Detecting SSL With PHP [duplicate]

Answer 1

WordPress's core is_ssl() function also adds a check for the server port:

function is_ssl() {
    if ( isset($_SERVER['HTTPS']) ) {
        if ( 'on' == strtolower($_SERVER['HTTPS']) )
            return true;
        if ( '1' == $_SERVER['HTTPS'] )
            return true;
    } elseif ( isset($_SERVER['SERVER_PORT']) && ( '443' == $_SERVER['SERVER_PORT'] ) ) {
        return true;
    }
    return false;
}

Answer 2

$_SERVER['HTTPS']

Set to a non-empty value if the script was queried through the HTTPS protocol.
Note: Note that when using ISAPI with IIS, the value will be off if the request was not made through the HTTPS protocol.

http://www.php.net/manual/en/reserved.variables.server.php

Ergo, this'll do:

if (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off') {
    // SSL connection
}