What ive done is encrypt usbs which i continually update. Its a little bit time counsming but worth it. Also..make sure one person beside you and your spouse know the usb key. If you both die in a car crash that person (your brother sister dad uncle) can unlock the usbs. Also keep one copy in their house. But with a password they DONT know. Thats in case your house burns down(without you in it) or the location where your usb is compromised.