I'm a postdoc in the cryptographic engineering group led by Peter Schwabe at MPI-SP. My work concerns vulnerabilities and attacks arising from the post-quantum migration effort. This includes, but is not limited to, side-channel and fault attacks on lattice-based schemes.

I obtained my Master's of Mathematics from the University of Munich in 2020. During my Master's I focused on algebraic number theory and algebraic geometry. From 2014 to 2020, I was a working student at Infineon; in my last two years as a working student, I was supervised by Thomas Pöppelmann. In 2024, I obtained my PhD from Universität der Bundeswehr in cooperation with Infineon Technologies supervised by Gabi Dreo, Thomas Pöppelmann, and Peter Pessl. My committee consisted of Gabi Dreo, Mark Manulis, Eirini Ntoutsi, Christof Paar, and Arno Wacker.

• Zhenzhi Lai, Ruiyi Zhang, Zhiyuan Zhang, Julius Hermelink, Michael Schwarz, Van-Thuan Pham, and Udaya Parampalli. You Only Decapsulate Once: Ciphertext-Independent Single-Trace Passive Side-Channel Attacks on HQC. Cryptology ePrint Archive, Report 2025/2162. 2025. URL: https://eprint.iacr.org/2025/2162.

• Julius Hermelink, Erik Mårtensson, Maggie Tran. Noise-Tolerant Plaintext-Checking Oracle Attacks – A Soft-Analytic Approach Applied to ML-KEM. Cryptology ePrint Archive, Report 2025/1496. 2025. URL: https://eprint.iacr.org/2025/1496.

• Dina Hesse, Jakob Feldtkeller, Tim Güneysu, Julius Hermelink, Georg Land, Markus Krausz, Jan Richter-Brockmann. t-Probing (In-)Security - Pitfalls on Noise Assumptions. Cryptology ePrint Archive, Report 2025/1202. 2025. URL: https://eprint.iacr.org/2025/1202.

• Julius Hermelink, Kai-Chun Ning, Richard Petri. Finding and Protecting the Weakest Link - On Side-Channel Attacks on y in Masked ML-DSA. In: Advances in Cryptology – CRYPTO 2025, Part V. Ed. by Y. T. Kalai and S. F. Kamara. Vol. 16004. Lecture Notes in Computer Science. Santa Barbara, CA, USA: Springer, Cham, Switzerland, Aug. 2025, pp. 3–37. DOI: 10.1007/978-3-032-01901-1_1.

• Julius Hermelink, Silvan Streit, Erik Mårtensson, and Richard Petri. A Generic Framework for Side-Channel Attacks Against LWE-Based Cryptosystems. In: Advances in Cryptology – EUROCRYPT 2025, Part VIII. Ed. by S. Fehr and P.-A. Fouque. Vol. 15608. Lecture Notes in Computer Science. Madrid, Spain: Springer, Cham, Switzerland, May 2025, pp. 3–32. DOI: 10.1007/978-3-031-91101-9_1.

• Julius Hermelink, Kai-Chun Ning, Richard Petri, and Emanuele Strieder. The Insecurity of Masked Comparisons: SCAs on ML-KEM’s FO-Transform. In: ACM CCS 2024: 31st Conference on Computer and Communications Security. Ed. by B. Luo, X. Liao, J. Xu, E. Kirda, and D. Lie. Salt Lake City, UT, USA: ACM Press, Oct. 2024, pp. 2430–2444. DOI: 10.1145/3658644.3690339.

• Julius Hermelink, Erik Mårtensson, Simona Samardjiska, Peter Pessl, and Gabi Dreo Rodosek. Belief Propagation Meets Lattice Reduction: Security Estimates for Error-Tolerant Key Recovery from Decryption Errors. In: IACR Transactions on Cryptographic Hardware and Embedded Systems 2023.4 (2023), pp. 287–317. DOI: 10.46586/tches.v2023.i4.287-317.

• Julius Hermelink, Silvan Streit, Emanuele Strieder, and Katharina Thieme. Adapting Belief Propagation to Counter Shuffling of NTTs. In: IACR Transactions on Cryptographic Hardware and Embedded Systems 2023.1 (2023), pp. 60–88. DOI: 10.46586/tches.v2023.i1.60-88.

