slickorange

This simple plugin enables you to set up different access codes or passwords that enable users to be added to specific WordPress Roles or Press Permit (http://presspermit.com/) permission groups.
Simply go to Settings -> WP Access Codes to create and manage your codes.
Use the [wp-access-codes] shortcode to display the input field in the frontend.
More features planned! Please make your feature requests in the support area or send a mail to info@slickorange.co.za

WP Access Codes

Assigns a WordPress Role or/and a Press Permit Group to a user based on a predefined access code they enter.

Kevin Pirnie

This plugin generates the proper security HTTP response headers, attempts to generate a valid Content Security Policy, and sets browser permissions if configured.

Security Header Generator

Excellent

This plugin generates the proper security HTTP response headers to keep your site secured.

WP Access Codes vs Security Header Generator