Comment on “Expressive Public-Key Encryption With Keyword Search: Generic Construction From KP-ABE and an Efficient Scheme Over Prime-Order Groups”

Abstract

The public key encryption with keyword search (PEKS) scheme is a cryptographic primitive that allows a cloud server to search for a ciphertext without knowing the corresponding keyword used in the search. An expressive PEKS scheme is a variant of the PEKS scheme that supports conjunctive and disjunctive searches (expressive search). Utilising the expressive properties of an attribute-based encryption (ABE) scheme, most of the expressive PEKS schemes can be constructed from an ABE scheme. In this paper, we first give a brief review of the transformed expressive PEKS scheme by Shen et al. in 2019. Then, we present a keyword guessing attack on Shen et al.’s transformed expressive PEKS scheme and show that an adversary can correctly guess the supposedly hidden keyword.

Keywords

• Expressive PEKS
• keyword guessing
• key-policy ABE