Device Management Kit

The device management kit is the entry point for all the other libraries related to it. As we wanted to make the project modular.

Main Features

• Discovering and connecting to Ledger devices via USB, through WebHID.
• Discovering and connecting to Ledger devices via BLE, through WebBLE.
• Observing the state of a connected device.
• Sending custom APDU commands to Ledger devices.
• Sending a set of pre-defined commands to Ledger devices.
  • Get OS version
  • Get app and version
  • Open app
  • Close app
  • Get battery status
• Execute a flow of commands with DeviceAction.

[!NOTE]
At the moment we do not provide the possibility to distinguish two devices of the same model, via WebHID and to avoid connection to the same device twice.

Communicate with a Ledger device

The DMK is offering several ways to communicate with a Ledger device.

Send APDU

You can send APDU commands to the device using the sendApdu method of the Device Management Kit instance (here dmk) instance.

Parameters:

• sessionId: string - The session ID, identifier of the connection with a device.
• apdu: UInt8Array - bytes array of data to be send to the device.

await dmk.sendApdu({ sessionId, apdu });

Commands

Commands are pre-defined actions that you can send to the device. You can use the sendCommand method of the dmk instance to send a command to the device.

Parameters:

• sessionId: string - The session ID, which an identifier of the connection with a device.
• command: Command - The command to be sent to the device.

import { OpenAppCommand } from "@ledgerhq/device-management-kit";
 
const command = new OpenAppCommand("Bitcoin"); // Open the Bitcoin app
await dmk.sendCommand({ sessionId, command });

Device Actions

Device actions are a set of commands that are executed in a sequence. You can use the executeDeviceAction method of the dmk instance to execute a device action.

It is returning an observable that will emit different states of the action execution. A device action is cancellable, you can cancel it by calling the cancel function returned by the executeDeviceAction method.

Parameters:

• sessionId: string - The session ID, which an identifier of the connection with a device.
• deviceAction: DeviceAction - The DeviceAction to be sent to the device.

const openAppDeviceAction = new OpenAppDeviceAction({ appName: "Bitcoin" });
 
const { observable, cancel } = await dmk.executeDeviceAction({
  sessionId,
  openAppDeviceAction,
});

State Management

For each connected device, we are managing and providing a device state.

The different states are:

• connected: The device is connected.
• locked: The device is locked. User needs to unlock it to perform operations.
• busy: The device is busy, so not reachable.
• disconnected: The device is disconnected.