You can always grab the request data and parse it any way you like. PHP provides a handy syntax to send arguments as arrays already, so why not use it?
If you need to pass any URI characters, a common example being passing a reference URL to an authentication scheme, be sure to run the string through urlencode(). You wouldn't need the quotes around your last example then...you'd essentially have this:
I couldn't get it to work. Thanks for your help though, I think i just did something wrong. I did something else and it works. Basically, I'm using NiftyPlayer (http://www.varal.org/media/niftyplayer/), an excellent little Flash mp3 player, to play music. The music is encrypted. To play the music, you embed nifty player like this:
I needed to decrypt the music before playing so I tried this:
This didn't work so I tried your suggestions but I don't think I did them right. What I ended up doing is to modify niftyplayer to append decrypt.php?file= to the file path it is given. This works perfectly. Thanks for your help though, I really do appreciate it!