Modify PHP upload script to add encryption

I have a PHP file upload script that I use to allow users to upload multiple files from a web page to my server. While the files are being transferred they are protected by SSL, so that's not a problem. What I need is a subroutine (or two) that will require the user to enter a passphrase before the files are uploaded, which will encrypt the files once they reach the server, then when the files are downloaded by some other user, they can be decrypted using the same passphrase (symmetric encryption). I've been told that Crypt::Rijndael or something similar would work for this, and I've even been given some sample code, but I just don't have the time to learn PHP. I don't need an entire file upload script created, just the encryption subroutines added, and whatever needs to be installed on the server, if anything. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Installation package that will install the software (in ready-to-run condition) on the platform(s) specified in this bid request. 3) Complete ownership and distribution copyrights to all work purchased. ## Platform Web browser (IE, Netscape), installation on Windows 2000 server running Apache 2.0.44, PHP 4