Effective Protection of Sensitive Metadata in Online Communication Networks

Bachelor Thesis


Marco Holz


While great effort has been put into securing the content of messages transmitted over digital infrastructures, practical protection of metadata is still an open research problem. Scalable mechanisms for protecting users' anonymity and hiding their social graph are needed. One technique is private information retrieval (PIR), an active field of research that enables private querying of data from a public database without revealing which data has been requested and a fundamental building block for private communication.


The goal of this thesis is to improve the multi-server scheme RAID-PIR (ACM CCSW'14) by precomputing queries using the Method of four Russians and optimizing the database layout for parallel queries.

By building and evaluating a prototype of an anonymous messaging service as an example application for PIR combined with onion routing that prevents the leakage of communication meta-data, practicality of the protection mechanisms should be demonstrated.