1. A Privacy Preserving Repository for Securing Data across the Cloud ENMING LI UIN: 00835113 EMAIL: eli@cs.odu.edu CS775 Presentation

2. Introduction & Issues  Cloud Computing – Internet-based, resource (data) distributed, computation at cloud servers.  Issues: 1. distributed data sharing owners do not want to submit ALL their private data to central computing servers, but ONLY the data needed to produce the users’ query result. 2. Data owners do not want their data to be intercepted in the course of transmission.

3. Solution  Concept of Privacy Preserving Repository  How can the Repository Increase the Privacy? 1. Extract ONLY the NECESSARY data from the data sharing service; 2. Do computation on encrypted data 3. Encrypt the final computation result

4. Architecture of the Repository

5. How the Repository Works  User send his/her public key and query to the repository  Query Plan Wrapper: make query plan scan the user’s query, figure out what intermediate results are needed for producing the final result; based on the intermediate result, break the whole query into a sequence of sub-queries in the form (p 1 ; p 2 ; _ _ _; p m );  Query Plan Executor: For each sub-query p i, look for the corresponding data sharing service S i, send pi to S i ; S i will prepare the data needed for computing, encrypt those data, then send them back to query plan executor; Compute the intermediate and final results; Encrypt the final result using user’s public key; Send back the final result to the user; Destruct all the encryped data and intermediate results that are used for computing the final result.

6. Example  Final Results: The Progress of Project with name RD  Q1->Tmp1: ID of Project RD  Q2->Tmp2: Number of Employees working on Project RD  Q3->Tmp3: Place of Project RD  Q4-> Final Result Note: The user just need to know the PROGRESS of a Given Project, so other intermediate result is encrypted by hash function.

7. Benefits of Using the Repository  Keep the privacy of user data as much as possible, by picking up only the necessary data, encrypt the intermediate result.

8. Reference  R. Mishra, S. Dash, “A Privacy Preserving Repository for Securing Data across the Cloud”