Steganography algorithms enable ‘perfectly secure’ information

This is the claim of a team led by Oxford University in collaboration with Carnegie Mellon University. They believe their method could soon be used in digital human communications, including social media and private messaging. The ability to send ‘perfectly secure’ information could be advantageous to vulnerable groups, including dissidents, investigative journalists, and humanitarian aid workers.

According to Oxford University, the algorithm applies to steganography, which is the practice of hiding sensitive information inside of innocuous content. Steganography differs from cryptography because the sensitive information is concealed in such a way that this obscures the fact that something has been hidden.

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Despite having been studied for over 25 years, existing steganography approaches generally have imperfect security, so individuals using these methods risk being detected because previous steganography algorithms would subtly change the distribution of the innocuous content.

To overcome this, the research team used recent breakthroughs in so-called minimum entropy coupling, which allows someone to join two distributions of data together such that their mutual information is maximised, but the individual distributions are preserved.