("Signature:", signature);
After running the above snippet, you should see output similar to the following: 
Created account: 0x2Ae896e791c9596c7beDeCC3E06Fa6DA9aE2B193  
Signature:  0xa8fdc11edcf120b116d34131159ca356af52b90732425ebec48cac125a449e7d2151d97ca8232bff43568da9ee2249cf1bc187c392f1d1e53c72fc0b5937f5b31b
To summarize, in the example above, we:
  • Created an EVM account
  • Signed a message using EIP-712 structured data, which includes: a domain separator, type definitions, primary type, and a message payload (a person named Alice who is 25 years old)
The EIP-712 structured data was used to create a human-readable message which we successfully signed cryptographically.

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Video: Watch and learn

Watch this video for a walkthrough of EIP-712 message signing:
  • v2 Security: Learn about the security features of v2 Server Wallet.
  • API Reference: Explore the complete API reference for v2 Server Wallet.
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