Bilkent University
Department of Computer Engineering


Privacy-Preserving Data Sharing And Utilization Between Entities


Didem Demirağ
MS Student
(Supervisor: Asst. Prof. Dr. Erman Ayday)
Computer Engineering Department
Bilkent University

In this thesis, we aim to enable privacy-preserving data sharing between entities and propose two systems for this purpose: (i) a verifiable computation scheme that enables privacy-preserving similarity computation in the malicious setting and (ii) a privacy-preserving link prediction scheme in the semi-honest setting. Both of these schemes preserve the privacy of the involving parties, while performing some tasks to improve the service quality. In verifiable computation, we propose a centralized system, which involves a client and multiple servers. We specifically focus on the case, in which we want to compute the similarity of a patient's data across several hospitals. Client, who is the hospital that owns the patient data, sends the query to multiple servers, which are different hospitals. Client wants to find similar patients in these hospitals in order to learn about the treatment techniques applied to those patients. In our link prediction scheme, we have two social networks with common users in both of them. We choose two nodes to perform link prediction between them. We perform link prediction in a privacy-preserving way so that neither of the networks learn the structure of the other network. We apply different metrics to define the similarity of the nodes. While doing this, we utilize privacy-preserving integer comparison.

Keywords: Verifiable computation, link prediction, data privacy, cryptography, homomorphic encryption, security


DATE: 31 July 2017, Monday @ 10:00