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Table 4 Detailed computation and communication costs

From: Location-sharing protocol for privacy protection in mobile online social networks

Protocol Communication costs Computation costs
Location updation Location query Location updation Location query
Nan Shen [21] \((k\,+\,1)\lambda\) (3p + 3)\(\lambda\) k.Enc-asym + k.Dec-asym p.Enc-sym + Enc-asym + p.Dec-sym + Dec-asym
Jin Li [28] \((n\,+\,n^{2})\lambda \,+\,\mu\) \((n\,+\,n^{2}\,+\,2p)\lambda\) n.Enc-asym +  n.Dec-asym + Sig + Ver \((n\,+\,p)\).Enc-asym + (n + p).Dec-asym
Xi Xiao [30] \((k\,+\,1)\lambda\) \((2p\,+\,1)\lambda\) k.Enc-asym + k.Dec-asym \((p\,+\,1)\).Enc-asym + \((p\,+\,1)\).Dec-asym
Juan Chen [22] \((k\,+\,1)\lambda\) + 2\(\mu\) 2p\(\lambda\) + 4\(\mu\) k.Enc-asym + k.Dec-asym + Sig + Ver p.Enc-asym + p.Dec-asym + Sig + Ver
Chang Xu [29] \((2n^{2}+2n)\lambda \,+\,\mu\) (\(n^{2}\,+\,t\,+\,2p\,+\,n)\lambda\) 2n.Enc-asym + 2n.Dec-asym +Sig + Ver \((t\,+\,n\,+\,p)\)Enc-asym + \((t\,+\,p\,+\,n)\)Dec-asym
Our protocol 3\(\lambda\) + \(\mu\) \((2p\,+\,4)\lambda\) 2.Enc-asym + 2.Dec-asym + 2.Sig + 2.Ver 3.Enc-asym + p.Enc-sym + 3.Dec-asym + p.Dec-sym
  1. \(\lambda\): the length of elements calculated by elliptic curve encryption operation
  2. \(\mu\): the length of elements calculated by elliptic curve signature operation
  3. p: In the location query stage of friends and strangers, the number of members meeting the requirements of the inquirer
  4. n: the number of location services
  5. Enc-sym: a symmetric encryption operation
  6. Enc-asym: an asymmetric encryption operation
  7. Dec-sym: a symmetric decryption operation
  8. Dec-asym: an asymmetric decryption operation
  9. Sig: a elliptic curve signature operation
  10. Ver: an operation to verify the validity of an elliptic curve signature
  11. k: one real location and \((k-1)\) virtual locations generated by k anonymous
  12. t: the number of friends assigned to each location server