• Julius Hermelink, Peter Pessl, and Thomas Pöppelmann. Fault-Enabled Chosen-Ciphertext Attacks on Kyber. In: Progress in Cryptology - INDOCRYPT 2021: 22nd International Conference in Cryptology in India. Ed. by A. Adhikari, R. Küsters, and B. Preneel. Vol. 13143. Lecture Notes in Computer Science. Jaipur, India: Springer, Cham, Switzerland, Dec. 2021, pp. 311–334. DOI: 10.1007/978-3-030-92518-5_15.

• Mike Hamburg, Julius Hermelink, Robert Primas, Simona Samardjiska, Thomas Schamberger, Silvan Streit, Emanuele Strieder, and Christine van Vredendaal. Chosen Ciphertext k-Trace Attacks on Masked CCA2 Secure Kyber. In: IACR Transactions on Cryptographic Hardware and Embedded Systems 2021.4 (2021), pp. 88–113. ISSN: 2569-2925. DOI: 10.46586/tches.v2021.i4.88-113.

• Julius Hermelink, Thomas Pöppelmann, Marc Stöttinger, Yi Wang, and Yong Wan. Quantum safe authenticated key exchange protocol for automotive application. In: 18-th escar Europe : The World’s Leading Automotive Cyber Security Conference (Konferenzveröffentlichung). 2020. DOI: 10.13154/294-7549.

• CRYTPO 2026
• TCHES 2026
• ACNS 2026
• PQCrypto 2026
• PQCrypto 2025
• CT-RSA 2025
• ACNS 2025
• ArcticCrypt 2025
• TCHES 2025 (Issues 1-4)
• TCHES 2024 (Issues 2-4)

• Asiacrypt 2025
• Crypto 2025
• Eurocrypt 2024
• Transactions on Computers
• EURASIP

• Side-Channel Analysis of Lattice-Based Schemes. Talk at the JHAS PQC subgroup. September 2025. Slides
• Side-Channel and Fault Attacks on Lattice-Based Cryptography. Talk at the MPI-SP ``Symposium on Challenges in a Digitalized Society''. July 2025. Slides
• A Generic Framework for Side-Channel Attacks against LWE-based Cryptosystems. Conference Talk at Eurocrypt 2025. May 2025. Slides
• Side-Channel Analysis of Post-Quantum Schemes. Talk at the School of Computer Science at the University of Birmingham. April 2025. Slides
• Side-Channel and Fault Attacks on Modern Lattice-Based Cryptography. Talk at my old group at Infineon Technologies AG. November 2024. Slides
• The Insecurity of Masked Comparisons: SCAs on ML-KEM's FO-Transform. Conference Talk at CCS 2024. October 2024. Slides
• Side-Channel and Fault Attacks on Modern Lattice-Based Cryptography. PhD Defense. March 2024. Slides
• Belief Propagation Meets Lattice Reduction: Security Estimates for Error-Tolerant Key Recovery from Decryption Errors. Conference Talk at CHES 2023. October 2023. Slides
• Decryption Errors and Implementation Attacks on Kyber. Seminar Talk at the University of Lübeck. April 2023. Slides
• Fault-Enabled Chosen-Ciphertext Attacks on Kyber. Lunch Talk at the Security Engineering Group at Ruhr University Bochum. March 2022. Slides (updated)
• Fault-Enabled Chosen-Ciphertext Attacks on Kyber. Lunch Talk at the DiS department at Radboud University. March 2022. Slides: see above.
• Fault-Enabled Chosen-Ciphertext Attacks on Kyber. Conference Talk at Indocrypt 2021. December 2021. Slides

• Side-Channel and Fault Attacks in Modern Lattice-Based Cryptography. Supervisor: Prof. Dr. Gabi Dreo.
• Identifying Frobenius elements and calculating Galois Gauss sums. Master's Thesis. Supervisor: Prof. Dr. Werner Bley.
• Klassifikation Quadratischer Formen über den rationalen Zahlen. Bachelor's Thesis. Supervisor: Prof. Dr. Andreas Rosenschon.