Christopher Brzuska

Office:
Room C210 (CS Building)
Aalto University

Postal Address:
Aalto University, School of Science
P. O. Box 15400
FIN-00076 AALTO

Welcome to the homepage of Chris Brzuska. I am a faculty member of the departments computer science as well as mathematics and systems analysis at Aalto University in Finland. My research area is cryptography and its connections to related areas such as IT security, verification and complexity theory.

Contact

The best way to contact me is usually via eMail chris dot brzuska at aalto dot fi. You can also try to call me, but usually, the attempt to call me is less likely to be successful, since I am strictly offline during research activity, teaching interactions and other personal interactions.

Cryptography at Aalto

You can find more information about cryptography at Aalto here.

Research Resources

I maintain a list of research resources here.

Queer Resources

I maintain a list of queer resources here.

Teaching

In our cryptography courses, we often use the crypto companion. The writing is due to Valtteri Lipiäinen and myself, and it is inspired my numerous doctoral and master students, with very special thanks to Osama Abuzaid for developing and sharing his insights during his internship in 2019. Below, I list past and future courses.

• Winter Term 2025/26 (Teaching period I and II)
  Cryptography
• Winter Term 2025/26 (Teaching period I and II)
  Special Course: Advanced Cryptography (You can take this course in parallel with "Cryptography".)
• Winter Term 2025/26 (Teaching period II)
  Matrix Algebra
• Winter Term 2024/25 (Teaching period I and II)
  Cryptography
• Spring Term 2024 (Teaching period III and IV)
  Course Advanced Topics in Cryptography
• Winter Term 2023/24 (Teaching period II)
  Matrix Algebra
• Winter Term 2023/24 (Teaching period I and II)
  Course Cryptography *(co-taught by Russell W. Lai)*
• Spring Term 2023 (Teaching period III and IV)
  Course Advanced Topics in Cryptography This edition of the course was taught by Russell W. Lai and covered lattice-based cryptography.
• Winter Term 2022/23 (Teaching period I and II)
  Course Cryptography *(co-taught by Russell W. Lai)*
• Spring Term 2022 (Teaching period III and IV)
  Course Advanced Topics in Cryptography
• Winter Term 2021/22 (Teaching period I and II)
  Course Cryptography
• Spring Term 2021 (Teaching period III and IV)
  Course Advanced Topics in Cryptography
• Winter Term 2020/21 (Teaching period I and II)
  Course Cryptography
• Spring Term 2020 (Teaching period III and IV)
  Course Advanced Topics in Cryptography
• Winter Term 2019/20 (Teaching period I and II)
  Course Cryptography and Data Security *(co-taught by Kaisa Nyberg)*
• Spring Term 2019 (Teaching period III and IV)
  Course Advanced Topics in Cryptography
• Winter Term 2018/19 (Teaching period I and II)
  Course Cryptography and Data Security
• Winter Term 2017/18
  Course Introduction to Security *(co-taught by Dieter Gollmann)*
• Summer Term 2017
  Course Cryptography
  Seminar on Real-Life Security of Cryptography: TLS, AES & Elliptic Curves - Standards, Implementations and Attacks
  
• Winter Term 2016/17
  Course Introduction to Security *(co-taught by Dieter Gollmann)*
  Seminar on Secure Messaging
  Seminar on SAT Algorithms
  
• Summer Term 2016
  Course Cryptography
• Winter Term 2015/16
  Course Introduction to Security

Publications

For full references, see DBLP.

