code: protected function getEntityId($blockType, $config, $params = array())
      {
          $entityId = null;
          if ($blockType === "account" && isset($params["name"])) {
              $entityId = md5($params["name"]);
          } elseif ($blockType === "email" && isset($params["email"])) {
              $entityId = md5($params["email"]);
          } elseif ($blockType === "ip") {
              $entityId = $this->getIp($config);
          }
          return $entityId;
      }
docs: Gets an entity identifier
  
  Returns a string that will identify the entity
  in the rate limiting process. It can be a hash of a username/email,
  or IP subnet of a size defined by the configuration.
  
  md5 is applied on a user-supplied input (email, username),
  collisions or reversibility do not present security concerns.
  
  @param string $blockType Blocking type (account,email,ip)
  @param array $config Configuration array for the specific rate limit
  @param array $params Additional parameters from the action() call
  @return string Entity id