A novel hybrid private information retrieval with non-trivial communication cost

All the existing replicated database Private Information Retrieval (PIR) schemes have failed to achieve 1) Breaking the dependency of both user privacy and data privacy on a single intractability assumption 2) Maintaining information-theoretically secure queries even on colluding and 3) Non-trivial server communication cost 4) Verifying the integrity of the communicating information. In this paper, we have introduced a computationally bounded 2-database colluding resistant information-theoretic private information retrieval scheme with non-trivial communication cost. Since intractability assumption independent user privacy, colluding resistant information-theoretically secure query generation and the non-trivial communication have been involved in the proposed scheme, we coin the proposed scheme as Hybrid Private Information Retrieval (hPIR). In this, colluding resistant information-theoretically secure query generation (to preserve user privacy) is achieved by extending from quadratic residuosity property dependent index inputs to quadratic residuosity property independent index inputs and non-trivial communication is achieved by a new quadratic residuosity based recursive 2-bit encryption method (to preserve data privacy). Note that the generation of colluding resistant information-theoretically secure query supports user privacy whereas application of recursive 2-bit encryption method supports both data privacy and non-trivial communication.