插入唯一代码下载文件[关闭]

I would like to make a page where you insert a unique code it links you to a specific file for that code. Something like this website. http://animalstylerecords.com/downloads/

A few pointers:

• store the files somewhere outside the web root, where people can't simple download them by guessing the URL; see How do I prevent public downloads of files using php?
• somehow map codes to file names; this could be a simple array or a whole database, depending on your needs
• confirm that a code is valid and output the requested file using readfile, look at the example on the manual page