000163252 001__ 163252 000163252 005__ 20251024172258.0 000163252 0247_ $$2doi$$a10.1007/s12095-025-00837-z 000163252 0248_ $$2sideral$$a145720 000163252 037__ $$aART-2025-145720 000163252 041__ $$aeng 000163252 100__ $$aHernández Costoya, Alba 000163252 245__ $$aCCA-attacks on lattice-based encryption-decryption schemes 000163252 260__ $$c2025 000163252 5060_ $$aAccess copy available to the general public$$fUnrestricted 000163252 5203_ $$aThis 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. 000163252 536__ $$9info:eu-repo/grantAgreement/ES/DGA/E22-23R$$9info:eu-repo/grantAgreement/ES/MICINN/CEX2021-001142-S-20–9$$9info:eu-repo/grantAgreement/ES/MICINN/PID2020-114750GB-C31/AEI/10.13039/501100011033 000163252 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es 000163252 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000163252 700__ $$aLarraya Sancho, Alba 000163252 700__ $$0(orcid)0000-0002-6750-8971$$aMarco Buzunáriz, Miguel Ángel$$uUniversidad de Zaragoza 000163252 7102_ $$12006$$2440$$aUniversidad de Zaragoza$$bDpto. Matemáticas$$cÁrea Geometría y Topología 000163252 773__ $$g(2025), [16 pp.]$$pCryptogr. commun.$$tCryptography and communications$$x1936-2447 000163252 8564_ $$s2776676$$uhttps://zaguan.unizar.es/record/163252/files/texto_completo.pdf$$yVersión publicada 000163252 8564_ $$s1132415$$uhttps://zaguan.unizar.es/record/163252/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000163252 909CO $$ooai:zaguan.unizar.es:163252$$particulos$$pdriver 000163252 951__ $$a2025-10-24-16:55:48 000163252 980__ $$aARTICLE