International Joint Conference On Theoretical Computer Science – Frontier of Algorithmic Wisdom

August 15-19, 2022, City University of Hong Kong, Hong Kong


Invited Speakers

Female Forum

Quantum Copy Protection and Unclonable Cryptography

Jiahui Liu

PhD student at UT Austin

The unclonability of quantum information has been applied to quantum cryptography. In 1963, Wiesner put forward the pioneering idea of quantum money: banknotes encoded as quantum states that cannot be forged simply due to quantum mechanics. The idea was later used in the well-known BB84 quantum key distribution(QKD) protocol.
In this talk, I will present applications of unclonable quantum states beyond information-theoretic constructions such as Wiesner quantum money and QKD: we use and improve some past tools for quantum money and combine with techniques from classical cryptography to achieve more applications of computationally unclonable states.
One of these applications is quantum copy protection, first proposed by Aaronson in 2009: one can encode classical functional information into a quantum state so that this state can be used to evaluate a classical functionality but cannot be copied into two. Aaronson gave an open question on whether we can build a quantum copy protection scheme relative to a classical oracle.
I will then present a quantum copy protection scheme, using a classical oracle inspired by the 2012 Aaronson and Christiano's public key quantum money scheme. Furthermore, we can in fact replace the use of structured oracles with well-founded cryptographic primitives, when copy protecting specific functionalities that can lead to broad applicability.

Jiahui Liu is a fourth-year PhD student at UT Austin. Her main research interests are in the intersection of quantum information and cryptography, especially applications of quantum information in building cryptographic tools unrealizable by classical information. She is also interested in post-quantum security of cryptography and quantum information science in general.