Protecting Check-In Data Privacy in Blockchain Transactions with Preserving High Trajectory Pattern Utility

Algorithm 4

The location assignment based on trajectory pattern algorithm.

Input: privacy protection threshold k, generalized location type set T, trajectory pattern matrix M, sensitive location type , location queue L;

Output: generalized location type quantity array S.

1. Initialize S []=0, [1|T|];

2. S []=min (k-1, L ());

3. While <k-1 do

4.   for each location type Tdo

5.   if <=L () then

6.    ++;

7.    update M based on to change M to;

8.    Calculate;

9.    --;

10. = which maximizes ;

11. M=;

12. Return S.