Outsourced Mutual Private Set Intersection Protocol for Edge-Assisted IoT

Algorithm 2

Outsourced two-party set intersection protocol.

	Inputs:
	: Set
	: Set
	Output: The intersection set , where .
	Data storage phase:
	1. and determine the number of bins, the size of bins and the two hash functions .
	2. For , , computes the two bin positions and corresponding to , and inserts into one of them. fills the bin with less than elements with dummy elements, then generates the cuckoo hash table .
	3. For , , computes the bin positions and corresponding to , and inserts into both of them. fills the bin with less than elements with dummy elements, then generates the hash table .
	Data encryption phase:
	1. calls the ElGamal threshold encryption protocol to compute the encrypted hash table , and then sends to the server in shuffled order.
	2. calls the ElGamal threshold encryption protocol to compute the encrypted cuckoo hash table , and then sends to the server in shuffled order.
	Intersection calculation phase:
	1. After the and are received, the server proceeds as follows:
	(1) computes the encrypted set intersection by bins: for , computes .
	(2) then the final encrypted intersection .
	(3) publishing ..
	2. After receiving , the users , and the server proceed as follows:
	(1) each party half-decrypts to using its private key, and then sends to the server.
	(2) then the server sends to and sends to .
	Each party fully decrypts the received other party half-decrypted intersection, and gets the plaintext intersection set .