Login with Username (or Code) only

Question

We are building a landing page site (only 2 pages total) for a client where they are physically mailing out access codes to specific customers. Therefore, I am trying to create a login system where ideally, a user logs in with a pre-determined access code. I have been trying different hacks of a login type of but nothing is working to create a single-step, simple process.

The "verification" system that this site uses is close to what I'm looking for, but this system first verifies a purchase, then invites you to Register for a WP account. http://support.hogash.com/wp-login.php?action=register

I don't want users to have to register anything - I just want have a single entry field with pre-determined access-codes that then allows access to a secondary page.

This solution of pre-filling a password may have worked but the lack of pre-filling passwords won't work. We could have had the password field pre-determined and pre-filled (and possibly hidden) then the user enters his/her access code (i.e. username) How to prefill the username/password fields on the login page

I have searched hours over a few days for different solutions but nothing. Any ideas on how to solve this?

UPDATE 12/26/13: One of the most promising plugins that I've tried, at least on paper, is "Password Only Login" http://wordpress.org/plugins/password-only-login/

Via settings, you select what users you want to be able to login via special form w/ password only. But the shortcode to get the login form to show up on a page doesn't work. I've already reached out to the author, but ain't holding my breath.

Answer 1

Would this free plugin help? http://wordpress.org/plugins/password-protected/

Perhaps you can use turn on the simple login for admins (requires password), then write a custom redirection script by modifying the plugin or add to functions.php so that if the password is correct, they are logged into a specific URL instead of the dashboard.

Answer 2

Here is an suggestion, create a plugin on your own. The plugin should contains the access code generated manually by your client. It should have add/remove access codes options.

By having the access code you can do two type of access.

One is directing the end user to the destination page with the access code as query parameter. This url can be sent to the end user.

You need to grab the access code using get variable $_GET[''] and then check in your plugin db. If the access code is present then allow them to view the page or redirect them to 404(some error message).

Second method is to create a user programmatically with the mail ID your client mailed the end user, username as access code and set the password randomly. In the custom login page just allow the end user to enter the access code. Upon successful access code enter auto authenticate the user.

Let me know if you have any doubts.