Security and Communication Networks

Research Article

Privacy-Preserving Query Scheme (PPQS) for Location-Based Services in Outsourced Cloud

Algorithm 1

Distance comparison algorithm.
Input: , .
Output: as TRUE or FALSE.
(1)The type retrieval cloud generates key pair by running the paillier cryptosystem and selects a random value . The public key is open to other entities;
(2)The user encrypts query radius with and then generates ;
(3)The location retrieval cloud generates random and , and then computes  =   =  for , the location retrieval cloud computes and sends to the type retrieval cloud;
(4)If and only if is found, the type retrieval cloud outputs as TRUE. Otherwise outputs FALSE.