class PrivateKey

class PrivateKey {
  
  /**
   * The state service.
   *
   * @var \Drupal\Core\State\StateInterface
   */
  protected $state;
  
  /**
   * Constructs the private key object.
   *
   * @param \Drupal\Core\State\StateInterface $state
   *   The state service.
   */
  public function __construct(StateInterface $state) {
    $this->state = $state;
  }
  
  /**
   * Gets the private key.
   *
   * @return string
   *   The private key.
   */
  public function get() {
    if (!($key = $this->state
      ->get('system.private_key'))) {
      $key = $this->create();
      $this->set($key);
    }
    return $key;
  }
  
  /**
   * Sets the private key.
   *
   * @param string $key
   *   The private key to set.
   */
  public function set(#[\SensitiveParameter] $key) {
    return $this->state
      ->set('system.private_key', $key);
  }
  
  /**
   * Creates a new private key.
   *
   * @return string
   *   The private key.
   */
  protected function create() {
    return Crypt::randomBytesBase64(55);
  }

}