Picture of Sebastian Bitzer

M.Sc. Sebastian Bitzer

Technical University of Munich

Associate Professorship of Coding and Cryptography (Prof. Wachter-Zeh)

Postal address

Postal:
Theresienstr. 90
80333 München

Biography

I received my B.Sc and M.Sc degree in Electrical Engineering  in 2018 and 2021, respectively.
During my studies, I started to collaborate with Prof. Martin Bossert in order to develop efficient hard- and soft-decision decoding algorithms for for algebraic codes.
Under the supervision of Prof. Antonia Wachter-Zeh, I am conducting research on code-based cryptography.

Available Theses

Homomorphic Encryption for Machine Learning

Keywords:
Partial/Somewhat Homomorphic Encryption, Federated Learning

Description

Homomorphic encryption (HE) schemes are increasingly attracting attention in the era of large scale computing. While lattice-based approaches have been well-studied, recently first progress has been made towards establishing code-based alternatives. Preliminary results show that such alterative approaches might enable undiscovered functionalities not present in current lattice-based schemes. In this project, we particularily study novel code-based Partial/Somewhat HE schemes tailored to applications in artificial intelligence and federated learning.

After familiarizing with SotA methods in relevant fields (such as [1]), the student should analyze the requirements for use-cases at hand and explore suitable modifications to current schemes and novel approaches.

Please take note that this Master Thesis is further designed to open up the possibility for a subsequent PhD position in homomorphic encrpytion with Prof. Dr.-Ing. Antonia Wachter-Zeh.

[1] Aguilar-Melchor, Carlos, Victor Dyseryn, and Philippe Gaborit, "Somewhat Homomorphic Encryption based on Random Codes," Cryptology ePrint Archive (2023).

Prerequisites

- Strong foundation in linear algebra
- Channel Coding
- Security in Communications and Storage
- Basic understanding of Machine Learning concepts

Supervisor:

Theses in Progress

Post-Quantum Cyptography based on Codes: the WAVE signature scheme

Keywords:
post-quantum cryptography, code-based, concatenated codes, generalized concatenation

Description

Due to the recent advances in quantum computers, searching for cryptosystems that survive quantum attacks is of great interest. Code-based cryptography is a promising candidate since it is built on the NP-hard problem of decoding a random code [5].

Random-looking codes replace random codes for most cryptosystems to enable a trapdoor. McEliece originally proposed to use binary Goppa codes. Later, MDPC codes were successfully introduced.

More recently, it was suggested that generalized (U|U+V) codes be used, which belong to the class of generalized concatenated codes.
Concatenated codes play an important role in classical channel coding, but further research is required to evaluate which variants also form a promising basis for code-based cryptography.

This topic aims to analyze constructions of generalized concatenated codes proposed for cryptographic applications [2-4], in particular, the WAVE signature scheme [1].

The research internship addresses the following questions:
- how do proposed constructions work?
- which properties do they have?
- is the secret structure well hidden?

 

Main Papers:

[1] Debris-Alazard, T., Sendrier, N., & Tillich, J. P. (2018). Wave: A new code-based signature scheme.

[2] Márquez-Corbella, Irene, and Jean-Pierre Tillich. "Using Reed-Solomon codes in the (U| U+ V) construction and an application to cryptography." 2016 IEEE International Symposium on Information Theory (ISIT). IEEE, 2016.

[3] Puchinger, S., Müelich, S., Ishak, K., & Bossert, M. (2017). Code-based cryptosystems using generalized concatenated codes. In Applications of Computer Algebra: Kalamata, Greece, July 20–23 2015 (pp. 397-423). Springer International Publishing.

[4] Cho, J., No, J. S., Lee, Y., Koo, Z., & Kim, Y. S. (2022). Enhanced pqsigRM: code-based digital signature scheme with short signature and fast verification for post-quantum cryptography. Cryptology ePrint Archive.

Further References:

[5] Weger, V., Gassner, N., & Rosenthal, J. (2022). A Survey on Code-Based Cryptography. arXiv preprint arXiv:2201.07119.



 

Prerequisites

Security in Communications and Storage
Channel Coding

Supervisor:

Publications

2022

  • Bitzer, Sebastian; Bossert, Martin: On Multibasis Information Set Decoding. 2022 IEEE International Symposium on Information Theory (ISIT), 2022 more…
  • Bitzer, Sebastian; Renner, Julian; Wachter-Zeh, Antonia; Weger, Violetta: Generic Decoding in the Cover Metric. arXiv preprint arXiv:2205.12738, 2022 more…
  • Bossert, Martin; Schulz, Rebekka; Bitzer, Sebastian: On Hard and Soft Decision Decoding of BCH Codes. IEEE Transactions on Information Theory 68 (11), 2022, 7107--7124 more…

2019

  • Müelich, Sven; Bitzer, Sebastian; Sudarshan, Chirag; Weis, Christian; Wehn, Norbert; Bossert, Martin; Fischer, Robert FH: Channel Models for Physical Unclonable Functions based on DRAM Retention Measurements. 2019 XVI International Symposium" Problems of Redundancy in Information and Control Systems"(REDUNDANCY), 2019 more…