Verifiable Secret Redistribution

We present a new protocol to perform non-interactive verifiable secret redistribution (VSR) for secrets distributed with Shamir’s secret sharing scheme. We base our VSR protocol on Desmedt and Jajodia’s redistribution protocol for linear secret sharing schemes, which we specialize for Shamir’s scheme. We extend their redistribution protocol with Feldman’s non-interactive verifiable secret sharing scheme to ensure that a SUBSHARES-VALID condition is true after redistribution. We show that the SUBSHARES-VALID condition is necessary but not sufficient to guarantee that the new shareholders have valid shares, and present an additional SHARES-VALID condition. This research is sponsored by the Defense Advanced Research Projects Agency (DARPA), Advanced Technology Office, under the title “Organically Assured and Survivable Information Systems (OASIS)” (Air Force Cooperative Agreement no. F30602-002-0523). The views and conclusions contained in this document are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of DARPA or the U.S. Government. Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE OCT 2001 2. REPORT TYPE 3. DATES COVERED 00-00-2001 to 00-00-2001 4. TITLE AND SUBTITLE Verifiable Secret Redistribution 5a. CONTRACT NUMBER