Pairs of photons generate a completely random string of digits that are received by both a sender (Alice) and a receiver (Bob). They both convert the string of digits into a "snow" pattern just like those on TV sets. Then, Alice takes an image of the Venus von Willendorf (a), and adds the snow pattern to the image, completely garbling it (b). Bob then receives the garbled image, and subtracts the snow pattern to get the intended image (c).
Reported by: Jennewein et al. in an upcoming issue of Physical Review Letters