Communications of the ACM
Proactive Secret Sharing Or: How to Cope With Perpetual Leakage
CRYPTO '95 Proceedings of the 15th Annual International Cryptology Conference on Advances in Cryptology
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In this paper we present a new secret-ballot multiauthority election scheme that is proactive and guarantees privacy, universal verifiability and robustness. In our scheme, a voter posts a single encrypted message as the ballot, accompanied by a non-interactive proof that it contains a valid vote. Our scheme is an efficient modification of the result by [CGS97]. The process of key recovery for decryption of votes in our scheme requires only O(r) steps, where r is the number of authorities required to decrypt the key, and the number of messages required for initial setup of the scheme is O(n), where n is the total number of authorities. The time complexity of key recovery in [CGS97] is O(rlog2r) and the complexity of number of messages is O(n2). Thus the proposed scheme is more efficient in terms of time complexity and number of messages required to be sent. We also outline a simple and elegant technique to make our scheme proactive. Our implementation results demonstrate the improved time complexity of the proposed scheme.