The adaptations that cryptocurrencies would have to undergo to fend off quantum attacks would decrease their usability.
These are the results of a study conducted by Stephen Homes, Arqit’s chief product officer, and Liqun Chen from the University of Surrey. In the paper, the authors posit that quantum computers could in theory use Shor’s algorithm to break cryptocurrencies’ encryption. They believe this algorithm could break Elliptic Curve Digital Signature Algorithm (ECDSA) signatures, which many cryptocurrencies depend on.
Increased defense, decreased usability
Keeping on top of the threat posed by quantum computers requires a significant change in user behavior, the paper continues. However, the authors also emphasized that cryptocurrencies would become increasingly less usable with each additional protection measure.
To make security user-friendly, cryptocurrencies would have to migrate to quantum safe digital signature schemes. However, doing so would require a hard fork. This is a much more complex process, involving high levels of community consensus to ensure successful implementation.
Another alternative highlighted by the authors would be to migrate a cryptocurrency to a new platform designed specifically to be quantum resistant. “This could be achieved relatively easily through an exchange process as a cryptocurrency is becoming more at risk to the ever-increasing performance of quantum computers,” the authors note.
Quantum computers’ cap
Conversely, many cryptocurrency developers and experts still remain skeptical. Some believe there’s no indication that quantum computing will ever be strong enough to break either the necessary encryption.
A quantum computer, in contrast to a traditional one, operates not with bits or bytes (one unit of information in a double system of calculation) but with quantum bits, or qubits. This technology speeds up computer processing hundreds of times. The hardware is also more complex than that of its predecessors. There are more parts than a traditional computer, and it must be super cooled constantly.
Former quantum physicist now involved in the crypto space, Stepan Snigirev, also attests it is unlikely that quantum computers will become a threat to cryptocurrencies in the next 20 years. According to his calculations, it would optimistically take three to five years to achieve an order of magnitude improvement in qubits and their processing power. To achieve a level necessary to break elliptic curve cryptography would therefore roughly take 15 to 20 years.