We show that for every effective left conjugacy closed left quasigroup, there is an induced rack that retains the conjugation structure of the left translations. This means that cryptographic protocols relying on conjugacy search can be secure only if conjugacy search of left translations is infeasible in the induced rack. We note that, in fact, protocols based on conjugacy search could be simp...

Electronic health record (EHR) system facilitates integrating patients' medical information and improves service productivity. However, user access to patient data in a privacy-preserving manner is still challenging problem. Many studies concerned with security and privacy in EHR systems. Rezaeibagha and Mu [1] have proposed a hybrid architecture for privacy-preserving accessing patient records...

With a significant advance in ciphertext searchability, Public-key encryption with keyword search (PEKS) is the first keyword searchable encryption scheme based on the probabilistic encryption, such that it is more secure than almost all previous schemes. However, there is an open problem in PEKS that its search complexity is linear with the sum of ciphertexts, such that it is inefficient for a...

In cloud computing, data owners are motivated to outsource their complex data management systems from local sites to the commercial public cloud for great flexibility and economic savings. But for protecting data privacy, sensitive data has to be encrypted before outsourcing, which obsoletes traditional data utilization based on plaintext keyword search. Thus, enabling an encrypted cloud data s...

Cloud computing has become fame in the society and more users and more data owners centralize their secure data into the cloud. As there is huge amount of data files that are stores in the cloud server, it is important to provide security for the cloud and for the keyword based search service to data user. Here in order to protect this data, sensitive data is usually encrypted before ending the...

The Naor-Yung (NY) paradigm shows how to build a chosen-ciphertext secure encryption scheme from three conceptual ingredients: a weakly (i.e., IND-CPA) secure encryption scheme, a replication strategy that speci es how to use the weakly secure encryption scheme; concretely, a NY-encryption contains several weak encryptions of the same plaintext, a non-interactive zero-knowledge (NIZK) proof sys...

Nowadays, more and more people are motivated to outsource their local data to public cloud servers for great convenience and reduced costs in data management. But in consideration of privacy issues, sensitive data should be encrypted before outsourcing, which obsoletes traditional data utilization like keyword-based document retrieval. In this paper, we present a secure and efficient multi-keyw...

The Naor-Yung (NY) paradigm shows how to build a chosen-ciphertext secure encryption scheme from three conceptual ingredients: a weakly (i.e., IND-CPA) secure encryption scheme, a replication strategy that speci es how to use the weakly secure encryption scheme; concretely, a NY-encryption contains several weak encryptions of the same plaintext, a non-interactive zero-knowledge (NIZK) proof sys...