The caller wants to know if backing up data to DropBox is secure? He's worried that backup companies have access to his sensitive data. Leo says he can encrypt the data, and he alone has the keys to that. So if he loses it, he's out of luck. DropBox will accept secure encrypted data. If he's looking for a cloud-based encryption backup option, SpiderOak is an option, though it's a bit clunky. VeraCrypt is another.