Changing Thresholds in the Absence of Secure Channels

The ways the threshold parameter can be modified after the setup of a secret sharing scheme is the main theme of this work. The considerations are limited to the case when there are no secure channels. First we motivate the problem and discuss methods of threshold change when the dealer is still active and can use broadcasting to implement This work was supported by the European Commission under ACTS project AC095 (ASPeCT) This work was partially supported by the Australian Research Council under grant number A49703076 Appeared in Proceedings of the 4th Australasian Conference on Information Security and Privacy (ACISP 1999), Lecture Notes in Computer Science 1587, J. Pieprzyk, R. Safavi-Naini, and J. Seberry (eds.), Springer-Verlag, pp. 177–191, 1999. c ©1999 Springer-Verlag