Verifiable Secret Redistribution for Threshold Sharing Schemes
Carnegie Mellon University Technical Report CMU-CS-02-114, February 2002 (revised).
Theodore M. Wong, Chenxi Wang*, Jeannette M. Wing
School of Computer Science
*Dept. of Electrical and Computer Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
We present a new protocol for verifiably redistributing secrets from an (m,n) threshold sharing scheme to an (m',n') scheme. Our protocol guards against dynamic adversaries. We observe that existing protocols either cannot be readily extended to allow redistribution between different threshold schemes, or have vulnerabilities that allow faulty old shareholders to distribute invalid shares to new shareholders. Our primary
contribution is that in our protocol, new shareholders can verify the validity of their shares after redistribution between different threshold schemes.