Julian Wilhelm Renner

I’m a researcher in the group Coding for Communications and Data Storage at the Technical University of Munich (TUM), where I’m pursuing the Dr.-Ing. degree in the area of post-quantum cryptography.

Besides cryptography, I have published articles in the fields of coding theory and fiber-optic communication. Further, I have submitted a patent application for radar sensing.

I'm interested in

Cryptography, Communication and Sensing

Enabling secure, fast and reliable communication and radar by developing new methods in the fields of cryptography, channel coding, information theory and digital signal processing.

Capital Markets

The theory of financial decision making under uncertainty and the implementation of portfolios based on scientifically sound and well-studied multi-factor models.

IT Services

Home servers based on virtualization management platforms that provide functionalities like virtual private network connections, DNS resolution, cloud storage, website hosting, etc.



10/2017 - Current
Technical University of Munich

Doctoral researcher

Scientist in the group Coding for Communications and Data Storage

Supervisor: Prof. Dr.-Ing. Antonia Wachter-Zeh

Research area: Post-quantum cryptography

03/2019 - 05/2019
University of Rennes 1
02/2017 - 10/2017
Eindhoven University of Technology

Doctoral Researcher

Scientist in the group Signal Processing Systems

Supervisor: Prof. Dr. Frans Willems

Research area: Embedding digital communication in car radars

03/2015 - 08/2015
Rohde & Schwarz

Part-time Engineer

Department: Development of Baseband-HW and Signalgenerators for Wireless Applications

Tasks: development and implementation of automatization and test routines in C++

04/2014 - 07/2014
Technical University of Munich

Student Teaching Assistant

Lecture: Control Systems 1 (Prof. Buss’s Chair of Automatic Control Engineering)

Offered as a result of an excellent performance in the examination

08/2013 - 10/2013
Rosenberger High-Frequency Technology


Department: Research and Development


  • Measurement of cable-connector combinations with spectrum analyzers

  • Evaluation of the in-house training kit

04/2013 - 07/2013
Technical University of Munich

Student Teaching Assistant

Laboratory: Audio and Image Processing (Prof. Rigoll’s Institute for Human-Machine Communication)

Offered as a result of an excellent performance in the lecture ”Signals”


06/2014 - 12/2016
Technical University of Munich

M.Sc. Electrical and Computer Engineering

Focus on Communication Systems, Information Theory and Digital Signal Processing

Master’s thesis on ”Multidimensional Probabilistic Shaping for the Nonlinear Fiber Channel” at the Institute for Communications Engineering in collaboration with Prof. Forchhammer, Technical University of Denmark.

Grade average: 1.0 (passed with high distinction, US-equivalent: A+)

08/2015 - 01/2016
Technical University of Denmark

ERASMUS program in the fall term

Focus on Machine Learning and Pattern Recognition, Optimization and Data Fitting, the Programming Language C++

Grade average: 12 on 7-grades-scale (TUM-equivalent: 1.0, US-equivalent: A+)

05/2011 - 06/2014
Technical University of Munich

B.Sc. Electrical and Computer Engineering

Focus on Communication Technology and Digital Signal Processing

Bachelor’s thesis on ”Quantization of Log-Likelihood-Ratios in Multiple-Input Multiple-Output Systems” at Prof. Utschick’s Chair of Signal Processing Methods

Grade average: 1.5 (passed with distinction, US-equivalent: A)


Sponsorship by Rheinmetall


Scholarship for young outstanding talents at Technical University of Munich

Sponsorship by German Academic Exchange Service (DAAD)

FIT weltweit

Performance-related scholarship for international research stays

Sponsorship by MAN Truck & Bus Company


Scholarship for young outstanding talents at Technical University of Munich

Sponsorship by Wipro Technologies


Scholarship for young outstanding talents at Technical University of Munich

Coding Skills












Post-Quantum Cryptography

Assuming a cyber attack initiated from a sufficiently powerful quantum computer, several classical public-key algorithms become insecure. These algorithms are based on factoring large integers and the discrete logarithm problem which are easy-to-solve in a post-quantum world. Thus, the National Institute of Standards and Technology (NIST) launched the Post-Quantum Cryptography Standardization. My research focuses on assessing the hardness of mathematical problems that can serve as the core to such cryptosystems, analysing the security of existing schemes and constructing new efficient public-key algorithms in the context of post-quantum cryptography.