Journals

• Towards Fine-Grained One-Way Functions from Strong Average-Case Hardness
  C. Brzuska, G. Couteau
  Journal of Cryptology 2025
  ePrint
• Relations among new CCA security notions for approximate FHE
  C. Brzuska, S. Canard, C. Fontaine, D. H. Phan, D. Pointcheval, M. Renaud, R. Sirdey
  CiC 2025
  ePrint
• Falsifiability, Composability, and Comparability of Game-based Security Models for Key Exchange Protocols
  C. Brzuska, C. Cremers, H. Jacobsen, D. Stebila, W. Warinschi
  Celebrating the Life and Work of Ed Dawson, LNCS, Springer 2025
  ePrint
• Simple Watermarking Pseudorandom Functions from Extractable Pseudorandom Generators
  E. Alpirez Bock, C. Brzuska, R. W. F. Lai
  CiC 2024
  
• On Provable White-Box Security in the Strong Incompressibility Model
  E. Alpirez Bock, C. Brzuska, R. W. F. Lai
  TCHES 2023
  ePrint
• On the Security Goals of White-Box Cryptography
  E. Alpirez Bock, A. Amadori, C. Brzuska, W. Michiels
  TCHES 2020
  ePrint
• White-Box Cryptography: Don't Forget About Grey Box Attacks
  E. Alpirez Bock, J. W. Bos, C. Brzuska, C. Hubain, W. Michiels, C. Mune, E. Sanfelix Gonzalez, P. Teuwen, A. Treff
  Journal of Cryptology 2019
  ePrint
• Arithmetic Cryptography
  B. Applebaum, J. Avron, C. Brzuska
  Journal of the ACM 2017
  ECCC
• Less is More: Relaxed yet Composable Security Notions for Key Exchange
  C. Brzuska, M. Fischlin, N. P. Smart, B. Warinschi, S. C. Williams
  International Journal of Information Security 2013.
  Full Version

Conferences

• Succinct PPRFs via Memory-Tight Reductions
  J. Alwen, C. Brzuska, G. Govinden, P. Harasser, S. Tessaro
  CRYPTO 2025
  Camera-ready version
• Evasive LWE Assumptions: Definitions, Classes, and Counterexamples
  C. Brzuska, I. Woo, A. Ünal
  Asiacrypt 2024
  ePrint
• On Bounded Storage Key Agreement and One-Way Functions
  C. Brzuska, G. Couteau, C. Egger, W. Quach
  TCC 2024
  
