Characterization of optimal key set protocols Original Research Article

Using a random deal of cards to players and a computationally unlimited eavesdropper, all players wish to share a common one-bit secret key which is information-theoretically secure from the eavesdropper. This can be done by the so-called key set protocols. In this paper, we give a necessary and sufficient condition for a key set protocol to be “optimal”, that is, to succeed always in sharing a one-bit secret key.