SECURE CLOUD STORAGE WITH KEYWORD SEARCH AND DUAL-SERVER PUBLIC-KEY ENCRYPTION

Abstract

A growing number of individuals are turning to searchable encryption to safeguard the
privacy of their data in secure cloud storage environments. In this study, we investigate the
security of public key encryption with keyword search (PEKS), a fundamental cryptographic
technique widely utilized in cloud storage applications. Unfortunately, the traditional PEKS
framework has been found to suffer from a vulnerability known as an inside keyword guessing
attack (KGA), which can be exploited by a malicious server. To address this security flaw, we
propose the dual-server PEKS framework (DS-PEKS) as a novel approach. Additionally, we
introduce a new type of smooth projective hash function (SPHF) called a linear and homomorphic
SPHF (LH-SPHF). Leveraging LH-SPHF, we present a generic construction of secure DS-PEKS.
Furthermore, we offer an effective instantiation of this general framework based on Decision
Diffie-Hellman LH-SPHF, demonstrating its ability to achieve robust security against inside KGA
attacks.