PHP Script Change

I have a php scripts (wordpress plugin). I require a very simple registration system. By default the script should ask for a code to enable registration. Until a code is entered by the user the script does not work. The user can obtain the code by emailing a particular email address, but you do not have to worry about that. We will tell you a screen to change telling the user the instructions to register. The code will be returned to the user in an email and they will paste in the code. To verify if the code is valid, your change will post to another script (which you develop) the code entered by the user, and the script name (so that it handles all 4 scripts). That script will have a very simple set of if/then conditions set. if code = "code" then return true . . . return false If false is returned from the function an invalid code is supplied. As the script is distributed unprotected there is a need to make sure it's not a simple change for someone to remove the registration process. So you need to make it hard for the casual person to know what to change to avoid registration. It is ok if experienced coders can figure it out. Once registered the script should be permanently activated. If you have a better registration idea that does not involve encoding/encrypting the source code please let us know. All 4 scripts essentially do that same thing, they post some content from a website to a number of other websites. They "login" to these websites with stored usernames and passwords. You will also add functionality to post the same content to two more websites. You should easily be able to add this functionality by looking at the existing code and adapting it. It already posts to 20 websites.