Implementing OAuth2 Device Code Flow with Spring Boot and Spring Security

Hello, Spring enthusiasts! 👋 Today, we’re going to explore how to implement an OAuth2 Device Code Flow using Spring Boot and Spring Security. This flow is particularly useful for devices with limited input capabilities, such as smart TVs, IoT devices, and other consumer electronics.

Understanding the OAuth2 Device Code Flow

The OAuth2 Device Code Flow allows users to authorize devices with limited input capabilities. The device requests a device code and user code from the authorization server, which the user then enters on a separate device with a full browser. Once the user authorizes the device, the device can exchange the device code for an access token.

Steps to Implement the Device Code Flow

Set Up the Spring Boot Project: Start by creating a new Spring Boot project with the necessary dependencies.
Configure Security: Set up Spring Security to handle OAuth2 authentication and authorization.
Create the Device Authorization Endpoint: Implement the endpoint to handle device authorization requests.
Create the Device Token Endpoint: Implement the endpoint to handle token requests using the device code.
Handle Device Authorization Logic: Write the logic to generate and validate device codes and user codes.
Test the Flow: Ensure the flow works correctly by testing it with various devices.

Step 1: Set Up the Spring Boot Project

First, create a new Spring Boot project using Spring Initializr or your favorite IDE. Add the following dependencies:

Spring Web
Spring Security
Spring Security OAuth2 Resource Server
Spring Security OAuth2 Authorization Server

Step 2: Configure Security

In your application.yml or application.properties, configure the security settings:


spring:
  security:
    oauth2:
      authorizationserver:
        issuer-uri: https://your-issuer-uri

Step 3: Create the Device Authorization Endpoint

Create a new controller to handle the device authorization requests:


import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DeviceAuthorizationController {

    @PostMapping("/oauth2/device_authorization")
    public DeviceAuthorizationResponse authorizeDevice(@RequestBody DeviceAuthorizationRequest request) {
        // Implement device authorization logic here
        return new DeviceAuthorizationResponse(deviceCode, userCode, verificationUri, expiresIn);
    }
}

Step 4: Create the Device Token Endpoint

Create a new controller to handle the token requests using the device code:


import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DeviceTokenController {

    @PostMapping("/oauth2/device_token")
    public TokenResponse exchangeDeviceCode(@RequestBody DeviceTokenRequest request) {
        // Implement device token exchange logic here
        return new TokenResponse(accessToken, refreshToken, expiresIn);
    }
}

Step 5: Handle Device Authorization Logic

Implement the logic to generate and validate device codes and user codes:


import org.springframework.stereotype.Service;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;

@Service
public class DeviceAuthorizationService {

    private final ConcurrentHashMap deviceAuthorizationStore = new ConcurrentHashMap<>();

    public DeviceAuthorizationResponse authorizeDevice(String clientId) {
        String deviceCode = generateDeviceCode();
        String userCode = generateUserCode();
        String verificationUri = "https://your-issuer-uri/device";
        long expiresIn = TimeUnit.MINUTES.toSeconds(10);

        deviceAuthorizationStore.put(deviceCode, new DeviceAuthorization(clientId, userCode, expiresIn));

        return new DeviceAuthorizationResponse(deviceCode, userCode, verificationUri, expiresIn);
    }

    public TokenResponse exchangeDeviceCode(String deviceCode) {
        DeviceAuthorization authorization = deviceAuthorizationStore.get(deviceCode);
        if (authorization != null && !authorization.isExpired()) {
            // Generate access token and refresh token
            String accessToken = generateAccessToken();
            String refreshToken = generateRefreshToken();
            long expiresIn = TimeUnit.HOURS.toSeconds(1);

            return new TokenResponse(accessToken, refreshToken, expiresIn);
        } else {
            throw new InvalidDeviceCodeException("Invalid or expired device code");
        }
    }

    private String generateDeviceCode() {
        // Implement device code generation logic
        return "generated-device-code";
    }

    private String generateUserCode() {
        // Implement user code generation logic
        return "generated-user-code";
    }

    private String generateAccessToken() {
        // Implement access token generation logic
        return "generated-access-token";
    }

    private String generateRefreshToken() {
        // Implement refresh token generation logic
        return "generated-refresh-token";
    }
}

Step 6: Test the Flow

Use tools like Postman or curl to test the flow. Ensure that the device authorization and token exchange processes work correctly and handle various scenarios, such as valid and invalid device codes, expired codes, and successful token exchanges.

Conclusion

Implementing an OAuth2 Device Code Flow in Spring Boot with Spring Security enhances your application's flexibility by allowing devices with limited input capabilities to securely obtain access tokens. By following these steps, you can efficiently manage device authorization and ensure secure communication between devices and your server. Happy coding! 🚀

Hope this helps you in your Spring journey! Keep exploring and coding. 😊

OAuth2 Device Code Flow with Spring Boot