These activities can be misconstrued, misinterpreted, and used to harm you as an individual even without the government having any intent to do you wrong.

I wasn't trying to change the laws or slow down the machine. Maybe I should have. My critics say that I was not revolutionary enough. But they forget that I am a product of the system. I worked those desks, I know those people and I still have some faith in them, that the services can be reformed.

You are also asked to take an oath, and that's the oath of service. The oath of service is not to secrecy, but to the Constitution - to protect it against all enemies, foreign and domestic. That's the oath that I kept, that James Clapper and former NSA director Keith Alexander did not. You raise your hand and you take the oath in your class when you are on board. All government officials are made to do it who work for the intelligence agencies - at least, that's where I took the oath.

The internet has to be protected from intrusive monitoring or else the medium upon which we all rely for the basis of our economy and our normal life, we'll lose that, and it's going to have broad effects as a consequence that we cannot predict.

How do we preserve our civil rights, our traditions as a liberal democracy, in a time when government power is expanding and is more and more difficult to check?

Anyway, it's not true that the authorities cannot access the content of the phone even if there is no back door. When I was at the NSA, we did this every single day, even on Sundays. I believe that encryption is a civic responsibility, a civic duty.

When it comes to cyber conflicts between, say, America and China or even a Middle Eastern nation, an African nation, a Latin American nation, a European nation, we have more to lose.