Rohitkumar R. Upadhyay

About Me

I am a Postdoctoral Researcher at Inria, working with the CAPSULE Team in Rennes, France, under the supervision of Prof. Pierre-Alain Fouque and Dr. Yixin Shen. My core research focus is privacy-preserving computation and post-quantum cryptography — building secure, efficient protocols using Fully Homomorphic Encryption (FHE), Secure Multi-Party Computation (MPC), and Zero-Knowledge Proofs (ZKPs), grounded in strong mathematical foundations.

My research spans the design and analysis of FHE-based and MPC-based cryptographic schemes, verifiable computation, post-quantum digital signatures, and their real-world applicability in areas such as cloud security, privacy-preserving machine learning, and secure data sharing. During my time working at QNu Labs, I also gained industry exposure to NIST PQC standards (ML-KEM, ML-DSA) and worked on related implementation and analysis tasks — broadening my perspective on the gap between theory and deployment.

I completed my Ph.D. in Mathematics at MNNIT Allahabad (Prayagraj) (2022–2025) and was selected as one of three global laureates for the Post-Quantum Algebraic Cryptography trimester at the Institut Henri Poincaré, Paris. I am also an alumnus of the Mathematics Training and Talent Search (MTTS) programme — an experience that deeply shaped my love for mathematical thinking and exposition.

Beyond research, I genuinely love teaching. I find great joy in making deep mathematical and cryptographic ideas accessible — from undergraduate classrooms to international workshops. The MTTS pedagogy of inquiry-based, student-centred learning has been a lasting influence on my teaching methodology, and I continue to bring that spirit into every lecture, seminar, and mentoring interaction.

Education

• Ph.D. in Mathematics (2022 – 2025)
  MNNIT Allahabad, India
  Thesis: A Study of Secure Computation using Post-Quantum Cryptography
  Advisor: Dr. Sahadeo Padhye
  • Proposed efficient Dynamic Multi-Party FHE frameworks based on GSW and FHEW, enabling scalable secure computation in decentralized environments.
  • Developed a multi-key FHE scheme over integers with batching mechanisms for parallel operations in large-scale MPC.
  • Designed FHE-Pro, integrating Proxy Re-encryption to enable non-interactive key generation and reduced communication complexity.
  • Optimized homomorphic multiplication using bit decomposition, reducing computational complexity from quadratic to linear for structured data and PPML.
  • Formalized SNARK-driven verifiable FHE mechanisms to ensure result integrity and privacy in outsourced cloud computations.
  • Investigated VOLE-in-the-Head for constructing efficient post-quantum digital signatures.
• M.Sc. in Mathematics (2017 – 2019)
  University of Mumbai, India
• B.Sc. in Mathematics (2014 – 2017)
  NES Ratnam Degree College, Mumbai, India

Experience

• Postdoctoral Researcher
  Inria — CAPSULE Team, Rennes, France · September 2026 – Present
  Supervisors: Prof. Pierre-Alain Fouque and Dr. Yixin Shen
  • Researching privacy-preserving and verifiable computation using Fully Homomorphic Encryption (FHE), Secure Multi-Party Computation (MPC), and Zero-Knowledge Proofs (ZKPs).
  • Investigating efficient cryptographic protocols at the intersection of mathematical foundations, secure computation, and practical implementation.
  • Developing approaches for verifiable and privacy-preserving computation in collaborative and outsourced settings.
• Applied Cryptographer
  QNu Labs, Delhi, India · April 2026 – August 2026
• Cryptography Analyst
  QNu Labs, Bangalore, India · June 2025 – March 2026
  • Worked on algorithmic analysis and implementation tasks related to constant-time ML-KEM and ML-DSA, gaining exposure to physical leakage considerations in PQC deployments.
  • Contributed to evaluation of masking and blinding approaches for post-quantum cryptographic primitives.
  • Designed MPC and FHE-based protocol proposals for secure data sharing, focusing on reducing communication overhead and improving scalability.
  • Studied and evaluated NIST PQC standards and global benchmarks to support internal transition planning.
• Trimester Laureate
  Institut Henri Poincaré (IHP), Paris, France · September – December 2024
  Selected as one of three global laureates for the IHP Trimester on Post-Quantum Algebraic Cryptography; worked with Prof. Ludovic Perret on MPC-in-the-Head-based signatures.
• Assistant Professor
  KET's Vinayak Ganesh Vaze College, Mumbai, India · 2019 – 2022
  • Taught undergraduate courses including Topology, Number Theory, and Cryptography.

