News & Events
Here we are giving you a peek into what keeps us busy, motivated and happy day in and day out.
Applied Crypto @ RWC 2025 Taipei
Our group as once again a strong presence at the Real World Crypto Symposim, with 5 accepted talks in the program. Find us at RWC to hear about:
- "Signal Lost (Integrity): The Signal App is More than the Sum of its Protocols", by Kien Tuong Truong, Noemi Terzo, Peter Schwabe, Kenny Paterson, in collaboration with Max-Planck Institute for Security and Privacy.
- "SecureDrop Next Generation: Lessons from a Decade of Deployment", by Giulio Berra, Felix Linker, Luca Maier, Cory Francis Myers, Kenny Paterson, Rowen Shane, Shannon Veitch, in collaboration with ETH's Information Security group and the Freedom of the Press Foundation.
-" XHMQV: Better Efficiency and Stronger Security for Signal's Initial Handshake based on HMQV", by Rune Fiedler, Felix Günther, Jiaxin Pan, Runzhi Zeng, Rolfe Schmidt, in collaboration with IBM Research Europe – Zurich, University of Kassel and Signal Messenger.
- "Finding Bugs and Features Using Cryptographically-Informed Functional Testing", by Giacomo Fenzi, Jan Gilcher, Fernando Virdia, in collaboration with EPFL and the University of Surrey.
- Stay tuned for the title of our last talk, featuring research by Matilda Backendal, Kenny Paterson, Matteo Scarlata and Giovanni Torrisi.
19.12.2025
Cryptographic Authenticated Dictionaries @ NDSS 2026
Congratulations to Francesca Falzon for her paper "SoK: Cryptographic Authenticated Dictionaries", together with Harjasleen Malvai, Andrew Zitek-Estrada, Sarah Meiklejohn and Joseph Bonneau, which was accepted at NDSS 2025.
This work systematizes authenticated dictionaries (ADs), used in applications like key transparency and verifiable stores. It presents a framework for understanding trust and threat assumptions, clarifies security definitions, and categorizes AD constructions. The study highlights a trade-off: known schemes either offer O(logn) time for both lookups and updates or O(1) for one at the cost of O(n) for the other. It also questions the idea that more trust improves efficiency and explores research on auditing models and incentives for verifiable integrity systems.
15.12.2025
TAPIR: A Two-Server Authenticated PIR Scheme with Preprocessing @ ACNS 26
Congratulation to Francesca Falzon, Laura Hetz and Annamira O'Toole for their accepted paper at ACNS 2026.
Tapir is the first two-server Authenticated Private Information Retrieval (APIR) scheme that achieves sublinear communication and computation complexity, supporting dates and database edits/appends with preprocessing in time linear to the database partition size. It builds on the unauthenticated SinglePass scheme and offers different trade-offs based on the vector commitment used. Tapir is highly efficient, with a minimal online bandwidth overhead of 0.11% for large databases, and outperforms prior multi-server APIR schemes in terms of runtime, particularly when using Merkle trees.
15.12.2025
Fast Polynomial Hash Functions and Cryptographically-Informed Functional Testing @ TCHES 26
Congratulations to Jan Gilcher for his two accepted submission to TCHES '26 (vol 1, to appear):
- SPHGen: A Program Generator for Fast Polynomial Hash Functions, together with Tommaso Pegolotti, Kenney Paterson and Markus Püschel (ETH Zürich). SPHGen is a program generator for optimizing polynomial hash functions like poly1305. It produces efficient code for different vector ISAs (e.g., AVX2, AVX512) and ensures correctness through symbolic execution. SPHGen helps identify optimal security-performance trade-offs and predicts runtime without executing code. Benchmarks show it outperforms previous non-vectorized implementations and achieves up to 37% speedup over OpenSSL's assembly-optimized poly1305 for large messages.
