Building a Live App: A Step-by-Step Tutorial - Ledger

Introduction

Ledger provides APIs and SDKs to integrate hardware wallet functionalities into live applications. This tutorial walks you through creating a secure, live crypto app connected to Ledger devices.

Step 1: Environment Setup

• Install Node.js and npm on your development machine.
• Create a new project folder and initialize it with npm init.
• Install Ledger SDK packages: npm install @ledgerhq/hw-app-eth @ledgerhq/hw-transport-node-hid.

Step 2: Connect to Ledger Device

• Import the transport and app classes:

const TransportNodeHid = require('@ledgerhq/hw-transport-node-hid').default;
const AppEth = require('@ledgerhq/hw-app-eth').default;

• Open a connection to your Ledger device:

const transport = await TransportNodeHid.create();
const eth = new AppEth(transport);

Step 3: Fetch Public Key and Address

Retrieve Ethereum addresses securely:

const result = await eth.getAddress("44'/60'/0'/0/0");
console.log(result.address);

Step 4: Transaction Signing

• Prepare transaction data according to Ethereum specifications.
• Request signature from Ledger device:

const signature = await eth.signTransaction("44'/60'/0'/0/0", txHex);

• Broadcast the signed transaction to the network securely.

Step 5: Integrating into Live App

• Integrate Ledger connection logic into your frontend or backend.
• Use transport events to detect device connection and disconnection.
• Ensure all sensitive operations occur on-device, never exposing private keys.

Step 6: Security Best Practices

• Always validate user input before sending to Ledger.
• Confirm transaction details on the Ledger device screen.
• Keep Ledger firmware and SDKs up-to-date.
• Never store private keys in code or environment variables.

FAQs

Q: Can I connect multiple Ledger devices simultaneously?
A: Yes, by opening separate transport connections for each device.

Q: Is it safe to use Ledger SDK in production?
A: Yes, as long as all sensitive operations remain on-device and SDKs are up-to-date.