Affiliation: Bilkent University
Secret Sharing Extensions based on the Chinese Remainder Theorem
In this paper, we investigate how to achieve verifiable secret sharing (VSS) schemes by using the Chinese Remainder Theorem (CRT). We first show that two schemes proposed earlier are not secure from an attack where the dealer is able to distribute inconsistent shares to the users. Then we propose a new VSS scheme based on the CRT and prove its security. Using the proposed VSS scheme, we develop joint random secret sharing~(JRSS) and proactive SSS protocols, which, to the best of our knowledge, are the first secure protocols of their kind based on the CRT.
Optimal Subset-Difference Broadcast Encryption with Free Riders
Broadcast encryption (BE) deals with secure transmission of a message to a group of receivers such that only an authorized subset of receivers can decrypt the message. The transmission cost of a BE system can be reduced considerably if a limited number of free riders can be tolerated in the system. In this paper, we study the problem of how to optimally place a given number of free riders in a subset difference (SD) based BE system, which is currently the most efficient BE scheme in use and has also been incorporated in standards, and we propose a polynomial-time optimal placement algorithm and three more efficient heuristics for this problem. Simulation experiments show that SD-based BE schemes can benefit significantly from the proposed algorithms.
Sharing DSS by the Chinese Remainder Theorem
A new threshold scheme for the Digital Signature Standard is proposed using Asmuth-Bloom secret sharing based on the Chinese Remainder Theorem. The proposed scheme is simple and can be used practically in real life.