You could always disconnect from the Win32 host, then reconnect with a test user that has no rights and see if the files are readable.

Solution1:
If the share point is C:\files and the encrypted directories are C:\files\encryp1 and so on...connect, write a file to encryp1, disconnect, reconnect with the test user and try to read the file.

This is a lot of overhead to do on each write, but cron a job for the evening to check if you can read some of the files shouldn't be so hard.

Solution2:
Write an admin accessable service on the Windows machine that you can query and will tell you if the file has been encrypted...this would be better than solution1

"Nothing is sure but death and taxes" I say combine the two and its death to all taxes!