SSL

SSL, the Secure Sockets Layer, is a cryptographic protocol designed to provide communications security over a computer network and on the Web. SSL is often related to HTTPS, for secured transmission with the HTTP protocol, although HTTPS has moved from SSL to TLS.

SSL is a PHP context for sockets, and share the configuration options with TLS.

<?php

$context = stream_context_create( array( 'ssl' => ['local_cert'=> $certificate_path], )));

if ($fp = stream_socket_client('ssl://'.$host.':'.$port, $errno, $errstr, 30, STREAM_CLIENT_CONNECT, $context)) {
    fwrite($fp, "\n");
} else {
   echo "Error: $errno - $errstr\n";
}

?>

Documentation

Related : ransport Layer Security (TLS), Universal Resource Locator (URL)