[toinejuan]

In the settings tab there is an encryption button, you can use this to make your SD unreadable by anything other than your device. I am sure it's a double edged sword because if you happen to lose you TP you may have some trouble retrieving the data you want back.
I personally, don't use it but, there's probably a way to unlock the encryption since it's inside your TP. Also since you can plug it in and use it as a flash drive your in luck. You should probably give that a go.