Customer access to file by password

I do not know what this functionality is called, or even if there is such functionality available, but I was hoping that this great community can help me:

I need to have a static, visible page on my website where customers can enter passcodes, with each customer having a unique passcode, and depending on which passcode is entered, a customer-specific file will be downloaded or displayed.

Is this even possible, and if so, how?

Thank you in advance!