How to keep an eye on our data as it moves from one owner to another is a tricky problem that Ryan Shea and Muneeb Ali have been working on since 2013. When the pair founded Blockstack, a new kind of app marketplace, they flipped the model on its head. What if, instead of trusting companies to hold all your data, the information always stayed with you, on your computer or a cloud storage provider of your choice? And what if, every time a new app wanted to access your data, you simply gave it a key that could decrypt all that personal information that you controlled? If you later decided the app was no good, you could just take back the key.