Applied Algebra Group at the University of Zürich


The impact of quantum computers to blockchain based systems and possible countermeasures

Andreas Bolfing's talk
Date: 12.12.18   Time: 16.00 - 17.00   Room: Y27H12

Many online applications, especially in the financial industries, are running on blockchain technologies in a decentralized manner, without the use of an authoritative entity or a trusted third party. Such systems run in a permissionless environment, using a decentralized consensus mechanism in order to achieve integrity in purely distributed peer-to-peer systems. The blockchain is a public append-only ledger that forms an eventual consistent system, which relies on cryptographic primitives, such as hash functions and digital signatures. However, these cryptographic primitives are vulnerable in the presence of quantum computers, which makes the whole system potentially unsafe. We give a detailed introduction to decentralized technologies which rely on blockchain based systems, based on the example of Bitcoin, and to its cryptographic parts. We analyze the possible impact if any cryptographic primitive in the protocol is broken. Finally, we give an outline of post-quantum cryptography approaches which should assure the security of the blockchain in the era of quantum computers.