Rational Secret Sharing Research Based On Repeated Games

Secret sharing is an important part of cryptography, which provides a totally new idea of key management, and plays an important role in keeping, delivering and using the secret key. Secret sharing can share risks and prevent the excessive concentration of manage power of secret key, which is of great importance to improve the security and robustness of the system.This dissertion introduces the fundamentals of sharing threshold secret, analyzes the classical verifiable secret sharing schemes and multi secret sharing schemes, and discusses the problems existing in these schemes. It introduces knowledge related to game theory, states the concept of Nash Equilibrium and mechanism of repeated game and analyzes typical rational secret sharing schemes. Based on repeated game mechanism, a peaceful rational secret sharing schemes is proposed. The program has the following features:(1) Based on repeated game mechanism, through several rounds of interact secret share and punishment mechanism, make the participants rationally submit the true sub-secrets in interactions. Set random game rounds and every participant’s secret number should be different. When the participant submits the last secret, it cannot be told if the current interaction is the last round. Thus the issue of the last round cheating is solved.(2) Give an improved punishment mechanism, once the participants cheat in current interaction, will be punished in next interaction. The improved punishment mechanism can not only guarantee the benefits of honest participants, but also can give a chance for the deceivers to mend their ways, which has better robustness and fairness(3) The secret dealer sign the sub-secrets, and then distributed to the participants. The participants test whether the sub-secrets are true or not in interactions, once it detects that there are participants cheating, the beguilers shall be punished. To participants, the earnings after their cheating is found to be far less than submitting the secrets truthfully. Therefore, rational participants will submit sub-secrets truthfully.At last, under the environment of Win7, we realize the prototype system of this scheme by using Visual Studio 2010, and the experiment results show that the scheme is correctness and feasibility.