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PQ.V.ALU.E: Post-quantum RISC-V Custom ALU Extensions on Dilithium and Kyber

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Smart Card Research and Advanced Applications (CARDIS 2023)

Part of the book series: Lecture Notes in Computer Science ((LNCS,volume 14530))

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This paper explores the challenges and potential solutions of implementing the recommended upcoming post-quantum cryptography standards (the CRYSTALS-Dilithium and CRYSTALS-Kyber algorithms) on resource constrained devices. The high computational cost of polynomial operations, fundamental to cryptography based on ideal lattices, presents significant challenges in an efficient implementation. This paper proposes a hardware/software co-design strategy using RISC-V extensions to optimize resource utilization and speed up the number-theoretic transformations (NTTs). The primary contributions include a lightweight custom arithmetic logic unit (ALU), integrated into a 4-stage pipeline 32-bit RISC-V processor. This ALU is tailored towards the NTT computations and supports modular arithmetic as well as NTT butterfly operations. Furthermore, an extension to the RISC-V instruction set is introduced, with ten new instructions accessing the custom ALU to perform the necessary operations. The new instructions reduce the cycle count of the Kyber and Dilithium NTTs by more than 80% compared to optimized assembly, while being more lightweight than other works that exist in the literature.

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  • 23 February 2024

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Correspondence to Konstantina Miteloudi .

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Miteloudi, K., Bos, J.W., Bronchain, O., Fay, B., Renes, J. (2024). PQ.V.ALU.E: Post-quantum RISC-V Custom ALU Extensions on Dilithium and Kyber. In: Bhasin, S., Roche, T. (eds) Smart Card Research and Advanced Applications. CARDIS 2023. Lecture Notes in Computer Science, vol 14530. Springer, Cham.

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