It's much more important for U.S. to be able to defend against foreign attacks than it is to be able to launch successful attacks against foreign adversaries.

I must say I'm surprised by how skeptical of the [Barack] Obama administration The Nation has been.

Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on. Unfortunately, endpoint security is so terrifically weak that NSA can frequently find ways around it.

In the United States, there hasn't been much legislative change on the surveillance issue, although there are some tepid proposals.

I talk to cryptographers, some of the leading technologists in the world, all the time about how we can deal with these issues. It is not possible to create a back door that is only accessible, for example, to the FBI.

The new iPhone encryption does not stop them from accessing copies of your pictures or whatever that are uploaded to, for example, Apple's cloud service, which are still legally accessible because those are not encrypted. It only protects what's physically on the phone.

Custom developed digital weapons, cyber weapons nowadays typically chain together a number of zero-day exploits that are targeted against the specific site, the specific target that they want to hit. But it depends, this level of sophistication, on the budget and the quality of the actor who's instigating the attack. If it's a country that's less poor or less sophisticated, it'll be a less sophisticated attack.