2023-05-17 09:31:53
Steganography makes it possible to hide sensitive information in innocuous content such as a photo. But until now, the algorithms somewhat modified the innocuous content used. Even if it is minimal, this alteration can arouse the suspicion of cyberattackers. British researchers claim to have developed an algorithm that no longer alters the medium at all, which reinforces the confidentiality of exchanges.
Sensitive information must be kept confidential to preserve its value. To ensure the confidentiality of this type of data, companies use solutions that “encrypt” (the general public rather knows the – inappropriate – term of “encrypt”) the content transmitted by email or stored in the cloud.
But the encrypted information is identifiable, its passage is visible on the network. However, a key is required to decrypt it. Depending on the algorithms used, some time and some computational resources are required to find the key.
The ideal is therefore to be sufficiently discreet so that we do not guess the presence of the information that we want to protect. This is what “steganography” offers, a technique that already existed in the Middle Ages.
More hidden information
Very little used by companies, it is still confined to research. And in this area, researchers from the University of Oxford and Carnegie Mellon University claim to have developed an algorithm very effective.
Although they have been studied for more than 25 years, existing steganography methods generally have imperfect security, which means that people who use them are at risk of detection. Indeed, the previous steganography algorithms somewhat modify the harmless content used (a sound, images or videos).
To remedy this, the research team used recent advances in information theory, in particular minimum entropy coupling, which allows two data distributions to be associated in such a way as to maximize their mutual information, while preserving the individual distributions.
Therefore, with the new algorithm, there is no difference between distributing innocuous content and distributing content that encodes sensitive information.
In addition to being perfectly safe, the new algorithm has shown up to 40% better encoding efficiency than previous steganography methods in a variety of applications, allowing more information to be hidden in a single harmless file.
The research team has filed a patent application for the algorithm. But it will be under a free license for responsible non-commercial use, for example for academic and humanitarian research.
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