Yes! has invested a lot of time and resources to build PS in the most secure way possible. If you are unsure about how to secure your app, or are worried about storing data (which is a real concern), there is a solution. You can request data  via PS, process it to provide your functionality, and then throw it away (discard it from memory).

For example, if you are providing a credit rating service, you might ask to see an individual's financial transaction history to create a credit score. Once that score has been calculated, you no longer need the detailed financial data and would do well to discard it immediately.