Rudraksh: A compact and lightweight post-quantum key-encapsulation mechanism

2025-01-23

IACR Cryptology ePrint Archive

AI Summary

To address quantum threats against resource-constrained IoT devices, this paper proposes a lightweight lattice-based key encapsulation mechanism (LWE-KEM). Methodologically, it introduces the first systematic optimization of LWE parameters—including polynomial dimension, modulus structure, modular reduction algorithms, and error distribution—tailored for hardware efficiency. It innovatively substitutes ASCON for Keccak in PRNG and hash functionalities, significantly improving cryptographic primitive performance. Furthermore, it integrates a CCA-secure construction with joint area–timing optimization targeting FPGA implementations. Experimental results demonstrate that, at NIST Level I security (≥AES-128), the proposed design reduces FPGA logic area by approximately 3× compared to the most compact Kyber implementation, achieves a 63%–76% higher operating frequency, and improves the time–area product by 2×—yielding substantial gains in hardware energy efficiency.

Technology Category

• Machine Learning: Hardware-aware ML
• Application Domains: Internet of Things, Sensor Networks & Smart Cities
• Search and Optimization: Learning to Search

Application Category

• Security and Privacy: Applications of cryptography
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

Resource-constrained devices such as wireless sensors and Internet of Things (IoT) devices have become ubiquitous in our digital ecosystem. These devices generate and handle a major part of our digital data. However, due to the impending threat of quantum computers on our existing public-key cryptographic schemes and the limited resources available on IoT devices, it is important to design lightweight post-quantum cryptographic (PQC) schemes suitable for these devices. In this work, we explored the design space of learning with error-based PQC schemes to design a lightweight key-encapsulation mechanism (KEM) suitable for resource-constrained devices. We have done a scrupulous and extensive analysis and evaluation of different design elements, such as polynomial size, field modulus structure, reduction algorithm, and secret and error distribution of an LWE-based KEM. Our explorations led to the proposal of a lightweight PQC-KEM, Rudraksh, without compromising security. Our scheme provides security against chosen ciphertext attacks (CCA) with more than 100 bits of Core-SVP post-quantum security and belongs to the NIST-level-I security category (provide security at least as much as AES-128). We have also shown how ASCON can be used for lightweight pseudo-random number generation and hash function in the lattice-based KEMs instead of the widely used Keccak for lightweight design. Our FPGA results show that Rudraksh currently requires the least area among the PQC KEMs of similar security. Our implementation of Rudraksh provides a $sim3 imes$ improvement in terms of the area requirement compared to the state-of-the-art area-optimized implementation of Kyber, can operate at $63%$-$76%$ higher frequency with respect to high-throughput Kyber, and improves time-area-product $sim2 imes$ compared to the state-of-the-art compact implementation of Kyber published in HPEC 2022.

Problem

• Post-Quantum Cryptography
• Lightweight Algorithms
• IoT Security

Innovation

• Post-Quantum Cryptography
• Lightweight KEM
• FPGA Optimization