Cryptology ePrint Archive: Report 2018/838

(Tightly) QCCA-Secure Key-Encapsulation Mechanism in the Quantum Random Oracle Model

Keita Xagawa and Takashi Yamakawa

Abstract: This paper studies indistinguishability against quantum chosen-ciphertext attacks (IND-qCCA security) of key-encapsulation mechanisms (KEMs) in quantum random oracle model (QROM). We show that the SXY conversion proposed by Saito, Yamakawa, and Xagawa (EUROCRYPT 2018) and the HU conversion proposed by Jiang, Zhang, and Ma (PKC 2019) turn a weakly-secure deterministic public-key encryption scheme into an IND-qCCA-secure KEM scheme in the QROM. The proofs are very similar to those for the IND-CCA security in the QROM, easy to understand, and as tight as the original proofs.

Category / Keywords: public-key cryptography / Tight security, quantum chosen-ciphertext security, post-quantum cryptography, KEM

Original Publication (with minor differences): PQCrypto 2019

Date: received 5 Sep 2018, last revised 7 Feb 2019

Contact author: xagawa keita at lab ntt co jp

Available format(s): PDF | BibTeX Citation

Note: Correct errors on inaccurate keys and references. Add the proof for the HU conversion.

Version: 20190208:061017 (All versions of this report)

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