Welcome to the resource topic for 2025/1842
Title:
Collusion-Resistant Quantum Secure Key Leasing Beyond Decryption
Authors: Fuyuki Kitagawa, Ryo Nishimaki, Nikhil Pappu
Abstract:Secure key leasing (SKL) enables the holder of a secret key for a
cryptographic function to temporarily lease the key using quantum
information. Later, the recipient can produce a deletion
certificate—a proof that they no longer have access to the secret
key. The security guarantee ensures that even a malicious
recipient cannot continue to evaluate the function, after producing
a valid deletion certificate.
Most prior work considers an adversarial recipient that obtains a single
leased key, which is insufficient for many applications. In
the more realistic collusion-resistant setting, security must
hold even when polynomially many keys are leased (and subsequently
deleted). However, achieving collusion-resistant SKL from standard
assumptions remains poorly understood, especially for
functionalities beyond decryption.
We improve upon this situation by introducing new pathways for
constructing collusion-resistant SKL. Our main contributions
are as follows:
-
A generalization of quantum-secure collusion-resistant traitor
tracing called multi-level traitor tracing (MLTT), and a compiler
that transforms an MLTT scheme for a primitive X into a
collusion-resistant SKL scheme for primitive X. -
The first bounded collusion-resistant SKL scheme for PRFs, assuming
LWE. -
A compiler that upgrades any single-key secure SKL scheme for
digital signatures into one with unbounded collusion-resistance,
assuming OWFs. -
A compiler that upgrades collusion-resistant SKL schemes with
classical certificates to ones having verification-query resilience,
assuming OWFs.
ePrint: https://eprint.iacr.org/2025/1842
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