The US military agency DARPA is working on "unhackable" software for undisclosed security purposes, according to its director Arati Prabhakar.

The new tools are being created to run on embedded systems favoured by government and the armed forces, and is not intended to be used on mainstream servers and desktops.

Speaking to a cybersecurity summit, Prabhakar said: "Unfortunately there’s not going to be a silver bullet. There are pieces of this we think can become tractable.

"We’re working on a mathematical proof that the software can’t be hacked from the outside. It’s for embedded systems with a modest number of lines of code."

The agency is currently promoting a cybersecurity contest with a prize of $2m designed to attract the best talents from academia and computer industries, with the competition running from next year until 2016.

Since helping to fund the creation of the Internet the organisation has been working to secure computer technologies for the US government and military, as well as the country’s corporations.

"The moon shot for cyber, in my view, is to find techniques that scale faster than this explosion [of information]," Prabhakar added.

"This is incredibly technically challenging and challenging from a policy perspective."