Prevent running arbitrary code. Possible Security Policies on Network Connections No network connectivity. Limited network connectivity. Limited network connectivity. Limited network connectivity.
Applets signed by approved secret key have full access to the computer's resources.
Unsigned applets are restricted. E.g., applet from specific vendor are allowed. Navigator 4.0 Java Policy open Java sandbox, allowing applets more functionality and flexibility. It uses digital signatures and digitally signed capabilities. You can edit privileges of certificates.