Teach me how to generate PCODE in PHP.

PCODE stands for "Proof Code" It is a useful feature to automatically verify and/or auto-rate tasks in Small Jobs. By implementing PCODE on a website: The system can Verify (V) tasks automatically, then wait for Employer to review and rate tasks manually The system can Verify+Rate (V+R) tasks automatically as Satisfied In order to perform verification or auto-rating of tasks, you must display a task verification code (PCODE) to each Worker who has successfully finished a task on your website. Example: You ask a Worker to perform a sign up to your website. Once he/she finishes a signup process, your website will calculate PCODE for that Worker and display it on screen. Each Worker will receive a unique PCODE to submit to a workers proof box. I want you to teach me the steps of how I will do that and what are the tools I will need. Thank you