the data caging seems to be a feature of OS 9, which is not available yet. From NewLC:
"The second security feature is called data-caging. This prevents unauthorized access to date written on the file system and will be implemented at two different levels:
- system directories won’t be accessible anymore to applications (unless you have very high capabilities).
- each application can create a secure directory to store its sensitive information (registration information, credit card details,...) and other applications won’t be able to access it."
Which means that it is only a partial solutions, I'm sure there will be a hack that allows seeing & copying the content from these directories, since they are writettn somewhere in the file system anyway.
Currently you could try making your file read only & hidden, which doesn't really give you any protections. Basically only way to get some sort of protection, would be to use encryption for the files, then at least you would notice the modifications done, as well the content could not be read, unless ir can be hacket, which is propably very likely.
9.0 is an enabler release so you will actually have to get 9.1 to use data caging. I don't know what Nokia/UIQ's plans are for when an SDK based on 9.1 will be released but its going to be a while before any phones based on 9.1 appear I would guess.