Communicate with smartcard reader through Android USB host

Communicating with Smartcard Reader Through Android USB Host

This article will guide you through the process of establishing communication between a smartcard reader and your Android device using USB Host mode.

Introduction

Android’s USB Host mode allows devices to act as a host, controlling peripherals like smartcard readers. This empowers developers to create applications that leverage smartcard functionality.

Prerequisites

• Android device with USB Host support.
• Smartcard reader compatible with USB HID (Human Interface Device) protocol.
• Android Studio (or a suitable IDE) with the Android SDK installed.
• Knowledge of Java programming and Android development concepts.

Understanding USB HID Communication

The USB HID protocol defines a standardized way for devices like keyboards, mice, and smartcard readers to communicate with computers. For smartcard readers, this protocol involves:

• Input Reports: Data received from the smartcard reader.
• Output Reports: Commands sent to the smartcard reader.

Steps to Communicate with a Smartcard Reader

1. Permission Setup

In your AndroidManifest.xml, ensure the following permissions are declared:

<uses-permission android:name="android.permission.ACCESS_USB_PERMISSION" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2. USB Device Detection

Utilize the UsbManager class to monitor USB device connection events. Use the following code to find and connect to the smartcard reader:

UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
UsbDevice device = usbManager.getDeviceList().values().iterator().next();
if (device != null) {
  // Connect to the device
  PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent("com.example.app.USB_PERMISSION"), 0);
  usbManager.requestPermission(device, permissionIntent);
} else {
  // Device not found
}

3. Opening a USB Connection

Once the device is found and permission is granted, open a USB connection using UsbDeviceConnection.

UsbDeviceConnection connection = usbManager.openDevice(device);
if (connection != null) {
  // Communication setup
} else {
  // Failed to open connection
}

4. Communication Setup

After opening the connection, you need to set up communication with the smartcard reader. This involves:

• Endpoint Identification: Determine the input and output endpoints for the device using the device descriptor.
• Data Transfer: Utilize the UsbDeviceConnection’s bulkTransfer() method for data transfer between endpoints.

5. Sending Commands and Receiving Responses

Formulate commands according to the smartcard reader’s specifications and send them using bulkTransfer() for the output endpoint. Then, receive responses using bulkTransfer() for the input endpoint. You can then process the received data.

Code Example

// Function to send a command to the smartcard reader
private boolean sendCommand(byte[] command) {
  int result = connection.bulkTransfer(outputEndpoint, command, command.length, 1000);
  return result >= 0;
}

// Function to receive a response from the smartcard reader
private byte[] receiveResponse(int length) {
  byte[] response = new byte[length];
  int result = connection.bulkTransfer(inputEndpoint, response, response.length, 1000);
  if (result >= 0) {
    return response;
  } else {
    return null;
  }
}

Example Scenario: Reading a Smartcard

1. Send a command to the smartcard reader to select a specific card.
2. Receive a response indicating success or failure.
3. If successful, send a command to read data from the card.
4. Receive the card data as a response.

Security Considerations

• Sensitive Data Protection: Never transmit sensitive information over an unencrypted USB connection.
• Authentication: Implement proper authentication mechanisms to prevent unauthorized access.

Table Comparison

Conclusion

This article provided a comprehensive guide to communicating with a smartcard reader through Android USB Host mode. By following these steps and adhering to security considerations, you can successfully develop applications that utilize smartcard functionality on Android devices.