Generic Composition: From Classical to Quantum Security

Nathalie Lang; Jannis Leuther; Stefan Lucks

Paper 2025/387

Generic Composition: From Classical to Quantum Security

Nathalie Lang

, Bauhaus University, Weimar

Jannis Leuther

, Bauhaus University, Weimar

Stefan Lucks

, Bauhaus University, Weimar

Abstract

Authenticated encryption (AE) provides both authenticity and privacy. Starting with Bellare's and Namprempre's work in 2000, the Encrypt-then-MAC composition of an encryption scheme for privacy and a MAC for authenticity has become a well-studied and common approach. This work investigates the security of the Encrypt-then-MAC composition in a quantum setting which means that adversarial queries as well as the responses to those queries may be in superposition. We demonstrate that the Encrypt-then-MAC composition of a chosen-plaintext (IND-qCPA) secure symmetric encryption scheme SE and a plus-one unforgeable MAC fails to achieve chosen-ciphertext (IND-qCCA) security. On the other hand, we show that it suffices to choose a quantum pseudorandom function (qPRF) as the MAC. Namely, the Encrypt-then-MAC composition of SE and a qPRF is IND-qCCA secure. The same holds for the Encrypt-and-MAC composition of SE and a qPRF

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Preprint.
Keywords: Post-Quantum Authenticated Encryption Generic Composition
Contact author(s): nathalie lang @ uni-weimar de
jannis leuther @ uni-weimar de
stefan lucks @ uni-weimar de
History: 2025-03-04: approved; 2025-02-28: received; See all versions
Short URL: https://ia.cr/2025/387
License: CC BY

BibTeX

@misc{cryptoeprint:2025/387,
      author = {Nathalie Lang and Jannis Leuther and Stefan Lucks},
      title = {Generic Composition: From Classical to Quantum Security},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/387},
      year = {2025},
      url = {https://eprint.iacr.org/2025/387}
}