Note on Threshold Schemes with Disenrollment

摘要

Blakley, Blakley, Chan and Massey conjectured a lower bound on the entropy of public broadcast in a threshold scheme with disenrollment capability. In this paper, we first show that the conjecture need not be true in general. Then we establish a tight lower bound on the entropy of public information by introducing one property to the definition of threshold schemes with disenrollment. We also present a scheme that achieves the lower bound.