Information-Theoretic Authenticated PIR: From PIR-RV To APIR
Pengzhen Ke, Yuxuan Qin, Liang Feng Zhang
TLDR
This paper introduces information-theoretic Authenticated PIR (itAPIR) with statistical privacy and integrity, enabling quantum-resistant private information retrieval.
Key contributions
- Defined rigorous information-theoretic security for itAPIR, including statistical privacy and integrity.
- Formalized itAPIR's hierarchical relation to itPIR-RV, a relaxed variant with basic query privacy.
- Proved a conversion theorem to upgrade itPIR-RV schemes to secure itAPIR with no extra overhead.
- Enables quantum-resistant private information retrieval in malicious server environments.
Why it matters
This work addresses the critical need for unconditionally secure Authenticated Private Information Retrieval (APIR). By providing a rigorous definition and a conversion theorem, it simplifies the design of robust APIR schemes. This advancement is crucial for developing quantum-resistant PIR systems that can withstand malicious servers.
Original Abstract
Private Information Retrieval (PIR) allows clients to retrieve database entries without leaking retrieval indices, yet malicious servers seriously compromise retrieval correctness. Existing Authenticated PIR (APIR) schemes resist selective-failure attacks but rely on computational hardness assumptions. In contrast, information-theoretic PIR with Result Verification (itPIR-RV) achieves integrity without computational assumptions, yet only provides relaxed query privacy with no defense against selective-failure attacks. This paper focuses on unconditionally secure information-theoretic APIR (itAPIR) constructions. We propose the rigorous information-theoretic security definition for itAPIR with statistical privacy against selective-failure attacks and integrity as core properties, formalize the hierarchical relation between itAPIR and itPIR-RV as a relaxed variant with identical integrity but basic query privacy, and prove a conversion theorem that valid itPIR-RV schemes can be directly upgraded to secure itAPIR with no extra overhead. Our work bridges the theoretical gap, simplifies itAPIR design, and enables quantum-resistant PIR in malicious server environments.
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