1. Location Based Trust for Mobile User – Generated Content : Applications, Challenges and Implementations Presented By : Anand Dipakkumar Joshi USC

2. Paper  Vincent Lenders  Emmanouil Koukoumidis  Pei Zhang  Margaret Martonosi  DEPT. of Electrical Engineering  Princeton University USC

3. Agenda  Introduction  Application  Verification System for Mobile contents  Localization / Certificate Services Implementation USC

4. Introduction  Advance in Web 2.0  You Tube, Facebook, Flickr, Wikipedia, Blogger, Orkut etc ….  Advance in Gadgets  Mobiles, PDA, Camcorder, High end cameras etc ….  User generated contents  Blogs  Podcasts  Sharing of video on you tube  etc ….  Social Networking with sharing of videos, pictures, data etc …. USC

5. Introduction (cont …) YOU TUBE Content ProducerContent Consumer USC

6. Introduction (cont …)  How to trust authenticity and quality of published information ?  How to provide consumer a level of trust for the content provided by the mobile user ?  How to protect the identity and privacy of the content producer ? Protection from malicious producers Protection from malicious consumers USC

7. Introduction (cont …)  Solution :  Application of traditional identity based security.  Application of trusted geotagging service.  Benefits  Consumers know where and when the data has been actually published.  Trust relation between the content providers and consumers in this open system.  Protection from Sybil attack.Sybil attack USC

8. Application  NEWS  Photo Sharing  Distributed Sensing  Filtering Email Spam  Mapping Data  Traffic Updates USC

9. Verification System for mobile contents  Design Goals  Generality  Scalability  Retain user privacy / anonymity  Support for user’s mobility  Support for content mobility USC

10. Verification System for mobile contents (cont …)  System Overview SHA Untrusted Network Content Producer Localization / Certificate Authorities Content Consumer DLT Certificate Ask to verify certificate / CA’s public key USC

11. Verification System for mobile contents (cont …)  Trust Model  Content producers  They can verify the location from the certificate issued to them by CA.  They trust the certificate issuing authority that they do not store and revel information about the content producers and maintain their privacy and anonymity.  Content consumers  They trust the certificate issuing authority that they only issue certificate to genuine content producers.  Privacy Issues  Producer at risk of potential attack  Producer has lot of contents  Content created is not at heavily populated location.  Solution  Needs to specify the level of accuracy and anonymity for location and time values.  Accuracy of coordinates depends on privacy E.g.: blurring of coordinates and time values. USC

12. Verification System for mobile contents (cont …)  Possible Attacks  Mobility Attack  Botnet Attack Botnet Attack  Delay Attack  Mobility Considerations  Assign multiple DLT to content, allowing one to track the mobility of the content over the creation time.  Helps to know the path on which the content is captured before its delivered to content consumers. USC

13. Verification System for mobile contents (cont …)  Alternative Certificate Mechanisms SHA Untrusted Network Content ProducerContent Consumer Verify Data USC

14. Localization Service Implementation  Secure Wireless Location  Satellite Based positioning  GPS based systems to determine location  Tower localization  Use of cell phone towers to determine location.  802.11 access points  Hybrid  GPS / infer location information from past data using cell location  Used by Yahoo!‘s ZoneTagYahoo!‘s ZoneTag USC

15. Certificate Service Implementation  Certificate Authority  Centralized  Implicit trust given to central authority.  Central server is responsible for verifying the location the generator is claiming to have and issues corresponding DLT certificate.  It assumes that the content producer have an access to the server by any means.  The certificate makes possible for the authority to track him and invade his privacy.  More susceptible to denial of service attack.denial of service attack S USC

16. Certificate Service Implementation (cont …)  Certificate Authority  Decentralized  Users ask multiple devices to obtain multiple DLT certificate.  The generating device will keep track of the trustworthy level of the other nodes.  Receivers of the data query the DLT certificate source nodes to validate the data, or simply work offline if the certificate resources are known.  Here the public key is device specific and not user specific.  System more scalable than the centralized method.  Difficult to fake an authentication.  Overhead of the system is high.  Prone to Sybil attack if the community contains more fake devices.Sybil attack  To verify the certificate the receiver device must be online as well as the sender device also must be online USC

17. Certificate Service Implementation (cont …)  Certificate Authority  Community Model  Somewhat similar to distributed method.  Community of devices will vote and decide on trust level of certificates.  Multiple certificate issuers are voted on by its users.  This decides different weights and trust levels associated with them  Scheme adopted by Digg and reputation scheme in eBay.  Community gets votes on each other’s trust level.  Super Users can boast or reduce the trust level. USC

18. Conclusion  Beneficial to many applications where trust is associated with time and location.  Tagging of a content is done using location and time and not on user’s identity. Hence user privacy is maintained.  System increases the difficulty to tag the contents with false locations unless they move to that location to tag it.  Thus by limiting various attack, it proves to be a good verification service based on location and time for user generated data. USC

19. References  Paper : "Location-based Trust for Mobile User-Generated Contents: Applications, Challenges and Implementations ”, Vincent Lenders, Emmanouil Koukoumidis, Pei Zhang and Margaret Martonosi, The 9th IEEE Workshop on Mobile Computing Systems and Applications (HotMobile 2008), Feb 2008  Web Resources  http://www.flickr.com/tour/maps/ http://www.flickr.com/tour/maps/  http://www.wunderground.com/wundermap/ http://www.wunderground.com/wundermap/  http://www.wikipedia.org/ http://www.wikipedia.org/ USC

20. Questions ???