On the Polling Problem for Decentralized Social Networks
Abstract:
One of the current practical, useful but sensitive topic in social networks is polling problem
where the privacy of exchanged information and user reputation are very critical. Indeed, users
want to preserve the confidentiality of their votes and to hide, if any, their misbehaviors. Recently,
Guerraoui et al. proposed polling protocols based on simple secret sharing scheme and without
requiring any central authority or cryptography system. However these protocols can be deployed
safely and efficiently provided that the social graph structure should be transformed into a ring
structure-based overlay and the number of participating users is perfect square. In this thesis,
we address the problem of deploying decentralized polling protocols for general social graphs
and how to transform these graphs in order to increase the privacy and/or accuracy properties.
First, we propose three simple decentralized polling protocols that rely on the current state of
social graphs. The two first protocols use synchronous and asynchronous models and verification
procedures to detect the misbehaving users. The third protocol is an asynchronous one that
does not require any verification procedures and contains a method for efficiently broadcasting
message under a family of social graphs satisfying what we call the m-broadcasting property.
Second, we formalize the “adding friends†problem such that we can reuse the social graphs after
some minimum structural modifications consisting in adding new friendship relations. We also
devise algorithms for solving this problem in centralized and decentralized networks. We validate
our solutions with some performance evaluations which show that our protocols are accurate,
and inside the theoretical bounds.