Remove allowed characters before name before alphanumeric test

application/config/aauth.php

@@ -43,6 +43,9 @@ $config['aauth'] = array(
     // pasword maximum char long (min is 4)
     'max' => 13,
 
+    // non alphanumeric characters that are allowed in a name
+    'valid_chars' => array(' ', '\''),
+
     // it limits login attempts
     'dos_protection' => true,
 

application/libraries/Aauth.php

@@ -297,7 +297,7 @@ class Aauth {
             $this->error($this->config_vars['pass_invalid']);
             $valid = false;
         }
-        if ($name !='' and !ctype_alnum($name)){
+        if ($name !='' and !ctype_alnum(str_replace($this->config_vars['valid_chars'], '', $name))){
             $this->error($this->config_vars['name_invalid']);
             $valid = false;
         }