Untrustworthy participants in perfect secret sharing schemes. (English) Zbl 0814.94015

Ganley, M. J. (ed.), Cryptography and coding III. Based on the proceedings of the 3rd conference organized by the Institute of Mathematics and its Applications on cryptography and coding, held at Cirencester, GB, on Dec. 16-18, 1991. Oxford: Clarendon Press. Inst. Math. Appl. Conf. Ser., New Ser. 45, 255-264 (1993).
Summary: A secret sharing scheme protects a secret (key) by distributing related information among a group of participants. This is done in such a way that only certain pre-specified groups of these participants (the access structure) may reconstruct the secret. We discuss here a practical problem arising from the management of a secret sharing scheme – how to prepare for the possibility that some participant in the scheme at some stage becomes untrustworthy. We present a method for coping with this situation which involves giving several shares to participants in advance. The main advantage of this method is that in the event of some participant becoming untrustworthy, the new scheme to be used can be activated instantly by transmitting information on an insecure public channel.
For the entire collection see [Zbl 0790.00017].


94A60 Cryptography
68P25 Data encryption (aspects in computer science)