• Instantiating the Hash-Then-Evaluate Paradigm: Strengthening PRFs, PCFs, and OPRFs
  C. Brzuska, G. Couteau, C. Egger, P. Karanko, P. Meyer
  SCN 2024
  ePrint
• Breaking DPA-Protected Kyber via the Pair-Pointwise Multiplication
  E. Alpirez Bock, G. Banegas, C. Brzuska, L. Chmielewski, K. Puniamurthy, M. Sorf
  ACNS 2024
  ePrint
• CryptoZoo: A Viewer for Cryptographic Reduction Proofs
  C. Brzuska, C. Egger, K. Puniamurthy
  ACNS 2024
  ePrint
• A Adaptive Distributional Security for Garbling Schemes with O(|x|) online complexity
  E. Alpirez Bock, C. Brzuska, P. Karanko, S. Oechsner, K. Puniamurthy
  Asiacrypt 2023
  ePrint
• A State-Separating Proof for Yao's Garbling Scheme
  C. Brzuska, S. Oechsner
  CSF 2023
  ePrint
• Key-schedule Security for the TLS 1.3 Standard
  C. Brzuska, A. Delignat-Lavaud, C. Egger, C. Fournet, K. Kohbrok, M. Kohlweiss
  Asiacrypt 2022
  ePrint (long version, 119 pages)
  short version (40 pages and contains everything except for reductions from modular to standard assumptions, very nice version :-))
  5-minutes talk by Chris on protocol insights 20-minutes talk by Christoph on the proof
• Towards Fine-Grained One-Way Functions from Strong Average-Case Hardness
  C. Brzuska, G. Couteau
  Eurocrypt 2022
  ePrint
• Security Analysis of the MLS Key Derivation
  C. Brzuska, E. Cornelissen, K. Kohbrok
  Security and Privacy 2022.
  ePrint
  1-minute talk by Chris
  15-minutes talk by Eric
• On derandomizing Yao's Weak-to-Strong OWF Comstruction
  C. Brzuska, G. Couteau, P. Karanko, F. Rohrbach
  TCC 2021
  ePrint
• Security Reductions for White-Box Key-Storage in Mobile Payments
  E. Alpirez Bock, C. Brzuska, M. Fischlin, C. Janson, W. Michiels
  ASIACRYPT 2020
  ePrint
• Doubly half-injective PRGs for incompressible white-box cryptography
  E. Alpirez Bock, A. Amadori, J. W. Bos, C. Brzuska, W. Michiels
  CT-RSA 2019
  ePrint
• State Separation for Code-Based Game-Playing Proofs
  C. Brzuska, A. Delignat-Lavaud, C. Fournet, K. Kohbrok, M. Kohlweiss
  ePrint
  (last updated on Dec 05, 2018)
  ASIACRYPT 2018
• On the Ineffectiveness of Internal Encodings - Revisiting the DCA Attack on White-Box Cryptography
  E. Alpirez Bock, C. Brzuska, W. Michiels, A. Treff
  ePrint
  ACNS 2018
• A Modular Security Analysis of EAP and IEEE 802.11
  C. Brzuska, H. Jacobsen
  ePrint
  PKC 2017
• On Statistically Secure Obfuscation with Approximate Correctness
  ePrint
  Z. Brakerski, C. Brzuska, N. Fleischhacker
  CRYPTO 2016
• Downgrade Resilience in Key-Exchange Protocols
  ePrint
  K. Bhargavan, C. Brzuska, C. Fournet, M. Green, M. Kohlweiss, S. Zanella-Beguelin
  Security and Privacy 2016.
• Safely Exporting Keys from Secure Channels - On the Security of EAP-TLS and TLS Key Exporters
  C. Brzuska, H. Jacobsen, D. Stebila
  ePrint
  EUROCRYPT 2016.
• Random Oracle Uninstantiability from Indistinguishability Obfuscation
  ePrint
  C. Brzuska, P. Farshim, A. Mittelbach
  TCC 2015.
• On Basing Size-Verifiable One-Way Functions on NP-Hardness
  ECCC
  A. Bogdanov, C. Brzuska
  See also O. Goldreich's comments.
  TCC 2015.
• Arithmetic Cryptography
  B. Applebaum, J. Avron, C. Brzuska
  ECCC
  See also O. Goldreich's comments.
  ITCS 2015.
• Indistinguishability Obfuscation versus Multi-Bit Point Obfuscation with Auxiliary Input
  ePrint
  C. Brzuska, A. Mittelbach
  ASIACRYPT 2014.
• Using Indistinguishability Obfuscation via UCEs
  ePrint
  C. Brzuska, A. Mittelbach
  ASIACRYPT 2014.
• Indistinguishability Obfuscation and UCEs: The Case of Computationally Unpredictable Sources
  ePrint
  C. Brzuska, P. Farshim, A. Mittelbach
  CRYPTO 2014.
• Notions of Black-Box Reductions, Revisited
  Full Version
  P. Baecher, C. Brzuska, M. Fischlin
  ASIACRYPT 2013.
• Reset Indifferentiability and its Consequences
  Full Version
  P. Baecher, C. Brzuska, A. Mittelbach
  ASIACRYPT 2013.
• An Analysis of the EMV Channel Establishment Protocol
  Full Version
  C. Brzuska, N. P. Smart, B. Warinschi, G. J. Watson.
  CCS 2013.
• Efficient and Perfectly Unlinkable Sanitizable Signatures without Group Signatures
  C. Brzuska, H. C. Pöhls, K. Samelin
  EuroPKI 2013.
• Non-Interactive Public Accountability for Sanitizable Signatures
  C. Brzuska, H. C. Pöhls, K. Samelin
  EuroPKI 2012.
• TLS, PACE, and EAC:
  A Cryptographic View at Modern Key Exchange Protocols
  C. Brzuska, Ö. Dagdelen, M. Fischlin
  Sicherheit 2012.
• Composability of Bellare-Rogaway Key Exchange Protocols
  C. Brzuska, M. Fischlin, Bogdan Warinschi, S. C. Williams
  CCS 2011.
• Physically Uncloneable Functions in the Universal Composition Framework
  Full Version
  C. Brzuska, M. Fischlin, H. Schröder, S. Katzenbeisser
  CRYPTO 2011.
• Redactable Signatures for Tree-Structured Data:
  Definitions and Constructions
  C. Brzuska, H. Busch, Ö. Dagdelen, M. Fischlin, M. Franz, S. Katzenbeisser, M. Manulis, C. Onete, A. Peter, B. Poettering, D. Schröder
  ACNS 2010.
• Unlinkability of Sanitizable Signatures
  Full Version
  C. Brzuska, M. Fischlin, A. Lehmann, D. Schröder
  PKC 2010.
• Sanitizable Signatures:
  How to Partially Delegate Control for Authenticated Data
  C. Brzuska, M. Fischlin, A. Lehmann, D. Schröder
  BIOSIG 2009.
• Security of Sanitizable Signatures Revisited
  Full Version
  C. Brzuska, M. Fischlin, T. Freudenreich, A. Lehmann, M. Page, J. Schelbert, D. Schröder, F. Volk
  PKC 2009.

