disdroc
Read this before you encrypt a chat.
End-to-end encryption keeps message content away from the server, and that same property means lost keys cannot be recovered by anyone. Here is what that means for you.
What encryption does not delete.
Turning on encryption for a chat does not delete anything. Messages sent before you enable it stay as they are and remain readable by the service. Only messages sent after that point are encrypted.
Encrypted messages can be lost for good.
The keys that unlock encrypted messages live on your devices, not on the server. If you log out everywhere, reset a device, clear browser data or lose your phone, and you have no other signed-in device and no recovery key, those messages can never be read again. Nobody, including the operator, can restore them.
Losing your account means losing access.
If you can no longer log in to your account, you cannot reach your encrypted history either. Even if you recover the account, a new device can read old encrypted messages only with your recovery key or by linking an existing signed-in device. Keep the recovery key somewhere safe and outside your devices.
Deleting your account deletes your messages.
If you delete your account, the messages you sent, including encrypted ones, are deleted with it, and so are your encryption keys and recovery backup. Other people in the chat lose those messages too. Deleted accounts cannot be restored.
It cannot be turned off.
Once a chat is encrypted it stays encrypted for everyone in it. In that chat, search, link previews, bots, server media filters and mention notifications stop working. The service can still see who talks to whom and when.
Full details: Privacy, security and trust