Fiber-Optic Communication

In today’s communication systems, virtually all IP-based traffic is transmitted over non-linear optical fiber channels. Scenarios of future demands indicate a requirement of higher and higher data-rates, making the improvement of optical communication systems especially important. A key technology for achieving a higher throughput is coherent fiber optic telecommunication. This development allows for the use of not only the power but also the phase of the signal to transmit information, i.e., higher order modulation techniques, like quadrature amplitude modulation, can be applied. However, uncompensated Kerr nonlinearity limits the effective signal-to-noise ratio and thus, the throughput cannot be increased by increasing the modulation alphabet size. Therefore, I'm interested in developing new methods that increase the spectral efficiency of nonlinear fiber systems.

MIMO Communication

Modern wireless communication systems have to provide higher and higher data rates. Since conventional methods like using more bandwidth or higher order modulation types are limited, Multiple-Input Multiple-Output (MIMO) technology constitutes a breakthrough. The technology offers significant increases in data throughput without additional bandwidth or increased transmit power. This is possible by the fact, that the channel capacity of a MIMO channel is larger than the channel capacity of a Single-Input Single-Output channel. In order to have a rate close to channel capacity, the signals are encoded before the transmission and decoded at the receiver side. The used decoding algorithms require statements about the certainty of the received signals. Log-Likelihood-Ratios deliver such information, but since they have a continuous range, their standard representation as floating point numbers requires a disproportional large amount of bandwidth. Thus,  I investigate new quantization strategies that improve the bandwidth efficiency but still allow a good decoding performance.


I have collaborated with more than 20 engineers, mathematicians and computer scientists from academia, industry and defense organizations. These collaborations led to peer-reviewed journal publications and conference papers in the areas of post-quantum cryptography, coding theory, fiber-optic communication and radar. The author orderings of my publications are not consistent. Depending on the co-authors, it is sometimes alphabetically. All my papers can be found on ArXiv and on Google Scholar.

Journal Publications

[Preprint] LIGA: A Cryptosystem Based on the Hardness of Rank-Metric List and Interleaved Decoding

Renner, J.; Puchinger, S. and Wachter-Zeh, A.; Submitted to Designs, Codes, and Cryptography (DCC)

[Preprint] Decoding High-Order Interleaved Rank-Metric Codes

Puchinger, S.; Renner, J. and Wachter-Zeh, A.; Submitted to IEEE Transactions on Information Theory (TIT)

Low-Rank Parity-Check Codes over Galois Rings

Renner, J., Neri, A. and Puchinger, S.; Accepted at Designs, Codes, and Cryptography (DCC), 2020

Cryptanalysis of a System Based on Twisted Reed–Solomon Codes

Lavauzelle, J. and Renner, J.; Designs, Codes, and Cryptography (DCC), 2020

Experimental Comparison of Probabilistic Shaping Methods for Unrepeated Fiber Transmission

Renner, J.; Fehenberger, T.; Yankov, P.; Da Ros, F.; Forchhammer, S.; Böcherer, G and Hanik, N.; IEEE/OSA Journal of Lightwave Technology (JLT), 2017


Radar Sensing

Laghezza, F.; Renner, J.; Willems, F.; Serbetli, S.; Alvarado, A.; Patent application 16/402932, 2019

Peer-reviewed Conference Papers

Randomized Decoding of Gabidulin Codes Beyond the Unique Decoding Radius

Renner, J.; Jerkovits, T.; Bartz, H.; Puchinger, S.; Loidreau, P.; Wachter-Zeh, A.; The Eleventh International Conference on Post-Quantum Cryptography (PQCrytpo), 2020

Generic Decoding in the Sum-Rank Metric

Puchinger, S.; Renner, J.; Rosenkilde, J.; IEEE International Symposium on Information Theory (ISIT), 2020

