Felix Günther





I am a postdoctoral researcher in the Applied Cryptography Group at ETH Zurich, working with Kenny Paterson, supported by a research fellowship of the German Research Foundation (DFG).

Prior to that, I was a postdoc in the Security and Cryptography Group at UC San Diego, working with Mihir Bellare, and in the Cryptography and Complexity Theory (Cryptoplexity) Group at Technische Universität Darmstadt, led by Marc Fischlin. I obtained my Ph.D. in Computer Science from TU Darmstadt in February 2018 under the supervision of Marc Fischlin, and, earlier, M.Sc. degrees in Computer Science and IT Security from TU Darmstadt. I am a member of the IACR.

Research Interests

I am interested in applied cryptography enabling computer security, and provable cryptographic security more specifically. My work aims to narrow the gap between the theoretical understanding and practical security of real-world cryptographic systems. To this end, I especially investigate the provable security of (Internet) cryptographic protocols for key exchange and secure channels, for example the prominent Transport Layer Security (TLS) protocol. In doing so, my work broadly encompasses theoretical modeling of security properties and assumptions, provable-security analyses of real-world protocols, as well as guidance on practical protocol design.


2020-10-08My article Modeling advanced security aspects of key exchange and secure channel protocols [3] summarizing my Ph.D. thesis was published in the journal it - Information Technology as part of its Distinguished Dissertations series.
2020-09-18Our paper Towards Post-Quantum Security for Signal's X3DH Handshake [8] (with Jacqueline Brendel, Marc Fischlin, Christian Janson, and Douglas Stebila) was accepted to SAC 2020. It is available on ePrint.
2020-08-26Our paper A Cryptographic Analysis of the TLS 1.3 Handshake Protocol [4] (with Benjamin Dowling, Marc Fischlin, and Douglas Stebila) was accepted to the Journal of Cryptology for a special issue on TLS 1.3. It is available on ePrint.
2020-08-26Our paper Tighter Proofs for the SIGMA and TLS 1.3 Key Exchange Protocols [1] (with Hannah Davis) is now available on ePrint.
2020-06-15Our paper Robust Channels: Handling Unreliable Networks in the Record Layers of QUIC and DTLS 1.3 [2] (with Marc Fischlin and Christian Janson) is now available on ePrint. Our results informed the IETF QUIC and TLS working groups, leading to forgery limits to the upcoming standards for QUIC and DTLS 1.3.

Academic Career and Education

since 2019Postdoctoral researcher in the Applied Cryptography Group at ETH Zurich

Working with: Prof. Kenneth G. Paterson

2018–2019Postdoctoral researcher in the Security and Cryptography Group at UC San Diego

Working with: Prof. Mihir Bellare

2018Postdoctoral researcher in the Cryptoplexity Group at TU Darmstadt

Working with: Prof. Marc Fischlin

2013–2018Ph.D. in Computer Science, TU Darmstadt

Thesis: Modeling Advanced Security Aspects of Key Exchange and Secure Channel Protocols [32]
Advisor: Prof. Marc Fischlin

2010–2013M.Sc. in Computer Science, TU Darmstadt
M.Sc. in IT Security, TU Darmstadt
2007–2010B.Sc. in Computer Science, TU Darmstadt

Grants, Awards, and Honors

2018–2020DFG (German Research Foundation) Research Fellowship Grant Foundations and Real-World Aspects of Secure Cryptographic Connections, carried out at UC San Diego and ETH Zurich
2019ACM SIGSAC Doctoral Dissertation Award for Outstanding PhD Theses in Computer and Information Security
2019Dr.-Heinz-Sebiger Dissertation Award on Data Protection and IT Security of the DATEV-Stiftung Zukunft foundation
2019Best paper award at ESORICS 2019 for [12]
2019ERCIM (European Research Consortium for Informatics and Mathematics) STM WG Award for the Best Ph.D. Thesis on Security and Trust Management
2019Runner-up for the CAST/German Informatics Society Doctoral Dissertation Award in IT Security (CAST/GI Promotionspreis IT-Sicherheit)
2017, 2018Collaboration Award 2017 for [13] and 2018 for [5] of the collaborative research center CROSSING at TU Darmstadt
2018Best lecture award for lecture Real World Crypto, TU Darmstadt, summer term 2017 (teaching assistant, award for overall lecture by the computer science student's body, based on evaluations by students)
2015Best student paper award at ACISP 2015 for [22]
2011CAST Advancement Award IT Security (CAST-Förderpreis IT-Sicherheit): 2nd prize in category "Bachelor and Study Theses" for my bachelor thesis [34]
2007–2013Scholarship from the German National Academic Foundation (Studienstiftung des deutschen Volkes)

Professional Activities

May 2019EUROCRYPT 2019 Workshop Co-Chair
Sep 2018Lecturer at the ECRYPT-NET School on Integrating Advanced Cryptography with Applications
Feb–Dec 2011Collaboration in the project "Group Signatures: Privacy-Preserving Authentication Methods", a survey for the German Federal Office for Information Security (BSI), conducted by the Cryptographic Protocols Group at TU Darmstadt
The resulting survey can be found at www.bsi.bund.de.

