This is a private key generator. Normally, you will use this function only once during the setup (or you will not use it at all if you have restored your private key from the backup document or generated it using omsCompanion).
Fill in the key alias and the transport password, click CREATE. OneMoreSecret will generate a backup document for you. Please make sure you have saved it before checking the box and activating the key. It will not be stored on the phone until you click ACTIVATE.