Overview
The second quantum revolution will lift quantum technologies to a new level. The developed applications will not only use quantum-mechanical effects present in nature, but actively engineer them. The most prominent example of modern quantum technologies is certainly the quantum computer, which will enable computational tasks that were previously infeasible. However, researchers in quantum information also investigate for which other tasks quantum mechanics can bring an advantage. They have already found a variety of further applications: more efficient communication lines, extremely precise clocks and sensors as well as new cryptographic methods.
Quantum devices to distribute a secure key (and securely encrypt messages) can be implemented using ‘standard’ optical components such as lasers, optical fiber and photon detectors. This quantum technology can therefore already be realized and used in practice. The question however remains, whether there are other tasks from quantum cryptography and communication that can equally be implemented with ‘standard’ photonic components and which could therefore be realized today? Recently, Çakan, Goyal, Liu-Zhang and Ribeiro [CGLZR23] have proposed to use quantum mechanics to solve the cryptographic problem of secret sharing: how can a secret be shared among several people, such that it can only be reconstructed by all of these people together? This functionality can e.g. ensure that a group of people can only access a safe together. Secret sharing is furthermore a crucial building block in more complicated cryptographic tasks such as electronic voting. The proposed quantum secret-sharing protocol — contrary to previous “classical” (i.e. non-quantum) version — has the advantage that it is leakage resilient. Even if an attacker manages to obtain any amount of (classical) information about the shares, they cannot reconstruct the secret. This protocol therefore constitutes a further example of tasks which are enabled by quantum technology, but would be impossible without it. This very recent proposal is promising, but currently only a theoretical suggestion.
This project will render the new cryptographic application of leakage-resilient quantum secret practical, prepare an experiment and collaborate with an experimental group to show the new protocol. We will develop the theoretical description of the protocol to be implementable by ‘standard’ optical components similar to quantum key distribution; we will design an experiment taking into account the specific tools available in the laboratory of the University of Vigo; we will support the experimental group for the actual implementation and we will describe our results in a scientific paper. These results will therefore give another application of quantum technology in cryptography which is realizable with present-day technology.
