ApaiIO\Configuration\ConfigurationInterface::getSecretKey PHP Method

    public function getSecretKey();

 /**
  * Calculates the signature for the request
  *
  * @param array $params
  *
  * @return string
  */
 protected function buildSignature(array $params)
 {
     $template = "GET\nwebservices.amazon.%s\n/onca/xml\n%s";
     return Util::buildSignature(sprintf($template, $this->configuration->getCountry(), implode('&', $params)), $this->configuration->getSecretKey());
 }