- Finding Bugs and Features Using Cryptographically-Informed Functional Testing, together with Giacomo Fenzi (EPFL) and Fernando Virdia (University of Surrey). This work extends the post-mortem approach of Mouha et al. (2018) to key encapsulation mechanisms (KEMs) and digital signature schemes (DSSs), applying it to multiple versions of the LibOQS collection of post-quantum cryptographic schemes. The approach, which tests implementations for cryptographic property violations, uncovers various bugs, including software issues (e.g., segmentation faults) and cryptographic flaws like ciphertext malleability in KEMs. The study also highlights some counter-intuitive features that don’t contradict security guarantees. Compared to traditional fuzzing, the approach is more effective at identifying software and logical bugs.
15.12.2025
Welcome Rune!
Rune Fiedler joins the Applied Cryptography group as a postdoctoral researcher on 1 November 2025.
Rune obtained his PhD at Technische Universität Darmstadt, supervised by Marc Fischlin. In his PhD, he analyzed and suggested improvements for Signal's initial handshake, with focuses on post-quantum security and deniability. Furthermore, he studied security properties of signature schemes beyond unforgeability (BUFF for short - Beyond UnForgeability Features). Rune is interested in further studying the security of Secure Messaging.
Rune, welcome to the group! We look forward to working with you.
27.10.2025
Welcome Mara!
Mara Mihali joins the Applied Cryptography group as a doctoral student on 1 November 2025.
Mara earned her Master’s degree in Information Security from University College London in 2022, where her research centered on Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge (zk-SNARKs), in collaboration with Protocol Labs. After graduation, she continued her work with Protocol Labs and served as a Cryptography Engineer at Aztec Labs, where she became one of the core contributors to their proving system. She is excited to move closer to the Swiss Alps and take a leap into the research world.
Welcome to the group, Mara. We look forward to working with you.
27.10.2025
Congratulations to Matilda on a great Defence!
We are delighted to announce that our friend and colleague, Matilda Backendal, successfully passed her doctoral exam on 2 October 2025. Her thesis is titled “Thriving in between theory and practice: Case studies in provable security.”
This represents the final step in the journey of Matilda's doctoral studies, which started in 2018, when the Applied Cryptography group had just formed at ETH. Throughout the years, Matilda helped to shape the group and our community to what it is today. Not only was she extraordinarily dedicated and passionate about her job, but she also invested countless hours working with VMI to organize social events for students, to promote and lead mental health initiatives, and to raise awareness and extend the support network for women in computer science. She has been instrumental in fostering a cohesive and supportive environment for all, ensuring that everyone feels valued and appreciated.
We are proud of Matilda's accomplishments and excited to see the impact she will continue to make in her field.
Join us in celebrating Matilda's success and wishing her all the best as she embarks on the next chapter of her career.
02.10.2025
Welcome Àlex!
We are happy to announce that Àlex Rodríguez Garcia is joining our group as a project mobility student from 15 September 2025 to 29 May 2026. Àlex spent time with us last summer as a visiting student as part of the ETH Summer Research Fellowship programme, and we look forward to having him back. He comes from Universitat Politècnica de Catalunya (UPC), Barcelona, for his final degree project of the Centre de Formació Interdisciplinària Superior's (CFIS) study programme in mathematics and data science. He will be working on cryptanalysis of hash functions. As a mobility student, Àlex aims to enhance his knowledge and skills, while also sharing his own perspectives and experiences with our group. His academic achievements and passion for his work make him a valuable addition to our community.
We encourage everyone to extend a warm welcome to Àlex and support him throughout his journey at ETH Zurich.
Great to have you back Àlex!
04.09.2025
Congratulations to Mia Filić on Passing the Doctoral Exam!
We are delighted to share that our colleague, Mia Filić, successfully passed her doctoral exam. Her thesis is titled "Probabilistic Data Structures in Adversarial Settings."
Throughout her journey, Mia showed unwavering dedication and a collaborative spirit that inspired us all. Her ideas and sometimes unconventional approach have significantly enriched our group, hugely contributed to make this a warm and friendly place, and challenged us to think creatively.
