First of all, we remind you that you should ALWAYS keep a backup copy of the Encryption Key in a safe place, as instructed during the setup of our application on the Primary Device.
Still, if you haven't kept this backup copy in a safe place and a hacker is able to get it, it will still be very difficult to access the messages. For that the hacker would have to:
1 - Know the password you used when you created the backup copy of your encryption key, because your key is stored encrypted by this password;
2 - Have physical access to your authorized devices. Only with an authorized device is it possible to login to your account;
3 - Know Your Username;
4 - Know your Password.
The other encryption keys, used individually for each message, are volatile. This means they're not kept anywhere. Instead, they are created and discarded immediately after being used to encrypt a message. Similarly, if your messages are sent, when your recipients receive them and answer the encryption questions correctly, these keys are recreated, used to decrypt the messages and discarded, also immediately.