Are all my private data now public information?
What about Data Privacy in Blockchain?
Everybody gets a copy of my data so does it mean that my private data is now publicly available?
Well, yes and no. Remember that I mentioned about it being globally verifiable? The good thing is that it need not be stored in whole and in clear on the blockchain.
The blockchain network could just store the hash of your data and it would prove the integrity and existence of the original piece of information stored in your own private system. In this setup, the hash is public while your data are still private.
Of course, there are other techniques like data encryption if you choose to keep the data on the blockchain network.