Main Content

Privacy-Preserving Content-Based Routing in Software-Defined Networks

Author: Jannik Alexander Lange

Supervisors: Prof. Dr. Boris Koldehofe, Dr.-Ing. Peter Amthor

Format: Master's thesis, TU Ilmenau

Publish/Subscribe systems are highly scalable asynchronous messaging systems with many use cases, some of which require confidentiality and privacy of the information of the publishers, subscribers, and the message contents. In this thesis, we develop a scheme for privacy preserving content based routing on the foundation of a software defined networking implementation of a publish/subscribe system. The design has a data center environment with a fat tree topology as the reference use case in mind. The confidentiality of the information in the message headers has been achieved using encryption of addresses through bit permutation. The confidentiality of the payload has been addressed with a key management scheme for symmetric encryption that preserves the decoupling between sender and receiver, which is typical of the publish/subscribe pattern. The security of the scheme has been evaluated with a model of honest but curious adversaries and the possibility of collusion between them. Some configurations of colluding adversaries are able to compromise the security goals. Large keys and therefore large addresses are necessary to ensure sufficient resistance against brute force attacks. The key factor in scaling the system has been identified as the number of required forwarding table entries. Although good scaling was observed for a fixed address length with an increasing number of subscriptions, increasing address lengths lead to exponential increases in the forwarding table entry count.

Completed: 20.11.2025

References: https://bibliographie.tu-ilmenau.de/servlets/DozBibEntryServlet?mode=show&id=ilm_mods_00079058