Our smartphones are quickly becoming on-the-go computers, so it only makes sense that the amount of data that we access on them is becoming greater, too. When we want to share files between computers and our Android phones, there are quite a few services available - like Dropbox, for example. But there is one problem with services like Dropbox: security. Sure, they may be fine for uploading pictures of the family dog or easily transferring MP3s to your Android device, but what about sensitive data?