Tree-Based Public Key Encryption with Conjunctive Keyword Search

Algorithm 5

The algorithm for building an index tree and declared by BuildTree (CurrentNodeSet).

Input: the , which contains all the leaf nodes.
Output: the plaintext index tree .
(1)	ifthen
(2)	return;
(3)	This is the root node of the tree.
(4)	end if
(5)	Initializes an empty set ;
(6)	Sets and ;
(7)	whiledo
(8)	ifthen
(9)	Creates a parent node for two nodes and , , , , , and generates according to the Algorithm 3;
(10)	Insert to ;
(11)	else
(12)	Insert to ;
(13)	end if
(14)	;
(15)	end while
(16)	;
(17)	recursive calls BuildTree (Algorithm 5).
(18)	return;