Cheating The (2,N) Visual Secret Sharing Scheme
Horng et al. proposed a method that allows colluding parties to cheat an honest party in visual cryptography. They take advantage of knowing the underlying distribution of the pixels in the shares to create new shares that combine with existing shares to form a new secret message of the cheaters choosing.
We know that 2 shares are enough to decode the secret image using the human visual system. But examining two shares also gives some information about the 3rd share. For instance colluding participants may examine their shares to determine when they both have black pixels and use that information to determine that another participant will also have a black pixel in that location. Knowing where black pixels exist in another party's share allows them to create a new share that will combine with the predicted share to form a new secret message.
In this way a set of colluding parties that have enough shares to access the secret code can cheat other honest parties.
Read more about this topic: Visual Cryptography
Famous quotes containing the words cheating, visual, secret, sharing and/or scheme:
“It’s perversion. Don’t you see what it is? It’s not natural. To go to great expense for something you want, that’s natural. To reach out to take it, that’s human, that’s natural. But to get your pleasure from not taking, from cheating yourself deliberately like my brother did today, from not getting, from not taking. Don’t you see what a black thing that is for a man to do? How it is to hate yourself?”
—Abraham Polonsky (b. 1910)
“I may be able to spot arrowheads on the desert but a refrigerator is a jungle in which I am easily lost. My wife, however, will unerringly point out that the cheese or the leftover roast is hiding right in front of my eyes. Hundreds of such experiences convince me that men and women often inhabit quite different visual worlds. These are differences which cannot be attributed to variations in visual acuity. Man and women simply have learned to use their eyes in very different ways.”
—Edward T. Hall (b. 1914)
“The vanity of being known to be trusted with a secret is generally one of the chief motives to disclose it.”
—Samuel Johnson (1709–1784)
“So close is the bond between man and woman that you can not raise one without lifting the other. The world can not move ahead without woman’s sharing in the movement, and to help give a right impetus to that movement is woman’s highest privilege.”
—Frances Ellen Watkins Harper (1825–1911)
“I have no scheme about it,—no designs on men at all; and, if I had, my mode would be to tempt them with the fruit, and not with the manure. To what end do I lead a simple life at all, pray? That I may teach others to simplify their lives?—and so all our lives be simplified merely, like an algebraic formula? Or not, rather, that I may make use of the ground I have cleared, to live more worthily and profitably?”
—Henry David Thoreau (1817–1862)