Please join us in celebrating this wonderful achievement. We’re sad to see Mia go, but are eager to see where her career will lead and wish her all the very best for her future endeavours.
Congratulations, Mia!
20.08.2025
Applied Crypto at CCS 2025
Two of our papers will appear at CCS this autumn in Taipei!
- Sabot: Efficient and Strongly Anonymous Bootstrapping of Communication Channels. by Christoph Coijanovic, Laura Hetz, Kenny Paterson, Thorsten Strufe.
Sabot bridges a gap in anonymous communication, providing a bootstrapping protocol that achieves both strong cryptographic privacy guarantees and bandwidth-efficient communication. - Breaking and Fixing Content-Defined Chunking, by Kien Tuong Truong, Simon-Philipp Merz, Matteo Scarlata, Felix Günther, Kenny Paterson.
This work takes a look at the leakage resulting from algorithms used to split large amount of data into smaller chunks. Folklore methods for reducing this kind of leakage had not been analyzed before -- and they turn out to all be vulnerable to attacks. The authors also propose a provably secure chunking algorithm.
14.08.2025
Kenny Paterson gives an invited talk at ArcticCrypt 2025.
Kenny was invited to give a talk at ArcticCrypt 2025, held in Longyearbyen, Svalbard this week. Svalbard is located inside the Arctic circle and enjoys 125 days of continuous daylight during the summer. Kenny’s talk with title “Living in a Parallel Universe: the Quantum Internet and Quantum Key Distribution” was delivered in a “midnight” session at the conference starting at 12:15am on Tuesday 8th July. Kenny was able to keep his audience awake with a talk exploring the promise of, and challenges faced in achieving the vision of, the Quantum Internet.
10.07.2025
Welcome Martin!
Martin Hirt joins the Applied Crypto group as a Senior Scientist on 1 August 2025.
Martin did his Master's and PhD at ETH. His current research areas are multi-party computation, Byzantine agreement, and efficiency of secure protocols. Martin was awarded the VSETH Golden Owl in 2017 and the TCC test of time award in 2020. We are looking forward to welcoming Martin to the group, where his expertise in foundational aspects of cryptography and his extensive teaching experience will be highly valued.
07.07.2025
EPFL-ETH Summer School on Lattice-based Cryptography
The summer school on Lattice-based Cryptography has recently concluded.
PhD and Master's students from ETH and EPFL attended the school, which covered topics ranging from the fundamental hardness assumptions of lattices, to lattice-based signatures and encryption, and advanced schemes such as FHE.
The programme featured invited talks from Fernando Virdia, Vadim Lyubashevsky, Gregor Seiler, Jonathan Bootle, Christian Mouchet, Akin Ünal and Lena Heimberger.
The summer school was organized by Christian Knabenhans (EPFL, COMPSEC and SPRING labs), Shannon Veitch (ETH Zurich, Applied Cryptography group), and Dr. Jonathan Bootle (IBM Research Zurich), with support from Prof. Alessandro Chiesa (EPFL) and Prof. Kenny Paterson (ETH Zurich).
12.07.2025
Best Paper Award at CODASPY 2025
Congratulations to Mia Filić and Kenny Paterson for winning a best paper award at CODASPY 2025 for their paper entitled “Probabilistic Data Structures in the Wild: A Security Analysis of Redis”. The paper resulted from a collaboration with Jonas Hofmann (formerly a Master’s student with the Applied Cryptography group, now a doctoral student at TU Darmstadt), Sam Markelon (PhD student at the University of Florida, and previously a visitor to the group thanks to a ThinkSwiss Research scholarship), and Dr. Anupama Unnikrishnan (formerly a postdoc with the group, now Executive Director of the ETH Quantum Center). The paper provides a detailed security analysis of Probabilistic Data Structures (PDS) supported in the Redis in-memory database system in adversarial settings, presenting a total of 10 attacks against the PDS in Redis, as well as proposing countermeasures to the attacks.
