Paper 2025/1871
A Unified Approach to Quantum Key Leasing with a Classical Lessor
Abstract
Secure key leasing allows a cryptographic key to be leased as a quantum state in such a way that the key can later be revoked in a verifiable manner. In this work, we propose a modular framework for constructing secure key leasing with a classical-lessor, where the lessor is entirely classical and, in particular, the quantum secret key can be both leased and revoked using only classical communication. Based on this framework, we obtain classical-lessor secure key leasing schemes for public-key encryption (PKE), pseudorandom function (PRF), and digital signature. We adopt the strong security notion known as security against verification key revealing attacks (VRA security) proposed by Kitagawa et al. (Eurocrypt 2025) into the classical-lessor setting, and we prove that all three of our schemes satisfy this notion under the learning with errors assumption. Our PKE scheme improves upon the previous construction by Goyal et al. (Eurocrypt 2025), and our PRF and digital signature schemes are respectively the first PRF and digital signature with classical-lessor secure key leasing property.
Metadata
- Available format(s)
-
PDF
- Category
- Foundations
- Publication info
- A major revision of an IACR publication in CRYPTO 2026
- Keywords
- QuantumSecure key leasing
- Contact author(s)
-
fuyuki kitagawa @ ntt com
jiahuiliu crypto @ gmail com
yamada-shota @ aist go jp
takashi yamakawa @ ntt com - History
- 2026-07-21: last of 2 revisions
- 2025-10-08: received
- See all versions
- Short URL
- https://ia.cr/2025/1871
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2025/1871,
author = {Fuyuki Kitagawa and Jiahui Liu and Shota Yamada and Takashi Yamakawa},
title = {A Unified Approach to Quantum Key Leasing with a Classical Lessor},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/1871},
year = {2025},
url = {https://eprint.iacr.org/2025/1871}
}
