To date, the threat of a quantum computer to Bitcoin no longer seems as fantastic as it was some time ago.
Quantum technologies are developing rapidly and the emergence of a quantum computer that can hack the bitcoin blockchain based on ECDSA P-256 is just around the corner.
The problem is not even that a quantum computer can hack bitcoin. The problem is that a quantum computer of sufficient power will be able to crack any classical crypto-protection at all, including any quantum-unsecured blockchain.
Although Bitcoin is the most popular cryptocurrency with the largest capitalization, it is just one cryptocurrency. To date, there are more than 20 thousand cryptocurrencies on the cryptocurrency market and 99.9% of them do not have protection against a quantum computer attack.
The development of quantum technologies in recent years
Dr. Mark Webber from the University of Sussex said that in order to crack the protection of bitcoin, you need a quantum computer with a capacity of at least 13 million physical qubits (analogue of bits in classical computers). It will take 24 hours for such a quantum computer to crack the Bitcoin ECDSA P-256 elliptic curve. At the time of the interview, Dr. Webber said that the best quantum computers have a power of 50-100 physical qubits.
On the other hand, IBM promises to create a quantum computer with a capacity of 1000 physical qubits by 2023.
And in January 2022, the appearance of the first quantum computer in Europe (in Germany) with a capacity of 5000 qubits was announced.
Technologies do not stand still, and today no one can say exactly when a quantum computer of sufficient power will appear to crack 99.9% of all classical cryptography that exists today, including the cryptography of most of the blockchains that exist today. And the question is not even whether this is possible or not, but the whole question is only when exactly this will happen?
The US government and government agencies are already preparing for the transition to post-quantum cryptography
The American government already at the end of 2018 issued a document called “NATIONAL QUANTUM INITIATIVE ACT”
This law, in fact, aims to promote quantum technologies and US dominance in the world arena in the field of quantum technologies.
Following this, the US government agency NIST released a white paper in April 2021 called “Getting Ready for Post-Quantum Cryptography” about the quantum computer threat to most classical cryptography methods.
In 2022, NIST has identified four candidate algorithms for standardization. NIST will recommend two primary algorithms to be implemented for most use cases: CRYSTALS-KYBER (key-establishment) and CRYSTALS-Dilithium (digital signatures). In addition, the signature schemes FALCON and SPHINCS will also be standardized.
Does quantum secure blockchains even exist?
Yes. In 2018, the first quantum-secured QRL blockchain was launched.
This QRL project is secured by XMSS (eXtended Merkle Signature Scheme), a National Institute of Standards and Technology (NIST)-approved post-quantum secure digital signature scheme.
The capitalization of the QRL project is about $13M at the time of writing.
The Future of Quantum Technologies
No one can say with an accuracy of up to a year when a quantum computer with sufficient power will appear to crack most of the cryptography methods that exist today.
It is only clear that we are not talking about a decade, but about the next few years.
It is also clear that it is unlikely that any scientific researcher in their right mind would want to hack the bitcoin blockchain or any other blockchain.
The point is not that someone will seriously engage in hacking blockchains, the point is the very possibility of this hack.
That is why all parties interested in the security of their projects should take care of the transition to post-quantum protection today.