Theses

• On the Foundations of Key-Exchange
  PhD Thesis
  C. Brzuska
  PhD Thesis, tuprints, 2013.
• On Thrall's Third Conjecture
  C. Brzuska
  Master Thesis, unpublished, 2010

PhD Students (current)

• Kirthivaasan Puniamurthy, since February 2021
• Ivy Woo, since July 2022 Homepage

PhD Students (former)

• Pihla Karanko, September 2019 - September 2025
• Ameet Gadekar, graduated 2024 , co-advised by Parinya Chalermsook (Aalto CS)
• Georgios Giantamidis, 2019 - August 2023, co-advised by Stavros Tripakis (Northeastern University)
• Konrad Kohbrok, July 2016 - July 2023, co-advised by Markulf Kohlweiss (MSR Cambridge/University of Edinburgh) and Antoine Délignat-Lavaud (MSR Cambridge)
• Alessandro Amadori, September 2016 - April 2021, co-advises by Wil Michiels (NXP Eindhoven), Boris Skoric (TU Eindhoven), TU Eindhoven, examiners: Bart Preneel (KU Leuven), Leijla Betina (Radboud University), Berry Schoenemakers (TU Eindhoven), Peter Roelse (Irdeto), Wil Michiels, Chris Brzuska
• Estuardo Alpirez Bock, November 2016 - June 2020, co-advised by Wil Michiels (NXP Eindhoven), Aalto University, examiners: Pascal Paillier (CryptoExperts), Andrey Boddanov (DTU)

Post-doctoral researchers

• Estuardo Alpirez Bock, July 2020 - October 2021

Program Committees

• 2025: EUROCRYPT, ASIACRYPT (Area Chair), CSF
• 2024: EUROCRYPT, TCC
• 2023: EUROCRYPT, CRYPTO, TCC
• 2022: S&P, PKC, CHES
• 2021: S&P, CHES, TCC, CT-RSA, ACNS, INDOCRYPT
• 2020: S&P, CT-RSA, PKC, TCC, INDOCRYPT
• 2019: PKC, TCC
• 2018: EUROCRYPT, CRYPTO, ASIACRYPT, PKC, SICHERHEIT
• 2017: EUROCRYPT, ASIACRYPT, ESORICS, INDOCRYPT
• 2016: TCC-A, EUROCRYPT, TCC-B, CCS Posters, CROSSFYRE, IFIP SEC, AsiaPKC, SECPID
• 2015: ACNS, IFIP SEC
• 2014: ACNS

