Если у вас есть расширение curl, его можно настроить для проверки сертификата при подключении.
http://php.net/manual/en/function.curl-setopt.php
// As of writing this, Twitter uses Verisign, Google uses Eqifax
$exampleUrl = 'https://twitter.com/'; // Success
$exampleUrl = 'https://google.com/'; // Fails
// create a new CURL resource
$ch = curl_init($exampleUrl);
// enable verification
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
// list of CAs to trust
// If the remote site has a specific CA, they usually have a .crt
// file on their site you can download. Or you can export key items from
// some browsers.
// In this example, using: Verisign [1]
curl_setopt($ch, CURLOPT_CAINFO, __DIR__ . '/ca_bundle.crt');
// - or -
curl_setopt($ch, CURLOPT_CAPATH, __DIR__ . '/ca_certs/');
// If the remote site uses basic auth:
curl_setopt($ch, CURLOPT_USERPWD, $username . ':' . $password);
// And a helpful option to enable while debugging
//curl_setopt($ch, CURLOPT_VERBOSE, true);
// defaults to stdout, don't want that for this case.
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$page = curl_exec($ch);
[1] http://www.verisign.com/support/verisign-intermediate-ca/extended-validation/apache/