How to Implement URL Signing for HighWinds CDN in PHP:
//the input URL example taken from https://support.highwinds.com/display/DOCS/Content+Protection
$URL = parse_url("http://aaa.wdd3.cdn.net/secure123/content.mp4");
// parse URL to separate the host and the rest of the url string
$uri= $URL['path'];
// set a secret pass
$secret = 'abcdef123';
// set a delay for expiration date of token
$delay = '60';
// generate epoch for expiration date
$ttl = time() + (1 * 1 * 1 * $delay);
// create url for md5 hashing
$message = $uri . "?ttl=" . $ttl . "&pass=" . $secret;
// create md5 hash of the prepared url
$digest = md5($message);
// return finalized url as per the documentation
$token_value = "?ttl=" . $ttl . '&token=' . $digest;
//return or echo the value
echo $token_value;