Algorithm 3 Algorithm for Gateway-independent and Gateway-assisted Trust Evaluation

Input: The trustiness of the node k $T_k$

The node u is who sends a query against suspicious node w

The forwarding ratio of the node k$Fo{r}_k$

The malicious node threshold of suspicious node w$Mal{i}_w$

The set of child nodes v

The logical inspection node l

Output: Whether the suspicious node is malicious or normal

//Collaborative inspection

gateway sends collaborative inspection response to node u

node u relay response to child nodes v except suspicious node w

for node c ∈ v do

node c collects transmission/reception information

node c reports to node u

end for

node u calculates $Fo{r}_w$ about suspicious node w

if$Fo{r}_w$ < $Mal{i}_w$ then

suspicious node w becomes malicious node

else

suspicious node w becomes normal node

end if

//Logical inspection

gateway selects node l with the highest trustiness T among 1-hop nodes of suspicious node w

gateway sends logical inspection response to node l

$count\leftarrow 0$

fori = 1 to 5 do

node l selects random interval time $t_i$

node l calculates $Fo{r}_w$ in $t_i$ seconds about suspicious node w

if $Fo{r}_w$ < $Mal{i}_w$ then

$count$++

end if

end for

if$count$ > 2 then

suspicious node w becomes malicious node

else

suspicious node w becomes normal node

end if

//Physical inspection

gateway sends physical inspection response to drone node

$count\leftarrow 0$

drone node goes to suspicious node w area

drone node collects transmission/reception information about suspicious node w

fori = 1 to 10 do

gateway calculates $Fo{r}_w$ in t seconds about suspicious node w

if $Fo{r}_w$ < $Mal{i}_w$ then

$count$++

end if

end for

if$count$ > 4 then

suspicious node w becomes malicious node

else

suspicious node w becomes normal node

end if