Perfectly secure steganography: Hiding information in the quantum noise of a photograph
Bruno Sanguinetti, Giulia Traverso, Jonathan Lavoie, Anthony Martin, Hugo Zbinden · Physical Review A · 2016
We show that it is possible to hide information perfectly within a photograph. The proposed protocol works by selecting each pixel value from two images that differ only by shot noise. Pixel values are never modified, but only selected, making the resulting stego image provably indistinguishable from an untampered image, and the protocol provably secure. We demonstrate that a perfect steganographic protocol is also a perfectly secure cryptographic protocol, and therefore has at least the same requirements: a truly random key as long as the message. In our system, we use a second image as the key, satisfying length requirements, and the randomness is provided by the naturally occurring quantum noise which is dominant in images taken with modern sensors. We conclude that, given a photograph, it is impossible to tell whether it contains any hidden information.