Low-Rank Parity-Check Codes over the Ring of Integers Modulo a Prime Power

Renner, J.; Puchinger, S.; Wachter-Zeh, A.; Hollanti, C.; Freij-Holanti, R.; IEEE International Symposium on Information Theory (ISIT), 2020

A Power Side-Channel Attack on the CCA2-Secure HQC KEM

Schamberger, T.; Renner, J.; Sigl, G.; Wachter-Zeh A.; 19th Smart Card Research and Advanced Application Conference (CARDIS2020), 2020

On Software Implementation of Gabidulin Decoders

Kunz, J.; Renner, J.; Maringer, G.; Schamberger, T.; Wachter-Zeh, A.; Seventeenth International Workshop on Algebraic and Combinatorial Coding Theory (ACCT), 2020

Efficient Decoding of Interleaved Low-Rank Parity-Check Codes

Renner, J., Jerkovits, T., Bartz, H.; XVI International Symposium Problems of Redundancy in Information and Control Systems, 2019

Interleaving Loidreau’s Rank-Metric Cryptosystem

Renner, J., Puchinger, S., Wachter-Zeh, A.; XVI International Symposium Problems of Redundancy in Information and Control Systems, 2019

Twisted Gabidulin Codes in the GPT Cryptosystem

Puchinger, S.; Renner, J.; Wachter-Zeh, A.; Sixteenth International Workshop on Algebraic and Combinatorial Coding Theory (ACCT), 2018

Repairing the Faure-Loidreau Public-Key Cryptosystem

Wachter-Zeh, A.; Puchinger, S.; Renner, J.; IEEE International Symposium on Information Theory (ISIT), 2018

Impressum & Privacy Policy


Julian Renner
Technical University of Munich
Institute for Communications Engineering
Theresienstrasse 90
80333 München

Telephone: +49 89 289 29053
Email: julian.renner@tum.de

Privacy Policy

Personal data (usually referred to just as "data" below) will only be processed by us to the extent necessary and for the purpose of providing a functional and user-friendly website, including its contents, and the services offered there.

Per Art. 4 No. 1 of Regulation (EU) 2016/679, i.e. the General Data Protection Regulation (hereinafter referred to as the "GDPR"), "processing" refers to any operation or set of operations such as collection, recording, organization, structuring, storage, adaptation, alteration, retrieval, consultation, use, disclosure by transmission, dissemination, or otherwise making available, alignment, or combination, restriction, erasure, or destruction performed on personal data, whether by automated means or not.

The following privacy policy is intended to inform you in particular about the type, scope, purpose, duration, and legal basis for the processing of such data either under our own control or in conjunction with others. We also inform you below about the third-party components we use to optimize our website and improve the user experience which may result in said third parties also processing data they collect and control.

Our privacy policy is structured as follows:

I. Information about us as controllers of your data
II. The rights of users and data subjects
III. Information about the data processing

I. Information about us as controllers of your data

The party responsible for this website (the "controller") for purposes of data protection law is:

Julian Renner
Technical University of Munich
Institute for Communications Engineering
Theresienstrasse 90
80333 München

Telephone: +49 89 289 29053
Email: julian.renner@tum.de

II. The rights of users and data subjects

With regard to the data processing to be described in more detail below, users and data subjects have the right

  • to confirmation of whether data concerning them is being processed, information about the data being processed, further information about the nature of the data processing, and copies of the data (cf. also Art. 15 GDPR);
  • to correct or complete incorrect or incomplete data (cf. also Art. 16 GDPR);
  • to the immediate deletion of data concerning them (cf. also Art. 17 DSGVO), or, alternatively, if further processing is necessary as stipulated in Art. 17 Para. 3 GDPR, to restrict said processing per Art. 18 GDPR;
  • to receive copies of the data concerning them and/or provided by them and to have the same transmitted to other providers/controllers (cf. also Art. 20 GDPR);
  • to file complaints with the supervisory authority if they believe that data concerning them is being processed by the controller in breach of data protection provisions (see also Art. 77 GDPR).

