Further, the next generation of terrorists will grow up in a digital world, with ever more powerful and easy-to-use hacking tools at their disposal.

The concern is over what will happen as strong encryption becomes commonplace with all digital communications and stored data. Right now the use of encryption isn't all that widespread, but that state of affairs is expected to change rapidly.

However, leaving everything to the market is not necessarily good for society.

I don't have a particular recommendation other than that we base decisions on as much hard data as possible. We need to carefully look at all the options and all their ramifications in making our decisions.

I favor strategies that encourage industry to include some sort of key recovery capability in their systems which would also address user requirements for access.

If we take as given that critical infrastructures are vulnerable to a cyber terrorist attack, then the question becomes whether there are actors with the capability and motivation to carry out such an operation.

Although cyber attacks have caused billions of dollars in damage and affected the lives of millions, few if any can be characterised as acts of terrorism.