1. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare TOWARDS A SECURE DATA SHARING PEER-TO-PEER NETWORK BASED ON GEOMETRIC AND SEMANTIC DISTANCES Authors: Ana-Delia Sâmbotin, Mugurel Ionut Andreica E-mail: delia.sambotin@gmail.com, mugurel.andreica@cs.pub.rodelia.sambotin@gmail.commugurel.andreica@cs.pub.ro 18.12.20151

2. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Outline Introduction Goals Design Architecture Experimental Evaluation Conclusion 18.12.20152

3. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Introduction P2P overlay topology in which nodes communicate one- to-one with their neighbors Resource (file) sharing Find a given resource (file) Find similar resources (files) to a given resource (file) Transfer a given resource (file) (hop-by-hop in the P2P topology) Security –Data transfer encryption –Anonymization –Avoid traffic analysis 18.12.20153

4. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Goals Similarity search based on implicit user attributes (i.e. extracted automatically, not explicitly expressed by the users) Better chances of finding a given resource (similar resources) quickly when using bounded flooding for search) Good data transfer performance (e.g. data transfer speed) Security and privacy (encryption, anonymization, etc.) 18.12.20154

5. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Design Each peer computes a set of coordinates in a D-dimensional space, based on: –Network round-trip time (RTT) –Semantic distance (i.e. similarity of resources to other peers) In a distributed manner, each peer will select as neighbors in the topology other peers with small distances to it (based on the distance in the geometric space) –Network RTT => good data transfer performance in hop-by-hop data transfers –Semnatic closeness => good chance of finding a given resource (file) or similar resources (files) nearby (among its neighbors or at most a given distance R away from it) 18.12.20155

6. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Architecture Main modules related to: –Network communication (low- level) –P2P topology construction and maintenance –Data transfer –Resource (file) search –Security 18.12.20156

7. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Architecture Two main roles: Bootstrap node and normal node The nodes will first contact the bootstrap nodes in order to find a set of nodes already in the system; afterwards, they organize themselves Different types of strategies for constructing the P2P overlay 18.12.20157

8. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Strategies for the P2P overlay A network of “supernodes”, that “hide” a group of peers A “supernode” can be considered to be a “proxy” node Geometric coordinates computed based on network abd semantic distances between a peer and a subset of other peers (Resource or Similarity) Search strategy – bounded (distance) flooding 18.12.20158

9. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Architecture - formulas Network distance metric Semantic distance (based on the common resources) 18.12.20159

10. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Security Module Anonymization: using mediators Avoiding traffic analysis –Dummy search terms in a search query –Dummy search queries Encryption of data transfers using public/private keys

11. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Evaluation – Distance metrics Evaluation (through simulation) of peer distribution in 2D when: (c) –Using only the network distance (a) –Using only the semantic distance (b) –Using a combination of both metrics (c) (a) (b)

12. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Evaluation – Using Mediators Duration of a search query: –Secure (encrypted messages) with mediator –Secure (encrypted messages) without mediator –Unsecure (without mediator) Encryption slows things down (up to 30%-35%) Using a mediator does not have a meaningful negative impact on performance

13. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare Conclusions Proposed a P2P-based data sharing system with: –Enhanced security attributes (anonymization and encryption) –A combination of network distance (RTT) and semantic distance for building the overlay Experimental results are promising 18.12.201513

14. Universitatea Politehnica Bucureşti - Facultatea de Automatică şi Calculatoare The end Thank you! Questions? 18.12.201514