Combining Multi-Server and Single-Server Private Information Retrieval for Epidemiological Modelling

Bachelor Thesis


Private Information Retrieval has various applications for any sensitive lookup of data (e.g. medical or financial data), privately retrieving software updates, improving privacy-guarantees of messaging services or improving the scalability of anonymous communication protocols like TOR. However, for many use-cases both computational PIR (cPIR) [1, 2] and information-theoretic PIR (IT-PIR) [3, 4] are not efficient enough for practical use, especially for large database sizes and/or small database entries. While cPIR makes use of homomorphic encryption (HE) and suffers from high computation on the server-side, IT-PIR has large communication costs for databases with many entries.


The goal of this thesis is to implement the hybrid PIR scheme of [5] making use of both cPIR and IT-PIR (using RAID-PIR [3, 4] and further optimizations) on mobile devices and analyse the performance improvements compared to using only cPIR or only IT-PIR for different database sizes and network settings (including LTE, WiFi, and WAN).


  • Good programming skills in C/C++
  • Basic knowledge in Android development
  • At least basic knowledge of cryptography
  • High motivation + ability to work independently
  • Knowledge of the English language, Git, LaTeX, etc. goes without saying