I'm about to work on my first ethereum project.
When a user opens the MySecretApp, they will create a transaction on the ethereum blockchain.
My questions are:
1) Am I sharing the ethereum blockchain (and the billion existing transactions) with other companies? Or can I create a new chain that only contains transactions coming from MySecretApp?
1) How do I verify that a hacker with an app called HackersFakeApp doesn't publish a transaction to my chain? I only want to store transactions that come from my app.