/**
* Signs the API request.
*
* @param string $url
* @param string $verb
* @param string $content
* @return array
* @since 0.2.0
*/
private function sign($url, $verb, $content = null)
{
$current_date = date('c');
$request_info = $verb . $url . $current_date;
if ('POST' == $verb) {
$content_type = 'multipart/form-data; boundary=' . $this->mime_builder->boundary();
$request_info .= $content_type . $content;
}
$secret_key = base64_decode($this->credentials->secret());
$hash = hash_hmac('sha256', $request_info, $secret_key, true);
$signature = base64_encode($hash);
return 'HHMAC; key=' . $this->credentials->key() . '; signature=' . $signature . '; date=' . $current_date;
}