The blockchain is a distributed ledger platform with high Byzantine fault tolerance, which enables achieving consensus in a large decentralized network of parties who do not trust each other. A paramount feature of blockchains is the accountability and transparency of transactions, which makes it attractive for a variety of applications ranging from smart contracts and finance to manufacturing and healthcare. Blockchain relies on two one-way computational technologies: hash functions and digital signatures. Most blockchain platforms rely on the elliptic curve public-key cryptography or the integer factorization problem to generate a digital signature. The security of these algorithms is based on the assumption of computational complexity of certain mathematical problems. A universal quantum computer would enable efficient solving of these problems, thereby making digital signatures, including those used in blockchains, insecure. A way to guarantee authentication in the quantum era is to use quantum key distribution, which guarantees information-theoretic security based on the laws of quantum physics. Quantum key distribution is able to generate a secret key between two parties connected by a quantum channel (for transmitting quantum states) and a public classical channel (for post processing). We discuss a blockchain platform that is based on quantum key distribution and review possible experimental realizations for such a platform.

About the speaker: Dr. Aleksey Fedorov is the Junior Principal Investigator of the research group of Quantum Information Technologies at the Russian Quantum Center in Moscow, Russia. Aleksey studied Computer Science in Moscow, and obtained his PhD in Physics in Paris, in 2017. Currently he and his group studies the potential of quantum systems for information technology. Among other results, Aleksey's group has developed a protocol for a quantum-protected blockchain [Nature (London) 563, 465 (2018); Quantum Sci. Technol. 3, 035004 (2018)].