Review Activities (until 2017)

• 2017: PKC
• 2016: CRYPTO, FOCS, IEEE Security and Privacy journal, Siam Journal of Computing, SCN
• 2015: TCC, EUROCRYPT, CCC, ICALP
• 2014: TCC, EUROCRYPT, Security & Privacy, CRYPTO, ICALP, ASIACRYPT
• 2013: PKC, EUROCRYPT, CCC, ACISP, T-IFS, ESORICS, CCS, ASIACRYPT
• 2012: CT-RSA, EUROCRYPT, ACNS, CRYPTO, CCS, ASIACRYPT, T-IFS
• 2011: PKC, FC, EUROCRYPT, CRYPTO, CCS, ASIACRYPT, ProvSec, CCSW
• 2010: CT-RSA, ASIACRYPT

Organization

• 2025: ProTeCS : Workshop on Proofs and Proof Techniques for Cryptographic Security, co-organized with Sabine Oechsner, co-located with EUROCRYPT, Location: Madrid, Spain
• 2020: WoDUP : Workshop on developing, using and teaching cryptographic proofs, co-organized with Markulf Kohlweiss, Sabine Oechsner, co-located with EUROCRYPT, Location: Zaghreb, Croatia (postponed due to COVID)
• 2019: WhibOx II , co-organized with Pascal Paillier, co-located with EUROCRYPT, Location: Darmstadt, Germany
• 2018: CryptoSymposium , part of the COST CryptoAction, Location: Sutamore, Montenegro
• 2017: CryptoSymposium , co-located with PKC and part of the COST CryptoAction, Location: Amsterdam, Netherlands
  73. Theorietag , co-organized with Petra Berenbrink (Uni Hamburg) and Peter Kling (Uni Hamburg), Location: TU Hamburg, Germany
• 2016: Workshop on the analysis of real-life protocols as part of the COST CryptoAction, Location: Budapest, Hungary
• 2015: Workshop on the analysis of real-life protocols, co-located with Eurocrypt 2015 and part of the COST CryptoAction, Location: Sofia, Bulgaria

Short CV

Until March 2018, I was a junior professor at TU Hamburg in Germany and held the chair for IT Security Analysis in collaboration with and supported by NXP Semiconductors. Until September 2015, I was a post-doctoral researcher at Microsoft Research Cambridge, UK. Until September 2014, I was a post-doctoral researcher at Tel-Aviv University working with Benny Applebaum and Iftach Haitner. Until October 2012, I was a PhD student advised by Marc Fischlin at TU Darmstadt. During my PhD, I also visited Russell Impagliazzo at IAS from October 2011 to March 2012. Before, I studied mathematics in Duisburg-Essen, Bordeaux and Darmstadt with the key aspects cryptography, logic and lattice theory.

Awards

• Distinguished PC Member Award EUROCRYPT 2024
• Best PC Member Award ASIACRYPT 2018
• Best PC Member Award CRYPTO 2018
• Vodafone Förderpreis 2014
  Vodafonestiftung
  Pressemeldung
• GDD Wissenschaftspreis 2013
  Gesellschaft für Datenschutz und Datensicherheit e.V. (GDD)
  Pressemeldung
• Nominiert für den CAST Promotionspreis IT-Sicherheit 2013
  Competence Center for Applied Security Technology, CAST e.V.
  Pressemeldung

News

• Kauppalehti, January 2019 Link
• Hamburger Abendblatt März 2017
  Artikel
• Tageblatt Februar 2017
  Artikel
• Spektrum Mai 2016
  Artikel
• Hamburger Abendblatt Februar 2016
  Artikel
• MintStudium Hamburg Januar 2016
  Artikel
• Harburg Aktuell Oktober 2015
  Artikel
• Hamburger Abendblatt Oktober 2015
  Artikel

Last update: 2025-04-11