Abstract

We present a single-database computationally private information retrieval scheme with polylogarithmic communication complexity. Our construction is based on a new, but reasonable intractability assumption, which we call the Φ-Hiding Assumption (ΦHA): essentially the difficulty of deciding whether a small prime> 2 divides ϕ(m), where m is a composite integer of unknown factorization. Our result also implies the existence of two-round CS proof systems under a concrete complexity assumption. Keywords: Integer factorization, Euler’s function, Φ-hiding assumption, private information retrieval, computationally sound proofs.

Citations