Program Commitee (PC) Membership

  • CRYPTO 2020, 2019 (International Cryptography Conference)
  • QUIPS 2020 (QUIC Privacy and Security Workshop)
  • SSR 2020 (Security Standardisation Research Conference)

Peer Reviewing for Scientific Conferences and Journals

  • 2020: Journal of Cryptology, ASIACRYPT
  • 2019: EUROCRYPT, ACM CCS, Journal of Cryptology
  • 2018: ACM CCS
  • 2017: EUROCRYPT, PKC, ACISP, Latincrypt
  • 2016: CRYPTO
  • 2015: Latincrypt, ACM CCS
  • 2014: INFOCOM, TCC, ACNS, ASIACRYPT, Elsevier Information Processing Letters
  • 2013: Elsevier Computer Communications Journal

Research Visits

Mar 2017 UC San Diego, La Jolla, CA, USA – Security and Cryptography Group
Host: Prof. Mihir Bellare
Feb 2017 Stanford University, Stanford, CA, USA – Applied Cryptography Group
Host: Prof. Dan Boneh
Jan 2017 Cornell Tech University, New York City, NY, USA – Security Group
Host: Prof. Thomas Ristenpart
Jan 2017 Johns Hopkins University, Baltimore, MD, USA – Information Security Institute
Host: Prof. Matthew D. Green
Jan 2017 IBM T.J. Watson Research Center, Yorktown Heights, NY, USA – Cryptography Research Group
Host: Dr. Hugo Krawczyk
Apr 2016 Ruhr-Universität Bochum, Bochum, Germany – Lehrstuhl für Netz- und Datensicherheit
Hosts: Prof. Dr. Jörg Schwenk and Dr. Tibor Jager
Jun–Jul 2015 Queensland University of Technology, Brisbane, Australia – Information Security Discipline
Host: Senior Lecturer Dr. Douglas Stebila
May 2015 Technische Universität Dresden, Dresden, Germany – Lehrstuhl für Datenschutz und Datensicherheit
Host: Prof. Dr. Thorsten Strufe
Jan 2015 Royal Holloway, University of London, Egham, UK – Information Security Group
Host: Prof. Kenneth G. Paterson

Contributions to Standards, Research Impact, and Media Attention


ETH Zurich

autumn semester 2020 Co-coordination of the seminar Current Topics in Information Security by Srdjan Capkun, Kenny Paterson, and Adrian Perrig
spring semester 2020 Co-coordination of the seminar Current Topics in Cryptography by Kenny Paterson, Dennis Hofheinz, and Ueli Maurer
spring semester 2020 Lecture contribution to the course Applied Cryptography by Kenny Paterson

University of California San Diego

winter quarter 2019 TLS Crypto Seminar

Graduate-level (informal) seminar with both lectures and paper presentations

Technische Universität Darmstadt

winter term 2018/2019 Organization of the graduate-level seminar Reading the Crypto Classics
summer term 2018 Teaching assistant for the lecture Real World Crypto by Marc Fischlin
summer term 2018 Organization of the graduate-level seminar Reading the Crypto Classics
winter term 2017/2018 Organization of the graduate-level seminar Reading the Crypto Classics
summer term 2017 Teaching assistant for the lecture Real World Crypto by Marc Fischlin

(Best lecture award for overall lecture, by the computer science student's body, based on evaluations by students)

winter term 2016/2017 Teaching assistant for the research seminar Research-Oriented Cryptography by Marc Fischlin
winter term 2015/2016 Teaching assistant for the lecture Functional and Object-oriented Programming Concepts (Funktionale und objektorientierte Programmierkonzepte, ex. Grundlagen der Informatik 1) by Marc Fischlin
winter term 2013/2014 Teaching assistant for the lecture Introduction to Computer Science 1 (Grundlagen der Informatik 1) by Marc Fischlin
winter term 2011/2012 Tutor for the lecture Introduction to Cryptography (Einführung in die Kryptographie) by Marc Fischlin


  • Matilda Backendal (Master, Jan–Jun 2019). Puncturable Symmetric KEMs for Forward-Secret 0-RTT Key Exchange.

    Co-Advisor: Thomas Johansson (Lund University, Sweden)

Felix Günther

Dr. rer. nat. Felix Günther

ETH Zurich
Department of Computer Science
Institute of Information Security
Applied Cryptography Group

Postal address:
Institut f. Informationssicherheit, CNB E 104.1
Universitätstrasse 6
8092 Zürich

Phone:+41 44 632 86 47
Office:CNB E 104.1


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