Marko Vukolic

Elli Androulaki, Angelo De Caro, Kaoutar Elkhiyaoui et al.

Traditionally, blockchain systems involve sharing transaction information across all blockchain network participants. Clearly, this introduces barriers to the adoption of the technology by the enterprise world, where preserving the privacy of the business data is a necessity. Previous efforts to bring privacy and blockchains together either still leak partial information, are restricted in their functionality or use costly mechanisms like zk-SNARKs. In this paper, we propose the Multi-Shard Private Transaction (MSPT) protocol, a novel privacy-preserving protocol for permissioned blockchains, which relies only on simple cryptographic primitives and targeted dissemination of information to achieve atomicity and high performances.

Marko Vukolic

This report summarizes the requirements and proposes a high-level solution for interoperability across recently proposed COVID-19 exposure notification efforts. Our focus is on interoperability across exposure notification (EN) applications which are based on the decentralized Bluetooth Low Energy (BLE) protocol driven by Google/Apple Exposure Notifications API (including DP3T and similar protocols). We distinguish different interoperability use cases, such as worldwide public EN interoperability, as well as interoperability in the enterprise EN systems. This report also proposes an API and a backend implementation architecture for EN interoperability. Finally, we propose using a permissioned blockchain-based solution for managing EN backend certificates and configurations (without storing any users' data on the blockchain) for helping address EN interoperability challenges across different vendors.