This is the shared secret that will be used to encrypt passwords sent
by the NAS. The shared secret is a secret word or sentence that is used to
protect all information passed between the NAS and Radiator. It must be
configured here and also configured into the NAS. It must be configured
exactly the same the NAS. It is case-sensitive. We recommend that you use
a shared secret containing mixed case letters and number of about 16
characters.