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

Table 4

Notations.

Notation	Description
	The total number of LBS data items
	One hash function operation
	One symmetric encryption operation
	One symmetric decryption operation
	One exponentiation operation in group
	One pairing operation in group
	One asymmetric encryption operation
	One asymmetric decryption operation
	One additive homomorphism operation in the paillier cryptosystem
	One operation of pseudo-random permutation
	One operation of pseudo-random function
	One multiplication operation in group
	One multiplication operation between a matrix and a dimensional vector
	One inner-product operation of two-dimensional vectors
	The number of edges of a polygon
	The number of data after type retrieval
	The number of data after range retrieval
	The number of data after type retrieval and range retrieval