Try these:
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($ch, CURLOPT_CAINFO, '/etc/pki/tls/cert.pem'); // path is valid for RHEL/CentOS
This makes sure the resource you're "curling" has a valid SSL certificate. It is not recommended to set "CURLOPT_SSL_VERIFYPEER" to false (0).