I am building an exchange for crypto currency. I need to be able to transfer tx from cold storage(offline) to hot wallet(online system) for submission. Usb stick is suitable for an individual user mining but is not suitable in an exchange environment.
One option I am proposed is to build an api that sends tx over ethernet cable to and from cold/hot storage. But in this case the cold storage wont really be offline, it would still be connected. So what other options do I have that could work well for an exchange?