Blockchains in the Quantum Era

Digital Ledger Technologies (DLT) such as blockchain are being deployed as part of diverse applications that span multiple market segments. Application developers have successfully leveraged the blockchain characteristics of decentralization, immutability, cryptographic security and transparency to create the solution benefits of redundancy, non-repudiation and enhanced auditing/compliance. Blockchain infrastructures make very extensive use of digital signature algorithms, hashing algorithms and public-key cryptography. The rapid pace of progress that is being experienced with quantum computing technology has made the prospect of quantum computer cyber-attacks a very real possibility.

Initiatives are therefore underway to augment today’s DLT/blockchain infrastructures with cryptographic algorithms that are highly resistant to quantum computer attack. These post-quantum algorithms are based on computational problems that are known to be very difficult for quantum computers to solve by using either Shor’s algorithm or Grover’s algorithm. This paper provides an introduction to DLT/blockchain technology, some of its representative applications, and an overview of the leading post-quantum algorithm candidates that are actively being pursued.