Summary of research activities in cryptography
Since 1998, my research in cryptography has developed along three directions: cryptanalysis, new constructions and algorithms, and side-channel attacks and countermeasures.
In cryptanalysis, my early contributions focused on RSA, including practical attacks on the ISO 9796-1 and ISO 9796-2 signature standards. I also contributed to the analysis of advanced algebraic constructions, including attacks on GGH15 multilinear maps, and to related algorithmic complexity results, such as a polynomial-time solution to the hidden subset-sum problem.
In new constructions and algorithms, I worked on efficient primitives with provable security guarantees. I advocated the use of indifferentiability for hash-function design, with results on Merkle-Damgard-style constructions, and showed how to perform indifferentiable hashing into elliptic curves. I also contributed to earlier work on fully homomorphic encryption over the integers, including shorter public keys and batching techniques, as well as to a more recent bootstrapping approach for approximate-arithmetic FHE based on the CKKS scheme. In addition, I contributed to multilinear-map constructions, notably CLT13, and to a concrete secure multiparty non-interactive Diffie-Hellman construction designed to resist known attacks.
In side-channel security, my work spans more than two decades, from early DPA-resistant implementations to recent high-order masking for post-quantum schemes. Over this period, I contributed to both side-channel attacks and practical countermeasures for elliptic-curve cryptography, block ciphers, and lattice-based cryptography. An important part of this research concerns efficient masking techniques, including high-order protections for lookup tables and conversion algorithms between Boolean and arithmetic representations. More recently, this line of work led to advances for the implementation of post-quantum schemes such as Kyber, NTRU, and Dilithium (TCHES 2022-2024), with improved gadgets tailored to lattice-based operations. On the theoretical side, I also contributed to foundations of side-channel countermeasures, through work on formal verification and improved constructions in the probing model, including wire shuffling with linear complexity in the number of probes (CRYPTO 2021), as well as results on random probing security.
Overall, I view my research as a bridge between theory and practice. I have often built on theoretical breakthroughs by other researchers and developed algorithmic optimizations to make their ideas more practical. In this sense, my work centers on the design and analysis of algorithms, through new constructions, improved realizations of existing constructions, cryptanalytic methods, and side-channel countermeasures.