Master's Theses
Available Projects
Students interested in a thesis with the group are kindly requested to send their transcript of records, along with a CV highlighting any relevant experience in cryptography, and either a preferred topic from the proposals below or a description of their interests within cryptography, to the contact noted under Student Projects.
Last updated: 02.10.2026
Ongoing Projects
(We recommend students currently doing a project in our group to use this Download LaTeX template for writing their thesis.)
(Supervisor: Prof. Kenny Paterson, Joint Supervisor: Yuanming Song)
This project investigates how modern compression algorithms can leak sensitive information through compression side channels, where changes in compressed output size reveal properties of the underlying data even when it is encrypted. While previous attacks have mainly targeted the older DEFLATE algorithm, this work focuses on newer and increasingly popular schemes such as brotli and Zstandard, and potentially others like LZ4, Snappy, LZMA, and bzip2. A key goal is to understand how vulnerable these algorithms are to side-channel attacks and how an attacker might amplify small differences in input into large, observable changes in compressed length.
The project will adapt known exploitation techniques from DEFLATE, such as telescoping and chaining, to brotli and Zstandard, studying how well they transfer and why they may behave differently. It will also develop new, algorithm-specific techniques that exploit unique design features, complex encoding schemes (such as FSE in Zstandard), static dictionaries, and heuristic optimizations in reference implementations. Because many compression algorithms lack formal specifications, the work will rely heavily on analyzing their source code, implementing attack strategies, and empirically evaluating their effectiveness in realistic scenarios.
(Supervisor: Prof. Kenny Paterson, Joint Supervisors: Dr. David Balbás, Mara Mihali)
Proof systems are a fundamental tool in modern cryptography, with applications in authentication, verifiable computation, digital signatures, blockchain protocols, and digital identity systems. Designing and deploying practical proof systems, however, involves significant challenges. A central issue is the tension between efficiency and security. While highly secure constructions are known, they are often too inefficient for practical use. Consequently, most deployed proof systems rely on the Fiat-Shamir heuristic, which transforms interactive protocols into non-interactive ones by modeling a cryptographic hash function as a random oracle. Recently, Khovratovich, Rothblum, and Soukhanov presented the first attack targeting the Fiat-Shamir transform itself for a broad class of protocols, although its impact in practice is, for now, very limited.
The goal of this project is to study this attack on Fiat-Shamir, implement it, and explore extensions and variations of the attacks.
This Master’s thesis proposal aims to develop a quantum-resistant replacement for Tor’s ntor-v3 handshake protocol. ntor-v3 establishes shared symmetric keys between Tor clients and relay nodes while authenticating relays and preserving client anonymity, but its Diffie–Hellman basis would be vulnerable to sufficiently capable quantum computers. Existing post-quantum replacement proposals can increase message sizes, computation time, and handshake round trips—issues that may become more significant under Tor’s proposed Walking Onions design.
The project will formalize the security requirements for a successor, including secrecy/forward secrecy, relay authentication, and client anonymity, and assess current proposals against them. It will then design and formally prove secure a more efficient post-quantum protocol, potentially exploiting Tor’s handshake structure rather than applying generic KEM substitutions. The resulting design will be evaluated against ntor-v3 and existing alternatives for bandwidth, round trips, runtime, and computation; if time permits, it will be prototyped in the Arti Tor implementation.
This Master’s thesis examines cryptographic primitives that combine confidentiality with sender authentication: signcryption, split Key Encapsulation Mechanisms (split KEMs), and Authenticated KEMs (AKEMs). Although these constructions serve similar purposes and may have compatible interfaces, they use different key-generation models and are defined through differing security notions. The thesis will systematically translate and compare these notions, including confidentiality, authenticity, and deniability, establishing where one property implies, excludes, or can exist independently of another.
The project will also investigate how these primitives can support the initial handshake of a secure messaging protocol, where two parties need to establish a shared session key with mutual authentication. It will analyze a straightforward handshake construction based on split KEMs, AKEMs, and/or signcryption, identifying the precise underlying guarantees needed to match state-of-the-art confidentiality, authentication, and deniability properties. The final result will provide a compact comparison of the relevant security definitions and practical guidance on the trade-offs involved in choosing primitives for messaging handshakes.
Completed Projects
2026
Fabio Giovanazzi: Messaging Without Borders: Improving Secure Mesh Networks. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Lenka Mareková.
Timon Meyer: Crypto in the Wild: SimpleX. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Rune Fiedler.
