Bilkent University
Department of Computer Engineering


Privacy-Preserving Data Sharing and Utilization between Entities


Didem Demirağ
MS Student
Computer Engineering Department
Bilkent University

Verifiable Computation protocols help a client with limited computational capacity to outsource a computation to another party. In these protocols, concerns about privacy arise. Hence, the server needs to provide a proof that it made the correct calculation and the client should be able to verify this easily. Verification should take less effort than actually doing the computation. In our research, our main concern is maintaining privacy when storing, sharing and analyzing personal information. Service providers (SP) can analyze their own databases without any problem. However, when they want to analyze other similar SPs to provide better service, privacy of the parties in the protocol should be considered. Thus, we propose two protocols that are privacy-preserving under malicious setting. We offer centralized and distributed solutions for the proposed problem.

In distributed solution, client makes a query to one of the servers. The server prepares the result of the query along with its proof and it sends them to the next server. This server verifies them and does the same computation. It adds the new result to the previous result and creates a proof over those results. This process goes on until the result and the proof reach the client.

In centralized solution, we have a proxy to collect and verify all of the proofs. Client sends his query to proxy and then the proxy sends the query to these servers. Proxy collects the results and the corresponding proofs from the servers. It verifies all of the proofs and then creates one proof based on all of the data it received from the servers. Proxy verifies all of the results it received from the servers and generates only one proof corresponding to the results. Proxy sends the results and the proof to the client. In both solutions, the client will verify only one proof.


DATE: 31 October, 2016, Monday @ 17:00