Quantum copy-protection of compute-and-compare programs in the quantum random oracle model [article]

Andrea Coladangelo, Christian Majenz, Alexander Poremba
2022 arXiv   pre-print
Copy-protection allows a software distributor to encode a program in such a way that it can be evaluated on any input, yet it cannot be "pirated" - a notion that is impossible to achieve in a classical setting. Aaronson (CCC 2009) initiated the formal study of quantum copy-protection schemes, and speculated that quantum cryptography could offer a solution to the problem thanks to the quantum no-cloning theorem. In this work, we introduce a quantum copy-protection scheme for a large class of
more » ... ive functions known as "compute-and-compare programs" - a more expressive generalization of point functions. A compute-and-compare program 𝖢𝖢[f,y] is specified by a function f and a string y within its range: on input x, 𝖢𝖢[f,y] outputs 1, if f(x) = y, and 0 otherwise. We prove that our scheme achieves non-trivial security against fully malicious adversaries in the quantum random oracle model (QROM), which makes it the first copy-protection scheme to enjoy any level of provable security in a standard cryptographic model. As a complementary result, we show that the same scheme fulfils a weaker notion of software protection, called "secure software leasing", introduced very recently by Ananth and La Placa (eprint 2020), with a standard security bound in the QROM, i.e. guaranteeing negligible adversarial advantage. Finally, as a third contribution, we elucidate the relationship between unclonable encryption and copy-protection for multi-bit output point functions.
arXiv:2009.13865v3 fatcat:xzf3rza7czfttapol2xcnspkga