Stateful Zero-Knowledge

Finanzierung: Fonds National de la Recherche > CORE > Core Junior
Anfangsdatum: 1. März 2018
Enddatum: 28. Februar 2021


A zero-knowledge (ZK) proof system allows a prover to prove statements to a verifier without revealing secret information. The goal of this project is to define, construct and analyse protocols for stateful zero-knowledge (SZK). SZK is defined as the task of keeping state information between prover and verifier in a ZK proof system. We view the state as a data structure where the prover stores each piece of data at a certain position.

Our definitions must ensure the following: (1) data in the state is hidden from the verifier, (2) the prover can read and write data at positions while hiding both the data and the positions, and (3) a piece of data read from the state at a position equals the last piece of data stored at that position.

Our constructions for SZK will allow the prover to prove statements about the positions read or written. We will use SZK as building block in protocols for data collection and analysis, which are useful to protect privacy while allowing the release of statistics about data. These protocols are of interest in a lot of settings, e.g. e-commerce, location-based services and smart metering and billing. Thanks to the strong privacy properties offered by SZK, we will be able to design protocols for tasks that before could not be realized while fully protecting user privacy.