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Colloquium

Joerg Kliewer, New Jersey Institute of Technology

Communication Efficient Secret Sharing

Date:
Time:
4:00 pm – 4:50 pm
Avery Hall
1144 T St
Lincoln NE 68508
Additional Info: AVH
Contact:
Local Host: Christine Kelley
Abstract: A secret sharing scheme is a method to store information securely and reliably. Particularly, in a threshold secret sharing scheme, a secret is encoded into n shares, such that any set of at least t_1 shares suffice to decode the secret, and any set of at most t_2 < t_1 shares reveal no information about the secret. Assuming that each party holds a share and a user wishes to decode the secret by receiving information from a set of parties; the question we study is how to minimize the amount of communication between the user and the parties. We show that the necessary amount of communication,
termed ”decoding bandwidth”, decreases as the number of parties that participate in decoding increases. We prove a tight lower bound on the decoding bandwidth, and construct secret sharing schemes achieving the bound. Particularly, we present a scheme that achieves the optimal decoding bandwidth when d parties participate in decoding, universally for all t_1 <= d <= n. We also present a scheme based on Reed-Solomon codes which is decodable with low complexity and optimal for both d=t_1 and d=n.

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