This Repository contains the backend of the Chat App.The backend is implemented using Express JS and Socket.io. Also For Database used in this project is mongoDB. Crypto-JS Library is Used For User Authentication And Also for the encryption and decryption of User Messages which are stored in Database. So This Chat App has got the feature of restoring the messages and it does not get deleted on Browser Referesh. Also This Chat App Has The Feature Of Chat Rooms.So a User Has To Join a room or create a room and invite others to start chatting. Each Room Has a admin and the admin has the special ability to remove a user from the room and also to delete a particular room. Users Can Also Leave a room if they want to..