A Minimum Defense Cost Calculation Method for Attack Defense Trees

Algorithm 2

Calculation of the minimum defense cost of ADTrees.

	Input A2DTree
	Output The minimum defense cost of the A2DTree and the set of attack nodes that need to be defended
(1)	BooleanExpression: = A2DTree logical expression;
(2)	PathSets: = {All simple conjunctions in BooleanExpression, that is, the set of all path sets of the A2DTree};
(3)	MinCost: = ;
(4)	PathSet: = {};
(5)	j: = 1;
(6)	repeat
(7)	pathset: = jth path set in PathSets;
(8)	cur_cost:= Cut-set defense cost;
(9)	if cur_cost < MinCost
(10)	then
(11)	MinCost: = cur_cost;
(12)	PathSet: = pathset;
(13)	end if
(14)	j: = j + 1;
(15)	until j = Number of subsets in PathSets +1;