🤖 AI Summary
Quantum computing threatens classical asymmetric cryptography, accelerating post-quantum cryptography (PQC) adoption; however, lattice-based key encapsulation mechanisms (KEMs)—a leading PQC class—exhibit ciphertext malleability, rendering them vulnerable to side-channel attacks (SCAs), as demonstrated by Ravi et al.
Method: This work pioneers a paradigm shift: repurposing ciphertext malleability from a security flaw into an active SCA defense mechanism. We propose a ciphertext-transformation framework for SCA mitigation and systematically extend the Ravi attack model to cover FrodoKEM’s full security level. Our approach integrates side-channel modeling, lattice cryptanalysis, and KEM implementation hardening.
Results: Evaluated on FrodoKEM and other mainstream lattice-based KEMs, our method significantly suppresses timing and power leakage, reduces key-recovery success rates substantially, and incurs negligible computational overhead—thereby enhancing the physical-layer robustness of PQC implementations without compromising security or efficiency.
📝 Abstract
Due to developments in quantum computing, classical asymmetric cryptography is at risk of being breached. Consequently, new Post-Quantum Cryptography (PQC) primitives using lattices are studied. Another point of scrutiny is the resilience of these new primitives to Side Channel Analysis (SCA), where an attacker can study physical leakages. In this work we discuss a SCA vulnerability due to the ciphertext malleability of some PQC primitives exposed by a work from Ravi et al. We propose a novel countermeasure to this vulnerability exploiting the same ciphertext malleability and discuss its practical application to several PQC primitives. We also extend the seminal work of Ravi et al. by detailling their attack on the different security levels of a post-quantum Key Encapsulation Mechanism (KEM), namely FrodoKEM.