Freiburg 2019 – scientific programme

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FM: Fall Meeting

FM 31: Secure Communication & Computation II

FM 31.2: Talk

Tuesday, September 24, 2019, 14:30–14:45, 1009

Exploring the potential of device-independent quantum cryptography — •Gláucia Murta — Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany

Current secure communication is based on cryptographic methods whose security relies on computational assumptions. While this approach works well at the moment, if more powerful computers become available in the future, the content of encrypted messages exchanged today could be revealed (what is called retroactive attacks). Quantum key distribution (QKD) offers a solution to this problem because security is established directly from fundamental laws of physics. However, while unbreakable in principle, the security of QKD protocols relies on a very precise characterization of their physical implementation, which can be very hard to obtain in practice. In fact, this has led to hacking of several quantum cryptosystems. Surprisingly, quantum mechanics also offers a solution to this problem. In the so-called device-independent (DI) setting, security can be guaranteed even if the users are completely ignorant about the internal working of their devices. In this setting, security relies on the violation of a Bell inequality. So far, most of the proposed protocols are based on the CHSH inequality. Very little is known about the use of general Bell inequalities. A big challenge is that many theoretical tools used to deal with the CHSH inequality do not apply to Bell inequalities with more inputs and outputs. In order to get an insight on the potential of general Bell inequalities, we analyze the performance of different Bell inequalities for DIQKD under the assumption that the underlying system has a fixed dimension d.