Welcome to the resource topic for 2025/1197
Title:
How to Copy-Protect All Puncturable Functionalities Without Conjectures: A Unified Solution to Quantum Protection
Authors: Alper Çakan, Vipul Goyal
Abstract:Quantum copy-protection (Aaronson, CCC’09) is the problem of encoding a functionality/key into a quantum state to achieve an anti-piracy security notion that guarantees that the key cannot be split into two keys that both still work. Most works so far has focused on constructing copy-protection for specific functionalities. The only exceptions are the work of Aaronson, Liu, Liu, Zhandry, Zhang (CRYPTO’21) and Ananth and Behera (CRYPTO’24). The former constructs copy-protection for all functionalities in the classical oracle model and the latter constructs copy-protection for all circuits that can be punctured at a uniformly random point with negligible security, assuming a new unproven conjecture about simultaneous extraction from entangled quantum adversaries, on top of assuming subexponentially-secure indistinguishability obfuscation (iO) and hardness of Learning with Errors (LWE).
In this work, we show that the construction of Aaronson et al (CRYPTO’21), when the oracles are instantiated with iO, satisfies copy-protection security in the plain model for all cryptographically puncturable functionalities (instead of only puncturable circuits) with arbitrary success threshold (e.g. we get CPA-style security rather than unpredictability for encryption schemes), without any unproven conjectures, assuming only subexponentially secure iO and one-way functions (we do not assume LWE). Thus, our work resolves the five-year-old open question of Aaronson et al, and further, our work encompasses/supersedes and significantly improves upon all existing plain-model copy-protection results.
Since puncturability has a long history of being studied in cryptography, our result immediately allows us to obtain copy-protection schemes for a large set of advanced functionalities for which no previous copy-protection scheme existed. Further, even for any functionality F that has not already been considered, through our result, constructing copy-protection for F essentially becomes a classical cryptographer’s problem.
Going further, we show that our scheme also satisfies secure leasing (Ananth and La Placa, EUROCRYPT’21), unbounded/LOCC leakage-resilience and intrusion-detection security (Cakan, Goyal, Liu-Zhang, Ribeiro, TCC’24), giving a unified solution to the problem of quantum protection.
ePrint: https://eprint.iacr.org/2025/1197
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