Byzantine-Robust Private Information Retrieval with Low Communication and Efficient Decoding

Abstract

A b Byzantine-robust K-out-of-g.,"private information retrieval ((b, K,g.,")-BRPIR) scheme allows a user to retrieve any item of a database from g.,"servers, even if only K out of the g.,"servers respond and at most b out of the K responding servers provide false answers. The existing BRPIR schemes require either an exponential time decoding algorithm or a communication complexity no better than O(n1/(2k-1) k g.,"log g.,") with k=K-2b. In this paper, we show a new (b,K,g.,")-BRPIR scheme that has both a polynomial time decoding algorithm and a communication cost of g.,"•exp(O((log n)1-over 1 r (log log n) 1 overr)) for r=log (K/(2b+1)), which is more efficient when n→ ∞.