Message Signing

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Overview

Message signing allows you to apply a unique cryptographic signature to verify your identity on EVM networks.

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 a message using EIP-712 structured data

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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 from "dotenv";  
  
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 Wallet API 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.

Here is a complete example showing how to sign EIP-712 typed data:

import { CdpClient } from "@coinbase/cdp-sdk";  
  
import dotenv from "dotenv";  
  
dotenv.config();  
  
const cdp = new CdpClient();  
  
// Create EVM account  
const account = await cdp.evm.createAccount();  
console.log("Created account:", account.address);  
  
// Sign typed data  
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:

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What to read next

• v2 Security: Learn about the security features of v2 Wallet API.
• API Reference: Explore the complete API reference for v2 Wallet API.