Keyword updatable PEKS

Abstract

Secure keyword search in the asymmetric setting, also known as public-key encryption with keyword search (PEKS), enables a receiver to search the encrypted messages with a keyword without revealing any information on the messages to the server in the store-and-forward system such as an e-mail system. To make this possible, a sender encrypts a keyword with a receiver’s public-key and tags the encrypted keyword to the messages. In the paper, we propose PEKS with keyword updatablility (KU-PEKS), where a tagged keyword can be updated upon the receiver’s request. The proposed KU-PEKS is generically constructed and provides ciphertext confidentiality and keyword-update privacy. This keyword updatability enables synonym search and/or similarity search in PEKS. We also propose a generic transformation from KU-PEKS to secure keyword search in the symmetric setting, that is the first attempt to generically construct secure keyword search in the symmetric setting providing trapdoor privacy.