Vulnerability of blockchain technologies to quantum attacks

Joseph J Kearney,Carlos A Perez-Delgado

doi:10.1016/j.array.2021.100065

Abstract

Quantum computation represents a threat to many cryptographic protocols in operation today. It has been estimated that by 2035, there will exist a quantum computer capable of breaking the vital cryptographic scheme RSA2048. Blockchain technologies rely on cryptographic protocols for many of their essential sub-routines. Some of these protocols, but not all, are open to quantum attacks. Here we analyze the major blockchain-based cryptocurrencies deployed today -- including Bitcoin, Ethereum, Litecoin and ZCash, and determine their risk exposure to quantum attacks. We finish with a comparative analysis of the studied cryptocurrencies and their underlying blockchain technologies and their relative levels of vulnerability to quantum attacks.

Highlights

Blockchain systems are unlike other cryptosystems in that they are not just meant to protect an information asset
While from a classical perspective many of the small differences in the protocols have little impact on the overall security of the network, these differences can have a significant impact on how severe a quantum attack will be on the network, as we show in the subsequent sections
For each blockchain technology selected, we carefully studied the cryptographic primitives used, and their level of reliance on cryptographic protocols known to be vulnerable to quantum attacks

Summary

Introduction

Blockchain systems are unlike other cryptosystems in that they are not just meant to protect an information asset. Asymmetric encryption schemes such as RSA or Elliptic Curve (EC) cryptography are used to generate private/public key pairs that protect data assets stored on blockchains. The associated security relies on the difficulty of factoring, when using RSA, or of the discrete logarithm problem with EC. In a traditional banking system, public- and private-key cryptosystems are used to impose data confidentiality, integrity, and access rules. Revoking the key in a timely manner ensures the continued integrity and confidentiality of the data. The first class of algorithms is best represented by Shor’s algorithm[5] This algorithm can both factor large integers and solve the discrete logarithm in polynomial time. It can factor an integer N in time O log N log log N log log log N (or more succinctly O log N ) and space O (log N ).

Methods

Results

Conclusion