163252 20251024172258.0 doi 10.1007/s12095-025-00837-z sideral 145720 ART-2025-145720 eng Hernández Costoya, Alba CCA-attacks on lattice-based encryption-decryption schemes 2025 This paper presents two distinct chosen-ciphertext attacks (CCA) against lattice-based encryption and decryption schemes, in particular based on the LWE problem, a class of post-quantum cryptographic algorithms. First we attack fully homomorphic encryption-decryption schemes (FHE) exploiting the additional information that the small modulus reduction offers. We compare this attack with the CPAD attack presented in Checri (2024). Afterwards we present an attack against Kyber.CPAPKE, and another against a weakened version of Kyber.KEM where the cyphertext is not checked for correctness; and compare them to the previous Key Mismatch Attack in Qin (2021). Our work remarks the importance of protecting the decryption function in the different implementations of these cryptographic schemes, and the importance of CCA security in nowadays cryptosystems. Access copy available to the general public Unrestricted info:eu-repo/grantAgreement/ES/DGA/E22-23R info:eu-repo/grantAgreement/ES/MICINN/CEX2021-001142-S-20–9 info:eu-repo/grantAgreement/ES/MICINN/PID2020-114750GB-C31/AEI/10.13039/501100011033 info:eu-repo/semantics/openAccess by https://creativecommons.org/licenses/by/4.0/deed.es info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Larraya Sancho, Alba Marco Buzunáriz, Miguel Ángel Universidad de Zaragoza (orcid)0000-0002-6750-8971 2006 440 Universidad de Zaragoza Dpto. Matemáticas Área Geometría y Topología (2025), [16 pp.] Cryptogr. commun. Cryptography and communications 1936-2447 2776676 http://zaguan.unizar.es/record/163252/files/texto_completo.pdf Versión publicada 1132415 http://zaguan.unizar.es/record/163252/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:163252 articulos driver 2025-10-24-16:55:48 ARTICLE