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APPLAUS: A Privacy-Preserving Location Proof Updating System for Location-based Services

APPLAUS: A Privacy-Preserving Location Proof Updating System for Location-based Services. Zhichao Zhu and Guohong Cao Department of Computer Science and Engineering The Pennsylvania State University, University Park, PA 16802 {zzhu, gcao}@cse.psu.edu. outline. Introduction Preliminaries

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APPLAUS: A Privacy-Preserving Location Proof Updating System for Location-based Services

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  1. APPLAUS: A Privacy-Preserving Location Proof Updating System for Location-based Services Zhichao Zhu and Guohong Cao Department of Computer Science and Engineering The Pennsylvania State University, University Park, PA 16802 {zzhu, gcao}@cse.psu.edu

  2. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  3. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  4. Introduction Location-based Services User location information Provide mobile users with a unique style of resource and services

  5. Target: • collecting a set of location proofs for each peer node. • protecting the location privacy of peer nodes from each other, from adversary.

  6. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  7. Preliminaries Pseudonym Online Certification Authority Mobile node i with a set of M public/private key pairs . KiPub serve as the pseudonyms of node i. Kiprv enable node i to digitally sign messages.

  8. Threat Model • Target: track the location of mobile nodes. • The adversary is internal, passive and global. • Internal • Passive • Global

  9. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  10. The Location Proof Updating System Architecture Protocol Scheduling Location Proof Updates

  11. Architecture Prover Witness Server CA Verifier

  12. Protocol

  13. Protocol • (1) The prover broadcasts a location proof request through Bluetooth interface. • (2) The witness decides whether to accept the location proof request. • (3) the prover is responsible for submitting this proof to the location proof server.

  14. Protocol • (4) An authorized verifier can query the CA for location proofs of a specific prover. • (5) The location proof server only returns hashed location rather than the real location to the CA, who then forwards to the verifier.

  15. Scheduling Location Proof Updates

  16. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  17. Source Location Privacy • Definition 2: source location unobservability. • Identity I, observation O • ∨ O, P(I) = P(I|O), the I is called unobservable.

  18. Source Location Privacy • Obviously, a system satisfies source location unobservability if and only if it has the property of pseudonym unlinkability.

  19. Source Location Privacy

  20. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  21. Performance Evaluation • Prototype Implementation • Simulation results

  22. Prototype Implementation • Client: JAVA, Android Developer Phone, Android 1.6 OS. • Server: C++, T4300 2.1GHz 3GB RAM laptop.

  23. Prototype Implementation

  24. Prototype Implementation

  25. Prototype Implementation

  26. Simulation results • 1000 mobile nodes • 3km * 3km area • Each node has M=10 pairs of 128-bit public/private keys • Intervalproof: the required interval between two location proof updates. • Intervalcontact: the mean real contact interval.

  27. Simulation results Message overhead ratio: the ratio of dummy traffic and real proof traffic.

  28. Simulation results Proof delivery ratio: the percentage of location proof message that successfully uploaded to the location proof server.

  29. Simulation results Average delay: the time difference between the time when a location proof update is needed and when the location proof message has reach the location proof server.

  30. outline Introduction Preliminaries The Location Proof Updating System Security Analysis and Countermeasures Performance Evaluation Conclusions

  31. Conclusions • This paper proposed a privacy-preserving location proof updating system, called APPLAUS. • It uses statistically changed pseudonyms for each device to protect source location privacy. • Extensive experimental and simulation results show that APPLAUS can provide location proofs effectively while preserving the source location privacy at the same time.

  32. Thank you!

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