C / C++ / MFC

/** Create a device that is authenticated using ES256. */
public static void createDeviceWithEs256(String deviceId, String publicKeyFilePath,
    String projectId, String cloudRegion, String registryName)
    throws GeneralSecurityException, IOException {
  GoogleCredential credential =
      GoogleCredential.getApplicationDefault().createScoped(CloudIotScopes.all());
  JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
  HttpRequestInitializer init = new RetryHttpInitializerWrapper(credential);
  final CloudIot service = new CloudIot.Builder(
      GoogleNetHttpTransport.newTrustedTransport(),jsonFactory, init)
      .setApplicationName(APP_NAME).build();

  final String registryPath = String.format("projects/%s/locations/%s/registries/%s",
      projectId, cloudRegion, registryName);

  PublicKeyCredential publicKeyCredential = new PublicKeyCredential();
  final String key = Files.toString(new File(publicKeyFilePath), Charsets.UTF_8);
  publicKeyCredential.setKey(key);
  publicKeyCredential.setFormat("ES256_PEM");

  DeviceCredential devCredential  = new DeviceCredential();
  devCredential.setPublicKey(publicKeyCredential);

  System.out.println("Creating device with id: " + deviceId);
  Device device = new Device();
  device.setId(deviceId);
  device.setCredentials(Arrays.asList(devCredential));

  Device createdDevice =
      service
          .projects()
          .locations()
          .registries()
          .devices()
          .create(registryPath, device)
          .execute();

  System.out.println("Created device: " + createdDevice.toPrettyString());
}