Question about using a downloaded file as a coupon

So first let me say I am very new to any kind of web design, so sorry upfront.

I am setting up a store that will give a discount at checkout to Veterans, and to show proof I service I was going to make them provided a copy of a military ID.

I am not sure how the best way would be to accomplish this. At first I was going to have them email me the details of the order along with the ID copy and then manually fill the order, but I was just curious if there is some way to have a "coupon" feature at checkout where a image file can be attached. Is this possible, or are there any other options that I could use???

Thanks for any help.
Ben

Hi Ben,

I think that you can do it if you set a picture as a download file product and write the coupon's code on this picture.
Hope this will help you.

Thanks for the help,

I will look into both those options.

Just to clarify, with Hikaserial would that work for first time users? ie, someone visits the site and purchases an item and because they are a member of the armed forces would receive a discount, would there be an option to download some kind of picture file so I can verify they are really in the military at the time of checkout (in real time and not contacting me and then receiving some kind of ID code that can later be applied to the order)? Sorry for the confusion.

As to making a downloadable file with a coupon code as a purchased item, how would I get the file back with a picture of the ID?

Sorry for the noob questions....