Ștefan Malanik: On Constant Communication in Dynamic MPC. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Martin Hirt.
Andris Suter-Dörig. Breaking SEPPmail: A Case Study of Email Encryption in the Wild [Download pdf (PDF, 1.7 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Matteo Scarlata.
2025
Andrea Raguso. Analyzing Private Set Union and Data Join Functionalities. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Francesca Falzon.
Marc Himmelberger. Implementing and Evaluating Quantum-Safe Fully Encrypted Protocols [Download pdf (PDF, 1.7 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Shannon Veitch, Dr. Felix Günther (IBM Research, Zurich).
Emanuel Opel. Shamir Secret (Over)sharing, in the Wild. Supervisor: Prof. Kenny Paterson, Co-supervisor: Kien Tuong Truong.
Giovanni Torrisi. Common Pitfalls in End-to-End Encrypted Password Managers. Supervisor: Prof. Kenny Paterson, Co-supervisors: Matilda Backendal, Matteo Scarlata.
Damiano Mombelli. General-Purpose Zero-Knowledge Proofs for Verifiable Credentials [Download pdf (PDF, 898 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Martin Burkhart (Armasuisse).
Moritz Teichner. Bandwidth-Efficient Multi-Server Oblivious Message Retrieval. Supervisor: Prof. Kenny Paterson, Co-supervisor: Laura Hetz.
2024
Nicola Dardanis. Bridging the Gap: Design and Implementation of Secure Shared Folders [Download pdf (PDF, 1.1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Matilda Backendal, Matteo Scarlata.
Antonino Orofino. An Investigation of VPN Fingerprinting. Supervisor: Prof. Kenny Paterson, Co-supervisors: Shannon Veitch, Dr. Lenka Mareková.
Valentina Iliescu. Multi-Device Password Hardening [Download pdf (PDF, 488 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Matteo Scarlata, Matilda Backendal.
Cedric Gebistorf. Breaking Cryptography in the Wild: PrivateStorage [Download pdf (PDF, 1.5 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Kien Tuong Truong.
Yuanming Song. Refined Techniques for Compression Side-Channel Attacks [Download pdf (PDF, 910 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Lenka Mareková.
Jonas Hofmann. Breaking Cryptography in the Wild: Cloud Storage. Supervisor: Prof. Kenny Paterson, Co-supervisor: Kien Tuong Truong.
Noah Schmid. Breaking Cryptography in the Wild: Rocket.Chat [Download pdf (PDF, 1.1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Jan Gilcher.
Aurel Feer. Privacy Preserving String Search using Homomorphic Encryption [Download pdf (PDF, 1.1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Zichen Gui.
Léa Micheloud. Securing Cloud Storage with OpenPGP: An Analysis of Proton Drive [Download pdf (PDF, 2.1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Matilda Backendal, Daniel Huigens (Proton AG, Zurich).
2023
Daniel Pöllmann. Differential Obliviousness and its Limitations. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Tianxin Tang.
Andreas Tsouloupas. Breaking Cryptography in the Wild: Double-Ratchet Mutations [Download pdf (PDF, 966 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Matteo Scarlata, Kien Tuong Truong.
Thore Göbel. Security Analysis of Proton Key Transparency [Download pdf (PDF, 1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Daniel Huigens (Proton AG, Zurich), Felix Linker.
Sina Schaeffler. Algorithms for Quaternion Algebras in SQIsign [Download pdf (PDF, 664 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Luca De Feo (IBM Research, Zurich).
Lucas Dodgson. Post-Quantum building blocks for secure computation - the Legendre OPRF [Download pdf (PDF, 862 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Julia Hesse, Sebastian Faller (IBM Research, Zurich).
Mirco Stäuble. Mitigating Impersonation Attacks on Single Sign-On with Secure Hardware [Download pdf (PDF, 2.1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Julia Hesse, Sebastian Faller (IBM Research, Zurich).
Younis Khalil. Implementing a Forward-Secure Cloud Storage System [Download pdf (PDF, 5.6 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Felix Günther, Matilda Backendal.
Andrei Herasimau. Formal Verification of the "Crypto Refresh" Update to the OpenPGP Standard [Download pdf (PDF, 695 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Daniel Huigens (Proton Mail).
Benjamin Fischer. Privacy-Preserving Federated Learning for Cyber Threat Intelligence Sharing [Download pdf (PDF, 3.3 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Juan R. Troncoso-Pastoriza (Tune Insight SA).
