There is no inbuilt way of locking QVD files. The only security for QVD files is the security of the folder or location where they are stored. If access to this store location is not restricted, then the information in the QVD is available to anyone.
HTH
Jonathan
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein
to secure the data model write you entire script in the hidden script, so that it will be password protected and no one can see you script but table viewer cannot be hidden.
For the qvd lock go with the folder security option, as per my knowledge nothing else can be done with this.
