This is a scripting tutorial directed toward beginngers in security hashing, it is mainly to compare passwords for accepting commands via llLinkMessage();
Note: This is NOT secure for transfering data, it IS secure on accepting / declining commands that are sent by an unknown script.
If you can't read the tutorial, the link to this is at my wiki:
http://www.punkydesigns.com/PunkysWiki.php
Click on 'snippets' and it's at the bottom