Converse Bounds for Sun-Jafar-type Weak Private Information Retrieval

Fuente: arXiv
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Auteurs principaux: Anand, Chandan, Seshadri, Jayesh, Krishnan, Prasad, Kurri, Gowtham R.
Format: Preprint
Publié: 2026
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author Anand, Chandan
Seshadri, Jayesh
Krishnan, Prasad
Kurri, Gowtham R.
author_facet Anand, Chandan
Seshadri, Jayesh
Krishnan, Prasad
Kurri, Gowtham R.
contents Building on the well-established capacity-achieving schemes of Sun-Jafar (for replicated storage) and the closely related scheme of Banawan-Ulukus (for MDS-coded setting), a recent work by Chandan et al. proposed new classes of weak private information retrieval (WPIR) schemes for the collusion-free (replication and MDS-coded) setting, as well as for the $T$-colluding scenario. In their work, Chandan et al. characterized the expressions for the rate-privacy trade-offs for these classes of WPIR schemes, under the mutual information leakage and maximal leakage metrics. Explicit achievable trade-offs for the same were also presented, which were shown to be competitive or better than prior WPIR schemes. However, the class-wise optimality of the reported trade-offs were unknown. In this work, we show that the explicit rate-privacy trade-offs reported for the Sun-Jafar-type schemes by Chandan et al. are optimal for the non-colluding and replicated setting. Furthermore, we prove the class-wise optimality for Banawan-Ulukus-type MDS-WPIR and Sun-Jafar-type $T$-colluding WPIR schemes, under threshold-constraints on the system parameters. When these threshold-constraints do not hold, we present counter-examples which show that even higher rates than those reported before can be achieved.
format Preprint
id arxiv_https___arxiv_org_abs_2601_10643
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Converse Bounds for Sun-Jafar-type Weak Private Information Retrieval
Anand, Chandan
Seshadri, Jayesh
Krishnan, Prasad
Kurri, Gowtham R.
Information Theory
Cryptography and Security
Building on the well-established capacity-achieving schemes of Sun-Jafar (for replicated storage) and the closely related scheme of Banawan-Ulukus (for MDS-coded setting), a recent work by Chandan et al. proposed new classes of weak private information retrieval (WPIR) schemes for the collusion-free (replication and MDS-coded) setting, as well as for the $T$-colluding scenario. In their work, Chandan et al. characterized the expressions for the rate-privacy trade-offs for these classes of WPIR schemes, under the mutual information leakage and maximal leakage metrics. Explicit achievable trade-offs for the same were also presented, which were shown to be competitive or better than prior WPIR schemes. However, the class-wise optimality of the reported trade-offs were unknown. In this work, we show that the explicit rate-privacy trade-offs reported for the Sun-Jafar-type schemes by Chandan et al. are optimal for the non-colluding and replicated setting. Furthermore, we prove the class-wise optimality for Banawan-Ulukus-type MDS-WPIR and Sun-Jafar-type $T$-colluding WPIR schemes, under threshold-constraints on the system parameters. When these threshold-constraints do not hold, we present counter-examples which show that even higher rates than those reported before can be achieved.
title Converse Bounds for Sun-Jafar-type Weak Private Information Retrieval
topic Information Theory
Cryptography and Security
url https://arxiv.org/abs/2601.10643