Multi-User Security in Post-Quantum Cryptography
Event details
| Date | 12.06.2025 |
| Hour | 16:00 › 18:00 |
| Speaker | Lewis Glabush |
| Location | |
| Category | Conferences - Seminars |
EDIC candidacy exam
Exam president: Prof. Thomas Vidick
Thesis advisor: Prof. Serge Vaudenay
Co-examiner: Prof. Alessandro Chiesa
Abstract
Multi-user security is an important topic in post-quantum public key cryptographic, which has received limited attention in the literature. Multi-user security captures how security degrades as protocols are used at scale. Trivial bounds have existed in the literature since 2000, but are insufficient to maintain security tightness at scale. For concrete schemes, better-than-trivial bounds are suggested by existing heuristics. This thesis will consider the impact of cryptography at scale for lattice-based schemes. We will consider known techniques to improve multi-user security: user domain seperation and salting. Furthermore, we will describe the optimal key-refresh rates, and the expected failure rate, for lattice based schemes used at scale.
Selected papers
1: Tightness Subtleties for Multi-user PKE Notions. Eprint version: https://eprint.iacr.org/2022/855. IMA version: https://link.springer.com/chapter/10.1007/978-3-030-92641-0_5. (The versions are the same).
2: Public-Key Encryption in a Multi-user Setting: Security Proofs and Improvements https://www.iacr.org/archive/eurocrypt2000/1807/18070262-new.pdf.
3: Faster Lattice-Based KEMs via a Generic Fujisaki-Okamoto Transform Using Prefix Hashing. https://eprint.iacr.org/2021/1351.pdf. ACM CCS version: https://dl.acm.org/doi/10.1145/3460120.3484819. (The versions are the same).
Exam president: Prof. Thomas Vidick
Thesis advisor: Prof. Serge Vaudenay
Co-examiner: Prof. Alessandro Chiesa
Abstract
Multi-user security is an important topic in post-quantum public key cryptographic, which has received limited attention in the literature. Multi-user security captures how security degrades as protocols are used at scale. Trivial bounds have existed in the literature since 2000, but are insufficient to maintain security tightness at scale. For concrete schemes, better-than-trivial bounds are suggested by existing heuristics. This thesis will consider the impact of cryptography at scale for lattice-based schemes. We will consider known techniques to improve multi-user security: user domain seperation and salting. Furthermore, we will describe the optimal key-refresh rates, and the expected failure rate, for lattice based schemes used at scale.
Selected papers
1: Tightness Subtleties for Multi-user PKE Notions. Eprint version: https://eprint.iacr.org/2022/855. IMA version: https://link.springer.com/chapter/10.1007/978-3-030-92641-0_5. (The versions are the same).
2: Public-Key Encryption in a Multi-user Setting: Security Proofs and Improvements https://www.iacr.org/archive/eurocrypt2000/1807/18070262-new.pdf.
3: Faster Lattice-Based KEMs via a Generic Fujisaki-Okamoto Transform Using Prefix Hashing. https://eprint.iacr.org/2021/1351.pdf. ACM CCS version: https://dl.acm.org/doi/10.1145/3460120.3484819. (The versions are the same).
Practical information
- General public
- Free
Contact
- edic@epfl.ch