Dual-Source SPIR Over a Noiseless MAC Without Data Replication or Shared Randomness

Rémi A. Chou

doi:10.1109/TIT.2025.3641527

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Dual-Source SPIR Over a Noiseless MAC Without Data Replication or Shared Randomness

2026-02-01

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Rémi A. Chou *

DOI：10.1109/TIT.2025.3641527

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Abstract

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Information-theoretically secure Symmetric Private Information Retrieval (SPIR) from a single server is known to be infeasible over noiseless channels. Known solutions to overcome this infeasibility involve additional resources such as database replication, shared randomness, or noisy channels. In this paper, we propose an alternative approach for achieving SPIR with information-theoretic security guarantees, without relying on shared randomness, noisy channels, or data replication. Specifically, we demonstrate that it is sufficient to use a noiseless binary adder multiple-access channel, where inputs are controlled by two non-colluding servers and the output is observed by the client, alongside a public noiseless communication channel between the client and the servers. Furthermore, in this setting, we characterize the optimal file rates, i.e., the file lengths normalized by the number of channel uses, that can be transferred.

Keywords:

Servers

Noise measurement

Adders

Protocols

Optical transmitters

Random variables

Privacy

Information retrieval

Communication channels

Vectors

Oblivious transfer