Read the full version of the paper here: external page https://eprint.iacr.org/2024/1312.
01.07.2025
Applied Crypto at Crypto '25 Santa Barbara
The paper "Hybrid Obfuscated Key Exchange and KEMs", by Felix Günther, Michael Rosenberg, Douglas Stebila and Shannon Veitch, was accepted at Crypto.
The work presents an OKEM combiner that achieves hybrid IND-CCA security with hybrid ciphertext obfuscation guarantees, leading to the development of Drivel, a modified pq-obfs protocol compatible with hybrid OKEMs. This enables practical implementations, such as combining obfuscated versions of DHKEM and ML-KEM, and provides the first hybrid PAKE protocol secure against adaptive corruptions in the UC model.
20.06.2025
CAW 2025 Recordings Now Online
Recordings of our CAW sessions are now online (thank you Miro!). If you missed our workshop and are curious about the talks, you can find them external page here!
18.06.2025
Applied Crypto Course FS25 - Lab Prizes
This year's edition of the Applied Cryptography course has come to an end!
As part of the course, we run a Capture-the-Flag style competition, were students have to find and exploit cryptographic vulnerabilities in toy servers we create for this purpose.
This year's race was fierce -- here are the three students who solved all of the challenges the fastest! The prize - custom trophies and Applied Crypto mugs!
AC '25 was brought to you by: Felix and Florian, Shannon and Lenka, Yuanming, Kien and Matteo!
30.05.2025
Cryptography in a Changing World: Navigating Geopolitical Uncertainty and Security Risks - Eurocrypt Community Event
Martin Albrecht and Kenny Paterson are the organizers of a community event at this year's Eurocrypt in Madrid.
The event aims to set up a discusson on what we as a community can and should do in light of a dramatically changing domestic and international political landscape. It will take place on Wednesday, May 7, 14:30-16:00 (Room Callao, 3rd floor).
05.05.2025
IACR Distinguished Lecture: Kenny Paterson
The IACR Distinguished Lecture is an annual honour recognizing researchers who have made important contributions to cryptology.
Kenny Paterson has been awarded this year's Distinguished Lecture, and will be presenting at Eurocrypt in Madrid, on Tuesday, May 6, at 14:30. You can follow it in person or online if you are registered to the conference.
04.05.2025
Cryptographic Applications Workshop at Eurocrypt 25
The second edition of the Cryptographic Applications Workshop will be hosted as an associated event at this year's Eurocrypt in Madrid, on Sunday.
CAW focuses on the construction and analysis of cryptography built for practice. Inspired by the Real World Crypto Symposium, it aims to provide a forum for cryptographers in academia and industry to exchange ideas and insights, bridging the gap between research and real-world applications.
CAW is brought to you by Matilda Backendal, Miro Haller, Laura Hetz and Matteo Scarlata.
03.05.2025
Peer2PIR: Private Queries for IPFS at S&P 2025
The InterPlanetary File System (IPFS) is a peer-to-peer network for storing data in a distributed file system, hosting over 190,000 peers spanning 152 countries. Despite its prominence, IPFS has very limited privacy guarantees, leaking every query in the network to the peers. In a recent work, Miti Mazmudar, Shannon Veitch and Rasoul Akhavan Mahdavi try to fix that, integrating state-of-art PIR protocols in the context of distributed systems. "Peer2PIR: Private Queries for IPFS" will be presented this May at S&P in San Francisco.
24.04.2025
AC Group at YRCS
The Applied Crypto Group took part in this spring's edition of the Young Researcher Crypto Seminar, hosted by University of Konstanz.
Our group members presented:
- "Probabilistic Data Structures in Adversarial Settings" - Mia Filic
- "D(e)rive with Care: Lessons Learned from Analyzing Real-World Multi-Input Key Derivation Functions" - Sebastian Clermont (TU Darmstadt) and Matteo Scarlata
- "Two-Server Authenticated Private Information Retrieval with Client-Preprocessing" - Laura Hetz
05.03.2025
Rune visits the Applied Crypto Group
Rune Fielder is in the fifth year of his PhD at TU Darmstadt, under the supervision of Prof. Marc Fischlin.
