PKE and ABE with Collusion-Resistant Secure Key Leasing

Fuyuki Kitagawa; Ryo Nishimaki; Nikhil Pappu

Paper 2025/262

PKE and ABE with Collusion-Resistant Secure Key Leasing

Fuyuki Kitagawa, NTT Social Informatics Laboratories, Tokyo, Japan, NTT Research Center for Theoretical Quantum Information, Atsugi, Japan

Ryo Nishimaki

, NTT Social Informatics Laboratories, Tokyo, Japan, NTT Research Center for Theoretical Quantum Information, Atsugi, Japan

Nikhil Pappu

, Portland State University

Abstract

Secure key leasing (SKL) is an advanced encryption functionality that allows a secret key holder to generate a quantum decryption key and securely lease it to a user. Once the user returns the quantum decryption key (or provides a classical certificate confirming its deletion), they lose their decryption capability. Previous works on public key encryption with SKL (PKE-SKL) have only considered the single-key security model, where the adversary receives at most one quantum decryption key. However, this model does not accurately reflect real-world applications of PKE-SKL. To address this limitation, we introduce collusion-resistant security for PKE-SKL (denoted as PKE-CR-SKL). In this model, the adversary can adaptively obtain multiple quantum decryption keys and access a verification oracle which validates the correctness of queried quantum decryption keys. Importantly, the size of the public key and ciphertexts must remain independent of the total number of generated quantum decryption keys. We present the following constructions: - A PKE-CR-SKL scheme based on the learning with errors (LWE) assumption. - An attribute-based encryption scheme with collusion-resistant SKL (ABE-CR-SKL), also based on the LWE assumption. - An ABE-CR-SKL scheme with classical certificates, relying on multi-input ABE with polynomial arity.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Preprint.
Keywords: Quantum Cryptography Secure Key Leasing Key Revocation
Contact author(s): fuyuki kitagawa @ ntt com
ryo nishimaki @ ntt com
nikpappu @ pdx edu
History: 2025-02-23: revised; 2025-02-18: received; See all versions
Short URL: https://ia.cr/2025/262
License: CC BY

BibTeX

@misc{cryptoeprint:2025/262,
      author = {Fuyuki Kitagawa and Ryo Nishimaki and Nikhil Pappu},
      title = {{PKE} and {ABE} with Collusion-Resistant Secure Key Leasing},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/262},
      year = {2025},
      url = {https://eprint.iacr.org/2025/262}
}