Foundations of Cryptography
Foundations of Cryptography
Akin Ünal won the Early Career Best Paper Award at EUROCRYPT 2023 with his paper "Worst-Case Subexponential Attacks on PRGs of Constant Degree or Constant Locality". Congratulations Akin!
Cryptography is a crucial tool for securing information systems. Cryptographic building blocks ensure the secrecy and integrity of information, and help to protect the privacy of users. Still, most actually deployed cryptographic schemes are not known to have any rigorously proven security guarantees. This has led to a number of far-reaching security issues in widely deployed software systems.
Our goal is to provide practical cryptographic building blocks that come with rigorously proven security guarantees. These building blocks should be efficient enough for the use in large-scale modern information systems, and their security should be defined and formally analyzed in a mathematically rigorous manner.
We are interested in the foundations of theoretical cryptography, and in general ways to derive constructions and security guarantees in a modular fashion. One research focus in our group concerns new cryptographic building blocks such as indistinguishability obfuscation, functional encryption, and fully homomorphic encryption. We are particularly interested in the design and analysis of cryptographic schemes in the public-key setting. This covers common tools like public-key encryption and digital signatures, specifically in realistic modern scenarios (such as settings with adaptive adversaries, and a huge number of users).
This information concerns the “Digital Signatures” lecture in the Spring 2024 semester at ETH. The content for this course will be provided through Moodle.
This information concerns the “Information Security” lecture in the Spring 2024 semester at ETH. The content for this course will be provided through Moodle.
Information about the course will be communicate to the subscribed participants via email.
Starting with the autumn semester 2025, the Discrete Math lecture will be held by Prof. Hofheinz. If you are interested in becoming a student/teaching assistant, please contact Roman Langrehr (roman.langrehr@inf.ethz.ch).
A t-out-of-N threshold signature
distributes a secret key among N parties, such that any group of at least t parties can jointly produce a valid siganture. Importantly, even if up to t-1 parties are corrupted, an adversary still cannot forge signatures. Threshold signatures have practical applications, such as blockchain systems. Recently, NIST has launched a standardization effort [1] for multi-party threshold protocols.
While there are efficient constructions with strong security guarantees in the classical (pre-quantum) settings, research on post-quantum (in particular, lattice-based) threshold signatures remains limited (see e.g. [2]), and many existing constructions provide only weak security guarantees.
The aim of this project is to enhance the security guarantees of existing lattice-based threshold signatures. In particular, the project will focus on applying existing technique for distributed key generation and for adaptive security to existing lattice-based constructions to enhance their security guarantees.
A student interested in this thesis should have a background in crytography (Information Security course, Digital Signature course, etc.) and basic knowledge of mathematics
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