Protecting Location Privacy for Outsourced Spatial Data in Cloud Storage

Algorithm 2

Index generation algorithm for DSC (IGD).

Input: quad tree root node 𝑄, starting point 𝑆₀, curve orientation 𝜃

Output: updated quad tree root node 𝑄

(1)  𝑄_𝑂←𝜃;𝑄_𝑆←𝑆₀;

(2) PUSH(𝑄,𝑆);𝑐←0;

(3)  while  𝑆≠∅  do

(4)   𝑍← POP(𝑆);

(5)   if  𝑍_𝐶≠∅  then

(6)     for  𝑖←3 to 0  do

(7)       𝑍(𝑖)_𝑂←𝑇_𝑂(𝑍_𝑂,𝑍_𝑆,𝑖);𝑍(𝑖)_𝑆←𝑇_𝑆(𝑍_𝑂,𝑍_𝑆,𝑖);

(8)       PUSH(𝑍(𝑖),𝑆);

(9)     end  for

(10)   else

(11)      𝑍_𝐷←𝑐;𝑐←𝑐+1;

(12)   end  if

(13) end  while