'Breakthrough’ in quest for perfectly secure digital communications

A breakthrough algorithm conceals sensitive information so effectively that it is impossible to detect that anything has been hidden, researchers said on Tuesday.

The system — which uses steganography instead of cryptology — is so secure it could allow vulnerable groups such as dissidents to communicate more safely with the outside world, they said.

It could also allow investigative journalists and humanitarian aid workers to communicate easier in some countries.

The algorithm may soon be used widely for digital communications, including social media and private messaging, the team led by the University of Oxford said.

“Our method can be applied to any software that automatically generates content, for instance, probabilistic video filters or meme generators,” said the study's co-lead author Dr Christian Schroeder de Witt.

“This could be very valuable, for instance, for journalists and aid workers in countries where the act of encryption is illegal.

“However, users still need to exercise precaution as any encryption technique may be vulnerable to side-channel attacks such as detecting a steganography app on the user’s phone.”

The algorithm works in steganography, where sensitive information is hidden inside innocuous content, for example hiding a word message inside a digital painting.

Recent advances have helped develop steganography techniques that are perfectly secure, the researchers said.

Previous steganography algorithms would subtly change the distribution of the innocuous content, meaning the changes could also be detected.

To overcome this, the research team used recent advances that allow different sets of data to be sent without the corruption.

Besides being perfectly secure, the new algorithm showed up to 40 per cent higher encoding efficiency than previous steganography methods, they said.

That would allow more information to be concealed within a given amount of data.

The research team has filed a patent for the algorithm, but intend to issue it under a free licence to third parties for non-commercial responsible use, including in the academic and humanitarian fields.