Michele Orrù

I believe that privacy is a human right and that cryptography can help foster an open society. My research seeks to build authentication mechanisms that preserve user anonymity. I work on:

improving efficiency and security of zero-knowledge proofs,
lightweight anonymous credential systems,
confidential transactions.

In the past, I contributed to Python, Debian, and Tor. I co-designed Globaleaks, an open-source whistleblowing platform now translated in more than 90 languages and used by more than 300 organizations, and co-authored the cryptography behind Google’s Trust Tokens. Sometimes, I help NGOs on matters of digital security.

I am a chargé de recherche (Assistant Professor) at CNRS. Previously, I have been at UC Berkeley as research scholar. I got my PhD from École Normale Supérieure, and my MSc in math from the University of Trento. I attended the Recurse Center in Fall 2020 (W2’20).

Publications

Revisiting keyed-verification anonymous credentials [ePrint],
To appear.
Oblivious issuance of proofs [ePrint],
with S. Tessaro, G. Zaverucha, C. Zhu. CRYPTO 2024.
zk-Bench: A Toolset for Comparative Evaluation and Performance Benchmarking of SNARKs [ePrint],
with J. Ernstberger, S. Chaliasos, G. Kadianakis, S. Steinhorst, P. Jovanovic, A. Gervais, B. Livshits. SCN 2024.
Non-interactive Mimblewimble transactions, revisited [ePrint],
with G. Fuchsbauer. ASIACRYPT 2022.
Gemini: an elastic proof system for diverse environments [ePrint] [Talk] [Code],
with J. Bootle, A. Chiesa, Y. Hu. EUROCRYPT 2022.
Publicly verifiable anonymous tokens with private metadata bit [ePrint],
with F. Benhamouda, T. Lepoint, M. Raykova.
A proposal for the standardization of ∑-protocols [PDF] [Talk],
with S. Krenn. 4th ZKProof Workshop.
On the (in)security of ROS [ePrint] [Talk],
with F. Benhamouda, T. Lepoint, J. Loss, M. Raykova. EUROCRYPT 2021. Best paper award! Invited to the Journal of Cryptology.
Efficient Anonymous Tokens with Private Metadata Bit [ePrint] [Talk] [Code],
with B. Kreuter, T. Lepoint, M. Raykova. CRYPTO 2020.
Aggregate cash systems: A cryptographic investigation of Mimblewimble [ePrint] [Talk],
with G. Fuchsbauer, Y. Seurin. EUROCRYPT 2019.
Lattice-Based zk-SNARKs from SSPs [ePrint] [Talk] [Code],
with R. Gennaro, M. Minelli, A. Niţulescu. ACM CCS 2018.
Non-Interactive Zaps of Knowledge [ePrint],
with G. Fuchsbauer. ACNS 2018. Best student paper!
Homomorphic Secret Sharing: Optimizations and Applications [ePrint],
with E. Boyle, G. Couteau, N. Gilboa, Y. Ishai. ACM CCS 2017.
Actively Secure 1-out-of-N OT Extension with Application to Private Set Intersection [ePrint],
with E. Orsini, P. Scholl. CT-RSA 2017.

Code

I am actively involved in maintaining the arkworks.rs algebra crate. My recent contributions include:

zka.lc: Think of this as a calculator for the concrete performance of public-key cryptography operations. You add items to your shopping list and zkalc gives you the total time at the checkout.
tinybear: proving knowledge an AES-encrypted message using Schnorr proofs in 30 milliseconds and 80KB.
nimue: a dedicated library for transforming interactive cryptographic protocols into non-interactive ones (the Fiat-Shamir transform), streamlining security processes.