International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Suparna Kundu

Publications

Year
Venue
Title
2024
TCHES
Carry Your Fault: A Fault Propagation Attack on Side-Channel Protected LWE-based KEM
Post-quantum cryptographic (PQC) algorithms, especially those based on the learning with errors (LWE) problem, have been subjected to several physical attacks in the recent past. Although the attacks broadly belong to two classes – passive side-channel attacks and active fault attacks, the attack strategies vary significantly due to the inherent complexities of such algorithms. Exploring further attack surfaces is, therefore, an important step for eventually securing the deployment of these algorithms. Also, it is mportant to test the robustness of the already proposed countermeasures in this regard. In this work, we propose a new fault attack on side-channel secure masked implementation of LWE-based key-encapsulation mechanisms (KEMs) exploiting fault propagation. The attack typically originates due to an algorithmic modification widely used to enable masking, namely the Arithmetic-to-Boolean (A2B) conversion. We exploit the data dependency of the adder carry chain in A2B and extract sensitive information, albeit masking (of arbitrary order) being present. As a practical demonstration of the exploitability of this information leakage, we show key recovery attacks of Kyber, although the leakage also exists for other schemes like Saber. The attack on Kyber targets the decapsulation module and utilizes Belief Propagation (BP) for key recovery. To the best of our knowledge, it is the first attack exploiting an algorithmic component introduced to ease masking rather than only exploiting the randomness introduced by masking to obtain desired faults (as done by Delvaux [Del22]). Finally, we performed both simulated and electromagnetic (EM) fault-based practical validation of the attack for an open-source first-order secure Kyber implementation running on an STM32 platform.
2021
TCHES
Scabbard: a suite of efficient learning with rounding key-encapsulation mechanisms 📺
In this paper, we introduce Scabbard, a suite of post-quantum keyencapsulation mechanisms. Our suite contains three different schemes Florete, Espada, and Sable based on the hardness of module- or ring-learning with rounding problem. In this work, we first show how the latest advancements on lattice-based cryptographycan be utilized to create new better schemes and even improve the state-of-the-art on post-quantum cryptography. We put particular focus on designing schemes that can optimally exploit the parallelism offered by certain hardware platforms and are also suitable for resource constrained devices. We show that this can be achieved without compromising the security of the schemes or penalizing their performance on other platforms.To substantiate our claims, we provide optimized implementations of our three new schemes on a wide range of platforms including general-purpose Intel processors using both portable C and vectorized instructions, embedded platforms such as Cortex-M4 microcontrollers, and hardware platforms such as FPGAs. We show that on each platform, our schemes can outperform the state-of-the-art in speed, memory footprint, or area requirements.