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

Table 1

Summary of notations.

Notation	Description
	A location coordinate
	The distance from to
	A data item
	The identifier of a data item
	A user
	Keywords related to POI types
	Description of a data item
	A pseudo-random function, i.e., PRF
	A pseudo-random permutation, i.e., PRP
	A symmetric encryption algorithm, AES
	Key pair generated by the paillier cryptosystem
	A user’s key pair generated by RSA algorithm
	An original query
	A symmetric encryption algorithm, i.e., AES
	A hash function
	A query radius