Asymmetry Hurts: Private Information Retrieval Under Asymmetric Traffic Constraints.

We consider the classical setting of private information retrieval (PIR) of a single message (file) out of M messages from N distributed databases under the new constraint of asymmetric traffic from databases. In this problem, the ratios between the traffic from the databases are constrained, i.e., the ratio of the length of the answer string that the user (retriever) receives from the nth databas...