Simple php / MySQL application to share secret info

Developer must have own environment (MySQL & PHP) to create a working project for testing. Once tested, we will release payment and the full set of project files must be supplied. This must work on php7.4 with Mariadb 5.6 (or equivalent Mysql). We would prefer this in Pure PHP and not in a framework. Background: We want to create a secure secret info sharing platform that will not store any raw data and will automatically expire access to data. $SecretKey=ABC12345 $IV=XYZ99999 1. Page will be on a subdomain [login to view URL] The page has a box to add text (up to 3000 characters) 2. Page has a 'Passphrase' box to enter a passphrase up to 100 characters 3. Selection dropdown of expiry (5 min, 30 min, 1 hour, 4 hour, 12 hour, 24 hour, 3 day, 5 day, 7 day) 4. Submit button When user submits, it will encrypt the data ideally using php and using AES 256 method using CONCAT($SecretKey,'$',$Passphrase) along with the IV. 4. The encrypted data is stored onto DB table along with the expiry date in unix format and a hash of the passphrase and a random retrieval link address /sharepass/dfiaswewunx323oijd, and a viewed_date in date&time format. 5. Display on the page: Retrieval link Expiry (in date & time format) To decrypt the secret info: 1. go to URL 2. Enter Passphrase 3. Submit The page must: a) check the link is valid. If it is not then show message "Sorry this link is not valid" b) if the link is valid, but the viewed_date >0000-00-00 show message "Sorry this message has already been viewed and deleted" a) check the expiry date of the data - if it is after the expiry, then delete the row and show message "Sorry this message has expired" b) if not expired then check the hash of the passphrase matches the stored hash in the db. If it is wrong then show message: "Sorry this passphrase is incorrect" c) If not expired and passphrase hash matches. Then decrypt data and display on the page. AND immediately UPDATE the message ='', viewed_date=now()