On the Security of a Code-Based PIR Scheme

TL;DR

This paper critically examines the security of the code-based CB-cPIR scheme, revealing vulnerabilities and comparing its performance to other PIR schemes, emphasizing the need for further research in code-based PIR methods.

Contribution

The paper identifies a significant security flaw in CB-cPIR and provides a comparative analysis, highlighting its limitations and the importance of exploring code-based PIR schemes.

Findings

CB-cPIR has a critical security vulnerability.

CB-cPIR's communication cost is less competitive.

Code-based PIR schemes remain a promising research area.

Abstract

Private Information Retrieval (PIR) schemes allow clients to retrieve files from a database without disclosing the requested file's identity to the server. In the pursuit of post-quantum security, most recent PIR schemes rely on hard lattice problems. In contrast, the so called CB-cPIR scheme stands out as a pioneering effort to base PIR schemes on hard problems in coding theory, thereby contributing significantly to the diversification of security foundations. However, our research reveals a critical vulnerability in CB-cPIR, substantially diminishing its security levels. Moreover, a comparative analysis with state-of-the-art PIR schemes shows that CB-cPIR's advantages are reduced, making it less competitive in terms of the communication cost. Nevertheless, our findings highlight the importance of continued research into code-based PIR schemes, as they have the potential to provide a valuable alternative to lattice-based approaches.