How to create a site with uploading a txt file with key generation?

Question

Online shopping

Essence in the following
I want to make a website for the sale of goods. It is necessary that the information is uploaded there in text form.
When selling, the buyer is given a pre-generated key, which he inserts on the site with a POST request and gets access to his product. The key must have an expiration date of 24 hours, a week, a month, etc. for example.
After choosing a product, the buyer receives this link with the unloading of the product in approximately this form.

Example:
site.ru/Home/GET/?key=Bm7e9Iz7URCr6lbASaz8&types=1

where key=Bm7e9Iz7URCr6lbASaz - this is where the problem

lies
. What do I need to learn and study?

Answer 1

php wordpress