Technical Skills

• Privacy-Preserving Computation: FHE (OpenFHE, SEAL, Lattigo), MPC (MP-SPDZ), ZKP (libsnark, Circom), Proxy Re-encryption, Secret Sharing
• Post-Quantum Cryptography: Lattice-based schemes, NIST PQC standards (ML-KEM, ML-DSA); libraries: PQClean, liboqs
• Programming Languages: C/C++ (Advanced), Python (Advanced — SageMath, NumPy, SciPy), Go (Intermediate), LaTeX
• Developer Tools & Platforms: Git, GitHub, Linux/Unix, VS Code
• Mathematics & Theory: Lattice-based cryptography, number theory, algebra, computational complexity
• Teaching & Communication: Undergraduate & graduate instruction, workshop facilitation, technical writing, MTTS inquiry-based pedagogy
• Languages: English (professional), Hindi (native), French (beginner)

Research Publications

1. 2025. Upadhyay, R.R., Padhye, S., Sahu, R.A., Saraswat, V.
   Towards Privacy and Integrity: SNARK-Driven Verifiable FHE for Outsourced Computation.
   ACNS 2025 Workshops. Springer LNCS.
2. 2025. Upadhyay, R.R., Padhye, S., Saraswat, V.
   A Non-Interactive and Dynamic Multi-Party FHE Scheme Based on FHEW.
   Peer-to-Peer Networking and Applications. (SCIE).
3. 2025. Upadhyay, R.R., Padhye, S.
   A Non-Interactive and Secure Dynamic Multi-Party FHE Scheme.
   International Journal of Information Security. (SCIE).
4. 2025. Kumar, R., Dabral, A., Upadhyay, R.R.
   Cryptanalysis of a Lattice-Based Blind Ring Signature Scheme.
   National Academy Science Letters. (SCIE).
5. 2025. Upadhyay, R.R., Padhye, S.
   SoK: Digital Signatures from VOLEitH.
   Human-2025 Symposium. Best Paper Award.
6. 2025. Upadhyay, R.R., Padhye, S.
   Privacy-Preserving Image Retrieval Based on Threshold Secret Sharing.
   Human-2025 Symposium.
7. 2024. Upadhyay, R.R., Padhye, S.
   Efficient and Secure MPC Through Integration of FHE and Proxy Re-Encryption.
   SN Computer Science.
8. 2024. Upadhyay, R.R., Padhye, S.
   Advancements in FHE over the Integers: A Comprehensive Survey and Analysis.
   Surveys in Mathematics and its Applications.
9. 2023. Upadhyay, R.R., Padhye, S.
   Enhancing FHE Over the Integers: Beyond Binary Numbers and Batch Processing.
   ICCNSML 2023. Springer LNNS.
10. 2023. Upadhyay, R.R., Padhye, S.
    Multi-Key Fully Homomorphic Encryption Scheme Over the Integers.
    REDCYSEC 2023. Springer LNNS.

Full list on Google Scholar.

Selected Invited Talks and Panels

• Invited talk: Post-Quantum Cryptography Across the Data Lifecycle: In Transit, At Rest, and In Computation at ICMMCISD-2026, VIT Vellore (June 3–5, 2026).
• Invited lecture: Alumni Lecture Series in Mathematics, University of Mumbai — A Gentle Introduction to Modern Cryptography (April 2026).
• Expert lectures (×3): VIT Vellore (September 10, 2025) — career pathways in cryptography; statistics in post-quantum cryptography; discrete mathematical approaches to PQC (200+ B.Tech./Integrated M.Tech students).
• Panelist: Industry Panel Discussion on “PQC Transition Strategy” at Future Proofing Through Quantum Resilience, SETS, Chennai (July 18, 2025; jointly organized by SETS, C-DAC, and CCA India).
• Conference talk: Presented Towards Privacy and Integrity: SNARK-Driven Verifiable FHE for Outsourced Computation at PrivCrypt 2025 (ACNS 2025 workshops), Munich, Germany (June 24, 2025).
• Symposium talk: Presented SoK: Digital Signatures from VOLEitH at the 3rd Doctoral Symposium on Human-Centered Computing (Human-2025), Kalyani, West Bengal (Best Paper Award, March 28, 2025).
• Student talk: Secure Computation at the Introductory Summer School in Cryptography, IESC Cargèse, Corsica (September 9–13, 2024; IHP trimester program).
• Invited talk: Secure Computation (FHE, MPC, and hybrid FHE–MPC) at the National Instructional Workshop on Cryptology (NIWC 2024), MNNIT Allahabad (July 2024).
• Tech talk: Secure Multi-Party Computation: A Gentle Introduction, SparQ series, QNu Labs (May 2024).
• Student talk: Secure computation with Fully Homomorphic Encryption at the CIMPA Research School on Post-Quantum Cryptography, Pondicherry University (December 11–21, 2023).

Awards & Grants

• June 2025 — Financial Support for PrivCrypt 2025 (CIMPA, CRSI, BOSCH), Munich, Germany.
  For presenting Towards Privacy and Integrity: SNARK-Driven Verifiable FHE for Outsourced Computation at PrivCrypt 2025 (ACNS 2025 workshops).
• March 2025 — Best Paper Award, 3rd Doctoral Symposium on Human-Centered Computing (Human-2025), for SoK: Digital Signatures from VOLEitH.
• March 2025 — Student Stipend (IACR), Real World Crypto Symposium (RWC) 2025, Sofia, Bulgaria.
• March 2025 — Student Stipend, TPMPC 2025, IISc Bangalore.
• September – December 2024 — CIMPA Fellowship / Trimester Laureate, Institut Henri Poincaré (IHP), Paris, France.
• December 2023 — CIMPA Financial Support, CIMPA Research School, Pondicherry University, India.
• 2022 — CSIR-UGC JRF and NET Qualification, CSIR, India.
• 2021, 2022 — GATE Qualified, Ministry of Education, India.

Contact

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Institutional: rohitkumar.upadhyay@inria.fr

Personal: math4rohit@gmail.com