It can't be trivially unmasked. If approved researchers get controlled access to the data with oversight, but the data itself isn't shared with the companies.
There is no such thing. Information is not a physical good that you can store in a safe. Access to it implies sharing it. At best what you can do is an API limit so that the thing is not immediately copied in its entirety. But then again, what possible statistical insights could you gain with only a small fraction?
