Making a file readable only by JavaScript and/or Flash

I'm a bit new to web development so forgive the slightly beginner question. Can anyone give me some general pointers on how to prevent downloading of files while displaying content with JavaScript/Flash widgets?

The basic dilemma is making files playable by page widgets while preventing direct downloads of the source media. However, since JavaScript and Flash are browser-side instead of server-side, I'm not sure how I can do this.

Obfuscating the source file name is another option, but I'm not sure what a good way to do this would be. Maybe hiding with an algorithm in the .swf files? Not sure how immune to reverse compilation .swf is though.

Thanks a bunch.

In fact, you can't. There are two types of downloads; normal (direct) one and the one via streaming.

I would advise you to use the direct one but passing an authorization key with it.

An example of such a URL would look like:

/download?file=134&auth=A34C56E4FCD3908DA
    ^         ^          ^
    |         |          '- The predefined access token
    |         '- The requested file
    '- Gateway script

Don't forget that you must store the sensitive files somewhere outside of your document root.

The gateway script would look like (pseudo-code):

if( validate_token( get('auth') ){

    file_id = get('file');
    file_name = get_file_name( file_id );
    data = file_read_all( file_name );

}