Add is_https() as a common function
diff --git a/system/core/Security.php b/system/core/Security.php
index b22d2cf..2fbc5b3 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -198,7 +198,7 @@
 		$expire = time() + $this->_csrf_expire;
 		$secure_cookie = (bool) config_item('cookie_secure');
 
-		if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off'))
+		if ($secure_cookie && ! is_https())
 		{
 			return FALSE;
 		}