Search & Download from Dropbox Folder by filename

Hello,

I want to create a file retriever on my website that is a simple input text box. My clients can enter a particular code I provide them with and if their code matches the filename of one of the files in that folder, the file will download to their computer.

I am a photographer and am trying to automate the way that clients get their digital files from me. Each client is already assigned a unique identifier and my software is capable of outputting their photo as their-code.jpg. So, if I could write a web app of some sort that takes their-code and searches my dropbox folder for any files with that filename and if found, starts a download. It would be a lifesaver.

Anybody ever heard of anything like this? Any ideas on how to accomplish it?

Thanks!