RPAR: Location Privacy Preserving via Repartitioning Anonymous Region in Mobile Social Network

Algorithm 1

RPAR.

Input:  , , , , , , , other users’ location information in anonymous set stored in anonymous servers.

Output: central locations and .

  form the first sub-anonymity region , and calculate its central location   and area based on , and

other user location information.

  for    to    do

 ;

select user randomly from the rest of the tail  anonymity user set  : ;

form and and calculate its central location   and area according to the information of and parameter

settings;

calculate total area of all the sub-anonymity regions: ;

  end  for

  if    then

if  then

repartition the largest sub-anonymity region until

 end  if

  else

repartition the users in the tail anonymous user set into sub-anonymity regions according to the nearest neighbor

principle

  end  if

  update the central locations  of the sub-anonymity regions

  return to all users in -th sub-anonymity region. and are sent to the LBS servers to query location

services.