I need a one group simple chat app works with Firebase that auto deletes messages when they reach 40. -- 2

Job ID: 32284285

Budget: $30 – $250 USD

Main idea: very simple group chat app (one group).

You have to make a group chat app that anyone can join by creating an anonymous account. The group must automatically delete messages when they reach 40, but there's a catch; messages must be secure and can't be deleted/edited by anyone who gets the Firebase credentials.

You can use Firebase for the database and Java for the project.
Note: create a private GitHub repository and share it with me so I can stay updated with your work.

Additional feature: the ability for the user to delete his own messages.