Add Feature to Custom PHP API

I have a custom built php API that allows developers to post content to my popular web app. Its a standard RESTFUL API coded using php. I need a feature added to the API: * API Key. Currently, anyone can post to the site using the API without any type of key. I would like to add an extra parameter - the API key, which developers would need to include when interfacing with the API. You will also need to code a small script that generates a key, and stores it in the database. (this would simply be a button that once clicked generates a unique key - no authentication is required). PLEASE pm me to get details of the API and the name of the application you'll be working with. If work is done to a high standard and at a good price, ongoing work will be offered to you.