Rune visited the AC group last week, and presented his work on "BUFFing signatures, post-quantum Signal, and deniable authentication with malicious verifiers”.
We have a record of successful collaborations with Marc and his group, and we enjoyed learning more about Rune's research!
03.03.2025
Applied Crypto at Eurocrypt 2025 - Madrid
Some of our work will appear at Eurocrypt this spring!
- "On the Soundness of Algebraic Attacks against Code-based Assumptions" by Simon-Philipp Merz, Miguel Cueto Noval, Patrick Stählin, Akin Ünal.
- "Key Derivation Functions Without a Grain of Salt" by Matilda Backendal, Sebastian Clermont, Marc Fischlin and Felix Günther.
- "Analysis of the Telegram Key Exchange" by Martin R. Albrecht, Lenka Mareková, Kenny Paterson, Eyal Ronen, Igors Stepanovs.
Looking forward to the talks!
03.02.2025
Applied Crypto Group Retreat
The Applied Crypto Group is back after a refreshing retreat in the Swiss alps! Our annual retreats are an occasion for the group to exercise teamwork, start interesting new research, and enjoy the staggering beauty of our country with hikes and winter sports.
03.02.2025
Welcome back Mia!
Our longest-standing non-permanent member Mia has just came back from 6 months internship at HP Security Labs in Bristol! Now back, Mia is excited to apply new insights and continue growing as a researcher in the realm of Applied Cryptography!
28.01.2025
Applied Crypto at RWC 2025 - Sofia
The Applied Cryptography Group will have a strong presence at this year's RWC, with 5 talks from our group accepted to the programme!
- "Breaking and Fixing Length Leakage in Content-Defined Chunking", by Kien Tuong Truong, Matteo Scarlata, Simon-Philipp Merz, Felix Günther and Kenny Paterson.
- "D(e)rive with Care: Lessons Learned from Analyzing Real-World Multi-Input Key Derivation Functions", by Matilda Backendal, Sebastian Clermont, Marc Fischlin, Felix Günther, Miro Haller and Matteo Scarlata.
- "Mind the Gap! Secure File Sharing, from Theory to Practice", by Matilda Backendal, David Balbás, Nicola Dardanis, Miro Haller and Matteo Scarlata.
- “Kemeleon: Elligator-like Obfuscation for Post-Quantum Cryptography”, by Felix Günther, Michael Rosenberg, Douglas Stebila and Shannon Veitch.
- "Provable Security for End-to-End Encrypted Cloud Storage", by Matilda Backendal, Hannah Davis, Felix Günther, Miro Haller, Kenny Paterson.
We look forward to sharing our research with the wider cryptographic community, and to network with all the awesome people attending RWC! See you in Sofia!
27.01.2025
Applied Crypto at Usenix Security 25
Francesca Falzon will be presenting her work with Tianxin Tang, a former postdoc in our group, titled "Learning from Functionality Outputs: Private Join and Compute (PJC) in the Real World" at this year's Usenix Security Symposium in August 2025.
PJC, a two-party protocol proposed by Google, is used for applications like ad conversion and generalizes their private set intersection sum protocol. It enables two parties with key-value databases to privately compute the inner product of values with intersecting keys. Although the output of this functionality is not usually included in the security model of multi-party computation (MPC), it could pose privacy risks in real-world applications.
Francesca and Tianxin's work examines these risks, focusing on an adversary within the protocol who could exploit four practical attacks to compromise the other party's input privacy. The study underscores the importance of considering functionality output in the MPC security model to mitigate these threats.
20.01.2025
Matilda starts her internship at Apple
Matilda is off to Cupertino this semester. She will be working with Apple's cryptographic team.
We look forward to having her back in May!
19.01.2025