Protecting .swf Files?

I have a website that’s sort of like my personal portfolio where I can keep all my animations I make, photographs I take, etc. I would like to know how to protect my .swf files from being downloaded and edited. I know that there is a way.
You see, this person from my school downloaded one of my animations and put it on his site as his own. After realizing how vexing this can be, I’d like to learn how to protect my .swf files.
If you reply with an answer, I’ll be extremely grateful.
Thanks,
Eric Ko.