A Privacy-Preserving Trajectory Publication Method Based on Secure Start-Points and End-Points

Algorithm 1

The generation of secure start- and end-points.

	Input: user’s trajectory dataset U. number of blocks ;
	Output: a set of secure points SL.
(1)	Divide the user activity area into ;
(2)	; / time periods/
(3)	Get all points from U and partition them into different blocks;
(4)	for i  1 to do
(5)	ts  timestamps of all the points in ;
(6)	if (!isempty (ts))
(7)	Partition timestamps in ts into different time period of TPS and obtain the set ;
(8)	Sort by the number of timestamps within each time period in ascending order;
(9)	in ;
(10)	end if
(11)	if (isempty (ts))
(12)	Mark as an unreachable area;
(13)	continue;
(14)	end if
(15)	within ;
(16)	end for
(17)	return ;