CASA Distinguished Lecture with Dr. Nico Döttling

In connection with our DFG Cluster of Excellence "CASA - Cyber Security in the Age of Large-Scale Adversaries" we are pleased to announce the next dates for the CASA Distinguished Lectures. In this format, selected international and national scientists give guest lectures at the HGI.

On July 18, from 12pm-14pm Dr. Nico Döttling from CISPA Helmholtz Center for Information Security will give a lecture. In IC 03/606 he talks about "Trapdoor Hash Functions and their Applications".

Abstract: We introduce a new primitive, called trapdoor hash functions (TDH), which are compressing hash functions with additional trapdoor function-like properties. Specifically, given an index i, TDHs allow for sampling an encoding key ek (which hides i) along with a corresponding trapdoor. Furthermore, given a hash value H(x), a hint value E(ek,x), and the trapdoor corresponding to \ek, the i-th bit of x can be efficiently recovered. In this setting, one of our main questions is: How small can the hint value E(ek,x) be? We obtain constructions where the hint is only one bit long based on DDH, QR, DCR, or LWE. As the main application, we obtain the first constructions of private information retrieval (PIR) protocols with communication cost poly-logarithmic in the database size based on DDH or QR. These protocols are in fact rate-1 when considering block PIR.

About Nico Döttling: Tenure-track faculty at the Helmholtz Center for Information Security (CISPA) in Saarbrücken. The focus of his research is public key encryption and secure two-party computation. From 2017 to 2018 he was assistant professor at the Friedrich-Alexander-University Erlangen Nürnberg. Prior to that, he was a postdoc in the group of Sanjam Garg at UC Berkeley, supported by a DAAD fellowship from 2016 to 2017 and a postdoc in the crypto group of Aarhus University, working with Ivan Damgård and Jesper Buus Nielsen form 2014 to 2016. He finished his PhD in 2014 at the Karlsruhe Institute of Technology under the supervision of Jörn Müller-Quade. He is the 2014 winner of the biennial Erika and Dr. Wolfgang Eichelberger Dissertation Award.

Sandwiches and snacks will be provided.

We are looking forward to your visit! A registration is not necessary, but the seats are limited.