Pascal Schärli. Security Assessment of the Sharekey Collaboration App [Download pdf (PDF, 2.9 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Bernhard Tellenbach (Armasuisse).
Lena Csomor. Bridging the Gap between Privacy Incidents and PETs [Download pdf (PDF, 1.3 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Anwar Hithnawi, Alexander Viand, Shannon Veitch.
2022
Ran Liao. Linear-Time Zero-Knowledge Arguments in Practice. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Jonathan Bootle (IBM Research, Zurich).
Christian Knabenhans. Practical Integrity Protection for Private Computations [Download pdf (PDF, 873 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Anwar Hithnawi, Alexander Viand.
Ella Kummer. Counting filters in adversarial settings [Download pdf (PDF, 943 KB)]. Supervisor. Prof. Kenny Paterson, Co-supervisors: Dr. Anupama Unnikrishnan, Mia Filić.
Massimiliano Taverna. Breaking Cryptography in the Wild: Web3 [Download pdf (PDF, 1.4 MB)]. Supervisor: Prof. Kenny Paterson.
Giacomo Fenzi. Klondike: Finding Gold in SIKE [Download pdf (PDF, 7.6 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Fernando Virdia.
Kien Tuong Truong. Breaking Cryptography in the Wild: Threema [Download pdf (PDF, 824 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Matteo Scarlata.
Jonas Meier. Diophantine Satisfiability Arguments for Private Blockchains [Download pdf (PDF, 2.1 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Patrick Towa.
Marc Ilunga. Analysis of the EDHOC Lightweight Authenticated Key Exchange Protocol [Download pdf (PDF, 1.2 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Felix Günther.
Robertas Maleckas. Cryptography in the Wild: Analyzing Jitsi Meet [Download pdf (PDF, 996 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Prof. Martin Albrecht.
Miro Haller. Cloud Storage Systems: From Bad Practice to Practical Attacks [pdf]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Matilda Backendal.
Lorenzo Laneve. Quantum Random Walks [pdf]. Joint supervisor: Prof. Kenny Paterson.
Florian Moser. Swiss Internet Voting [pdf]. Supervisor: Prof. Kenny Paterson.
2021
Moritz Winger. Automated Hybrid Parameter Selection & Circuit Analysis for FHE [pdf]. Joint supervisor: Prof. Kenny Paterson, Co-supervisor: Alexander Viand.
Tijana Klimovic. Modular Design of the Messaging Layer Security (MLS) Protocol [Download pdf (PDF, 1.3 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Igors Stepanovs.
Radwa Abdelbar. Post-Quantum KEM-based TLS with Pre-Shared Keys [Download pdf (PDF, 972 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Felix Günther, Dr. Patrick Towa.
Raphael Eikenberg. Breaking Bridgefy, Again [pdf]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Prof. Martin Albrecht.
Andreas Pfefferle. Security Analysis of the Swiss Post’s E-Voting Implementation. Supervisor: Prof. Kenny Paterson.
Mihael Liskij. Survey of TLS 1.3 0-RTT Usage [Download pdf (PDF, 803 KB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Felix Günther.
Nicolas Klose. Characterizing Notions for Secure Cryptographic Channels [Download pdf (PDF, 1.4 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Felix Günther.
Alexandre Poirrier. Continuous Authentication in Secure Messaging [pdf]. Supervisor: Prof. Kenny Paterson, Co-supervisors: Dr. Benjamin Dowling, Dr. Felix Günther.
Luca Di Bartolomeo. ArmWrestling: efficient binary rewriting for ARM [Download pdf (PDF, 661 KB)]. Joint Supervisor: Prof. Kenny Paterson.
2020
Matteo Scarlata. Post-Compromise Security and TLS 1.3 Session Resumption [Download pdf (PDF, 1.5 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Benjamin Dowling.
Anselme Goetschmann. Design and Analysis of Graph Encryption Schemes [Download pdf (PDF, 2.9 MB)]. Supervisor: Prof. Kenny Paterson, Co-supervisor: Dr. Sikhar Patranabis.
Lara Bruseghini. Analysis of the OpenPGP Specifications and Usage. Joint Supervisor: Prof. Kenny Paterson.
Semira Einsele. Average Case Error Estimates of the Strong Lucas Probable Prime Test [Download pdf (PDF, 893 KB)]. Joint Supervisor: Prof. Kenny Paterson.
Jan Gilcher. Constant-Time Implementation of NTS-KEM [Download pdf (PDF, 3.2 MB)]. Supervisor: Prof. Kenny Paterson.