A Quantum-Based Database Query Scheme for Privacy Preservation in Cloud Environment

Table 1

Key notations and descriptions involved in proposed QBDQ scheme.

Notation	Description
	The number of items in cloud server’s database
	The cloud server’s database,
	The i-th data in
	The number of index qubits used to encode index of data items
	The number of qubits used to encode data
	The index of client Alice’s query data
	The data item Alice wants to query from
	The index of client Bob’s query data
	The data item Bob wants to query from
	The offset value of Alice
	The offset value of Bob
	The encryption key sequence belongs to Charlie, .
	The oracle operation to encode Charlie’s key sequence
	The oracle operation to encode Alice’s query result
	The oracle operation to encode Bob’s query result
	The oracle operation which conditionally changes the sign in the amplitudes of the query item ()
	The oracle operation which perform a conditional phase shift of -1 with every computational bass state except