David Balbás
¡Hola! I am David Balbás, a postdoctoral researcher in Cryptography in the Applied Cryptography Group at ETH Zürich, hosted by Prof. Kenny Paterson. I work on the design and analysis of cryptographic primitives and protocols, as well as on their applications to real-world systems.
In December 2025, I obtained a PhD from IMDEA Software Institute and Universidad Politécnica de Madrid, supervised by Prof. Dario Fiore. You can find my PhD thesis here. Previously, I obtained a MSc in Computer Science from KTH Royal Institute of Technology (Sweden) and a double BSc in Mathematics and Physics from University of Cantabria (Spain).
During my PhD, I interned in the Applied Cryptography team at Input-Output Global and at NTT Social Informatics Laboratories. Before, I worked as a Cryptography Engineer at BERTEN.
Research Interests
My research is centered around the following topics. Don't hesitate to reach out if you are interested!
More broadly, I am interested in foundational and applied cryptography, computer security and privacy. I enjoy studying, analyzing, and improving technologies that can benefit from the use of cryptographic protocols. I also have expertise in cryptographic engineering, both in software and in hardware, and in securing digital infrastructure against quantum threats.
Publications
Preprints
- Accordion: Efficient Batch Proving via Algebraic Folding
David Balbás, Anca Nitulescu, Maxime Plançon
In submission - Critical-Round Special Soundness for Multi-Round Proofs
Masayuki Abe, David Balbás, Dung Bui, Miyako Ohkubo, Zehua Shang, Akira Takahashi, Mehdi Tibouchi
In submission - ProtogaLattice: Lattice-based Algebraic Folding
David Balbás, Anca Nitulescu, Maxime Plançon
In submission - FHorgEt: A Cryptographic Solution for Secure Machine Unlearning
David Balbás, Dario Fiore, Georgios Raikos, Damien Robissout, Claudio Soriente
In submission
Conference Proceedings
- Splitting Bilinear Groups: New Translations from Composite- to Prime-Order with Applications to Batch Arguments for NP
David Balbás, Dario Fiore, Duy Nguyen
CRYPTO 2026 - Circuit-Succinct Algebraic Batch Arguments from Standard Assumptions
David Balbás, Dario Fiore, Russell W. F. Lai
SCN 2026 - Pairing-based Functional Commitments for Circuits with Shorter Parameters
David Balbás, Dario Fiore, Russell W. F. Lai
PKC 2026 - Critical Rounds in Multi-Round Proofs: Proof of Partial Knowledge, Trapdoor Commitments, and Advanced Signatures
Masayuki Abe, David Balbás, Dung Bui, Miyako Ohkubo, Zehua Shang, Akira Takahashi, Mehdi Tibouchi
EUROCRYPT 2026 - Group Key Progression: Strong Security for Shared Persistent Data
Matilda Backendal, David Balbás, Miro Haller
EUROCRYPT 2026
Check out our talk at RWC 2025! - PaXport: Privacy Pitfalls in the Spanish Age Verification System
David Balbás, Diego Castejón-Molina
RECSI 2026 - Fully-Succinct Multi-Key Homomorphic Signatures from Standard Assumptions
Gaspard Anthoine, David Balbás, Dario Fiore
CRYPTO 2024 - Modular Sumcheck Proofs with Applications to Machine Learning and Image Processing
David Balbás, Dario Fiore, Maribel González Vasco, Damien Robissout, Claudio Soriente
ACM CCS 2023
Implementation, slides. - WhatsUpp with Sender Keys? Analysis, Improvements and Security Proofs
David Balbás, Daniel Collins, Phillip Gajland
ASIACRYPT 2023
Check out our poster @ USENIX Security 2023! - Chainable Functional Commitments for Unbounded-Depth Circuits
David Balbás, Dario Catalano, Dario Fiore, Russell W. F. Lai
TCC 2023 - Cryptographic Administration for Secure Group Messaging
David Balbás, Daniel Collins, Serge Vaudenay
USENIX Security 2023 - Analysis and Improvements of the Sender Keys Protocol for Group Messaging
David Balbás, Daniel Collins, Phillip Gajland
RECSI 2022 - 2nd Best Paper Award!
Theses and Academic Projects
- Cryptography for a Verifiable World: Foundations and Applications of Succinct Proof Systems.
PhD Thesis, Universidad Politécnica de Madrid, 2025 - On Secure Administrators for Group Messaging Protocols
MSc Thesis, KTH Royal Institute of Technology, 2021 - The Hardness of LWE and Ring-LWE: A Survey
Cryptology ePrint Archive, Report 2021/1358 - A Deep Learning approach for the detection of point sources in the Cosmic Microwave Background
BSc Thesis (Physics), Universidad de Cantabria, 2019
Short conference paper @ ML4Astro 2022 - Attacks on RSA
BSc Thesis (Mathematics), Universidad de Cantabria, 2019
Teaching and Service
- I am partially funded by an FPU Grant by "Ministerio de Universidades" of the Government of Spain.
- I have been a Teaching Assistant in the courses:
- Programming II, BSc in Mathematics and Computer Science, Universidad Politécnica de Madrid. 2023, 2024.
- Algorithms and Data Structures, BSc in Data Science, Universidad Politécnica de Madrid. 2023, 2024.
- Algorithms and Data Structures, BSc in Computer Science, Universidad Politécnica de Madrid. 2023.
- Computer Security, MSc in Computer Science, KTH Royal Institute of Technology. 2020.
- I am or have been part of the Program Committee for the conferences:
- I have reviewed scientific papers for the conferences:
- CRYPTO '22, '23, '24, '25, '26
- EUROCRYPT '23, '24, '25, '26
- ACM CCS '24, '26
- ASIACRYPT '24, '25, '26
- TCC '24, '25
- PKC '25, '26, '27
- USENIX Security '26
Contact Me
- My email address is: dbalbasg (at) gmail (dot) com
- LinkedIn profile
- My CV and references are available upon request.