In addition, the controller is obliged to inform all recipients to whom it discloses data of any such corrections, deletions, or restrictions placed on processing the same per Art. 16, 17 Para. 1, 18 GDPR. However, this obligation does not apply if such notification is impossible or involves a disproportionate effort. Nevertheless, users have a right to information about these recipients.

Likewise, under Art. 21 GDPR, users and data subjects have the right to object to the controller's future processing of their data pursuant to Art. 6 Para. 1 lit. f) GDPR. In particular, an objection to data processing for the purpose of direct advertising is permissible.

III. Information about the data processing

Your data processed when using our website will be deleted or blocked as soon as the purpose for its storage ceases to apply, provided the deletion of the same is not in breach of any statutory storage obligations or unless otherwise stipulated below.

Server data

For technical reasons, the following data sent by your internet browser to us or to our server provider will be collected, especially to ensure a secure and stable website: These server log files record the type and version of your browser, operating system, the website from which you came (referrer URL), the webpages on our site visited, the date and time of your visit, as well as the IP address from which you visited our site.

The data thus collected will be temporarily stored, but not in association with any other of your data.

The basis for this storage is Art. 6 Para. 1 lit. f) GDPR. Our legitimate interest lies in the improvement, stability, functionality, and security of our website.

The data will be deleted within no more than seven days, unless continued storage is required for evidentiary purposes. In which case, all or part of the data will be excluded from deletion until the investigation of the relevant incident is finally resolved.


If you contact us via email or the contact form, the data you provide will be used for the purpose of processing your request. We must have this data in order to process and answer your inquiry; otherwise we will not be able to answer it in full or at all.

The legal basis for this data processing is Art. 6 Para. 1 lit. b) GDPR.

Your data will be deleted once we have fully answered your inquiry and there is no further legal obligation to store your data, such as if an order or contract resulted therefrom.

Social media links via graphics

We also integrate the following social media sites into our website. The integration takes place via a linked graphic of the respective site. The use of these graphics stored on our own servers prevents the automatic connection to the servers of these networks for their display. Only by clicking on the corresponding graphic will you be forwarded to the service of the respective social network.

Once you click, that network may record information about you and your visit to our site. It cannot be ruled out that such data will be processed in the United States.

Initially, this data includes such things as your IP address, the date and time of your visit, and the page visited. If you are logged into your user account on that network, however, the network operator might assign the information collected about your visit to our site to your personal account. If you interact by clicking Like, Share, etc., this information can be stored your personal user account and possibly posted on the respective network. To prevent this, you need to log out of your social media account before clicking on the graphic. The various social media networks also offer settings that you can configure accordingly.

The following social networks are integrated into our site by linked graphics:

Google Scholar

Google Ireland Limited, Gordon House, Barrow Street, Dublin 4, Irland, a subsidiary of Google LLC, 1600 Amphitheatre Parkway, Mountain View, CA 94043 USA

Privacy Policy: https://policies.google.com/privacy

Jetpack - WordPress Stats

Our website uses Jetpack with the WordPress Stats extension. This is a web analysis service provided by Automattic Inc, 132 Hawthorne Street, San Francisco, CA 94107, USA, hereinafter referred to as "Automattic".

The Jetpack: WordPress Stats services is used to analyze how our website is used. The legal basis is Art. 6 Para. 1 lit. f) GDPR. Our legitimate interest lies in the analysis, optimization, and economic operation of our site.

Jetpack: WordPress Stats stores cookies on your device via your browser in order to analyze how you use our site.

Data such as your IP address, the pages you visit, the website from which you came (referrer URL), the duration of your visit, and the frequency of your visits will be processed. The data collected will be stored on an Automattic server in the USA. However, your IP address will be made anonymous immediately after processing and before it is stored.

If you do not agree to this processing, you have the option of preventing the installation of cookies by making the appropriate settings in your browser. Further details can be found in the section about cookies above.

Model Data Protection Statement for Anwaltskanzlei Weiß & Partner

WordPress Appliance - Powered by TurnKey Linux