If you want to lock your chat then follow the procedure
First, download WhatsApp Gb because normal WhatsApp does not support “Lock chat” Feature
- Install Downloaded GbWhatsApp apk.
- Set all things like a normal WhatsApp.
- Go on the chat screen of that specific person.
- Click on the 3-dot icon which is located on the upper-right.
- Now you will see the “Lock Conversation” option.
- Click on it, Choose a lock pattern or pin or fingerprint.
- Set your password and you are done.
Now whenever you want to chat with that person, First you have to unlock chat.