Quantum Security and Cryptography: You Are (Probably) Doing it Wrong presented at BlackHatEurope 2020

by Tommaso Gagliardoni,

Summary : Quantum Cryptography is not just Alice and Bob exchanging qubits: There is a whole world of exotic applications that use quantum effects for securing information and that are just impossible to achieve with traditional cryptography. But why should we care given that most of these applications are still at a far research stage?In this talk, we will face an uncomfortable fact about quantum computing (QC) and cryptography: all the recent attention brought to quantum-resistant cryptography (fueled by the advancement in QC research and the NIST standardization process) leads only to a short-term security solution once QC becomes available. The reason: quantum-resistant cryptography (often dubbed "post-quantum") can only protect classical digital (binary) information. But given the very peculiar characteristics of quantum information (such as the impossibility of copying data and the destructive action of observation), new encryption systems able to cope with quantum data and quantum networks have to be designed with a completely different approach, and show surprising behaviors. Not to be confused with currently existing "quantum key distribution" (QKD), which is a very specific and limited branch of it, quantum cryptography is designed to be run natively on a QC device proper, and able to act on quantum data.In this talk (that does not assume expertise in quantum mechanics) we will dive into quantum cryptography and we will see:How many classical cryptographic tasks (one-time pad, block ciphers, public-key encryption, etc.) have a quantum counterpart;How some other ones are very hard to translate quantumly (e.g., authentication) or simply impossible (digital signatures);How quantum cryptography enables new functionalities that have no counterpart in traditional cryptography: unclonable keys, offline money, quantum lightning, one-time programs, and much more!