Hua Sun

The capacity of private information retrieval with colluding databases

Private information retrieval (PIR) is the problem of retrieving as efficiently as possible, one out of K messages from N non-communicating replicated databases (each holds all K messages) while keeping the identity of the desired message index a secret from each individual database. T-private PIR is a generalization of PIR to include the requirement that even if any T of the N databases collude, the identity of the retrieved message remains completely unknown to them. The information theoretic capacity of T-private PIR (equivalently, the reciprocal of minimum download cost) is the maximum number of bits of desired information that can be privately retrieved per bit of downloaded information. We show that the capacity of T-private PIR is (1 + T/N + T²/N² + … + T^K-1/N^K-1)⁻¹.

The Capacity of Private Information Retrieval

In the private information retrieval (PIR) problem a user wishes to retrieve, as efficiently as possible, one out of

Genie chains and the degrees of freedom of the K-user MIMO interference channel

K

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messages from

Topological interference management with alternating connectivity

N

Index Coding Capacity: How Far Can One Go With Only Shannon Inequalities?

non-communicating databases (each holds all

Private information retrieval from MDS coded data with colluding servers: Settling a conjecture by Freij-Hollanti et al

K

On the Optimality of Treating Interference as Noise: General Message Sets

messages) while revealing nothing about the identity of the desired message index to any individual database. The information theoretic capacity of PIR is the maximum number of bits of desired information that can be privately retrieved per bit of downloaded information. For

Degrees of Freedom of MIMO

K

X

messages and