Sharing content through network (E-Learning software)

Hi!..

I´m trying to program an e-learning software where user connects to a remote server, this program is a downloadable client "Student".
There will be another application called "Instructor", the instructor can create contents so this will be rendered into the "Students" program.

For example:

Instructor creates a new module where attach an image, audio and some text, clicks on save button, this content will upload into a server.
Student next time logging in will see this new content in his application.

I know an easy way to port the content, is just using PDF documents, so instructor generates it and upload, then student in background download it and renders
But I´m wondering if there is another way to share it, I mean something more private..

Is there any alternative to pdfs?
Thanks

Quote:

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Is there any alternative to pdfs?

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You can always password-protect PDF files or create a passworded ZIP file that you automatically create when a student requests and downloads an instructor's content. You can use the student's login name and password as the password for the ZIP file when you create it. On the student side, after the file is received, you can automatically decrypt it into a temporary file. That temporary file can be deleted when the user closes it.

placing password to pdfs is a good option...
Thanks