Systematic Study of Decryption and Re-encryption Leakage: The Case of Kyber

Azouaoui, Melissa; Bronchain, Olivier; Hoffmann, Clément; Kuzovkova, Yulia; Schneider, Tobias; Standaert, François‐Xavier

doi:10.1007/978-3-030-99766-3_11

Cited by 4 publications

(2 citation statements)

References 28 publications

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“…More recently, Azouaoui considered the case of Kyber as an example of Simple Power Analysis (SPA) against the re-encryption of schemes using the FO transformation and the Differential Power Analysis (DPA) against the decryption, with shortcut formulas in order to compare their strengths in function of the noise level [17]. They evaluated the cost of preventing them with masking and later discuss tweaks to improve the situation and enable a better leveling of the countermeasures.…”

Section: Side-channel Attacksmentioning

confidence: 99%

“…The motivation of this proposal comes from the fact that several publications (v.gr. [10,13,16,17]) present attacks against the re-encryption part of the FO ⊥ transformation applied to Kyber. As explained in [17], the re-encryption process consists in running the PKE, which in the case of Kyber is only IND-CPA, so an IND-CCA adversary may have a significant advantage against the scheme.…”

Section: Transformation Without Re-encryptionmentioning

confidence: 99%

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Analysis of the FO Transformation in the Lattice-Based Post-Quantum Algorithms

2022

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Newer variants of the Fujisaki–Okamoto transformation are used in most candidates of the third round of the NIST Post-Quantum Cryptography standardization call in the category of public key encryption schemes. These transformations are applied to obtain a highly secure key encapsulation mechanism from a less secure public key encryption scheme. Furthermore, there are five candidates (three finalists and two alternatives) that passed to the third round of the process and whose security is based in lattice problems. This work analyzes the different ways in which the lattice-based candidates of the NIST call apply the Fujisaki–Okamoto transformation and the particularities of each application. The study of such differences and their repercussion in the design of the proposals will allow a better understanding of the algorithms. Moreover, we propose a modification of the Kyber algorithm—the only public key encryption candidate established as a PQC standard by NIST in its more recent publication—in order to avoid the re-encryption in the decapsulation algorithm and, in this way, to reduce the side channel attacks vulnerability.

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Section: Side-channel Attacksmentioning

confidence: 99%