$ Whoami

I am Mathias Hall-Andersen (“rot256” on the internet), a PhD in theoretical cryptology (from Aarhus University) with a broad interest in both theoretical and practical information security, as well as privacy enhancing technologies including: cryptography, cryptanalysis, coding theory, reverse engineering, vulnerability research and anything which lies in the intersection. I love building and breaking real-world systems; particularly when they involve cryptography, with a soft spot for succinct arguments (SNARKs).

Together with David Wong and Gregor Mitscha-Baude I helped cofound ZKSecurity which does security auditing and engineering for advanced cryptography with a focus on zero-knowledge type applications: SNARKs, recursive proofs, anonymous credentials etc. If you are building with such technologies, or planning to build with them, you should reach out.

In my free time I play/organize CTFs with Kalmarunionen / Norsecode, I also work on open source software and enjoy various types of swing dancing. On this site I post cryptography related technical content, ideas too small for a paper, projects I have been working on and write-ups for CTF challenges (usually exploitation / reversing / cryptography challenges).

Education

Work

Research

Preprints

• Fully-Succinct Arguments over the Integers from First Principles
  Matteo Campanelli and Mathias Hall-Andersen.

• Foundations of Data Availability Sampling
  Mathias Hall-Andersen, Mark Simkin and Benedikt Wagner.

Publications

• Jackpot: Non-Interactive Aggregatable Lotteries for Asiacrypt 2024.
  Nils Fleischhacker, Mathias Hall-Andersen, Mark Simkin and Benedikt Wagner.
• Extractable Witness Encryption for KZG Commitments and Efficient Laconic OT for Asiacrypt 2024.
  Nils Fleischhacker, Mathias Hall-Andersen and Mark Simkin.
• Dora: Processor Expressiveness is (Nearly) Free in Zero-Knowledge for RAM Programs for CCS 2024.
  Aarushi Goel, Mathias Hall-Andersen and Gabriel Kaptchuk.
• FRIDA: Data Availability Sampling from FRI for Crypto 2024.
  Mathias Hall-Andersen, Mark Simkin and Benedikt Wagner.
• Curve Trees: Practical and Transparent Zero-Knowledge Accumulators for USENIX 2023.
  Matteo Campanelli, Mathias Hall-Andersen and Simon Holmgaard Kamp.
• Speed-Stacking: Fast Sublinear Zero-Knowledge Proofs for Disjunctions for Eurocrypt 2023.
  Aarushi Goel, Mathias Hall-Andersen, Gabriel Kaptchuk and Nicholas Spooner. Presentation
• On Valiant’s Conjecture: Impossibility of IVC from Random Oracles for Eurocrypt 2023.
  Mathias Hall-Andersen and Jesper Buus Nielsen. Presentation (by me)
• Efficient Proofs of Software Exploitability for Real-world Processors for PoPETs 2023.
  Matthew Green, Mathias Hall-Andersen, Eric Hennenfent, Gabriel Kaptchuk, Benjamin Perez and Gijs Van Laer.
• Automated Analysis of Halo2 Circuits for SMT 2023.
  Fatemeh Heidari Soureshjani, Mathias Hall-Andersen,
  Mohammad Mahdi Jahanara, Jeffrey Kam, Jan Gorzny, Mohsen Ahmadvand.
• Secure Multiparty Computation with Free Branching for Eurocrypt 2022.
  Aarushi Goel, Mathias Hall-Andersen, Aditya Hegde and Abhishek Jain. Presentation.
• Stacking Sigmas: A Framework to Compose Σ-Protocols for Disjunctions for Eurocrypt 2022.
  Aarushi Goel, Matthew Green, Mathias Hall-Andersen and Gabriel Kaptchuk. Presentation (by me).
• Efficient Set Membership Proofs using MPC-in-the-Head for PoPETs 2022.
  Aarushi Goel, Matthew Green, Mathias Hall-Andersen, and Gabriel Kaptchuk. Presentation.
• Count me in! Extendability for Threshold Ring Signatures for Asiacrypt 2022.
  Diego F. Aranha, Mathias Hall-Andersen, Anca Nitulescu, Elena Pagnin and Sophia Yakoubov. Presentation.
• Veksel: Simple, Efficient, Anonymous Payments with Large Anonymity Sets… for AsiaCCS 2022.
  Matteo Campanelli and Mathias Hall-Andersen. Presentation (by me)
• Game Theory on the Blockchain: A Model for Games with Smart Contracts, for SAGT 2021.
  Mathias Hall-Andersen and Nikolaj I. Schwartzbach
• Generating Graphs Packed with Paths, for IACR-FSE-2019.
  Mathias Hall-Andersen and Philip S. Vejre Presentation (by me).
• nQUIC: Noise-Based QUIC Packet Protection, for EPIQ'18 (ACM)
  Mathias Hall-Andersen, David Wong, Nick Sullivan and Alishah Chator.

Languages

Fluent in Danish, English, Rust, Python, Sage, C, Go, LaTex, a slew of assembly languages and cryptographic jargon. Shaky in a lot more…

Writing

A few examples of my technical writing:

• Blog post about WE-KZG
• Blog post about FRI proximity test. (SNARKs / coding theory)
• Blog post about git-ring. (ring signatures)
• Blog post about differential fault attacks. (hardware attacks)
• Blog post about zero-correlation linear cryptanalysis. (symmetric cryptanalysis)
• Documentation/explainer of accumulation schemes. (recursive zero-knowledge proofs)
• Blog post about Reverie. (fast zero-knowledge proofs)

Contact

Questions? Comments? Interesting projects? Need help building/breaking cryptography?

Feel free to drop me an email :)