Our questions were answered by Dmitry Kotov, a WEB3 visionary, the founder and CEO of CryptoConsulting company, an expert in decentralized technologies and information security.
Quantum computers are to replace regular ones — Google is intended to launch commercial production by 2029. Some representatives of the crypto community see this trend as a danger to the blockchain - huge computing power can become a threat to the security of private keys and transactions. Whether this is the case, how the advent of quantum computers can affect the blockchain is our topic.
A quantum computer summary
While an ordinary computer has familiar transistors that either pass current or not (taking one of two states: 0 or 1), quantum computer’s qubit (a standard bit counterpart) can be the heads and the tails at the same time and a quantum superposition state is also valid (being in all 3 states simultaneously). Whereas a standard computer calculates with variations of bits, a quantum computer immediately “sees” all the solutions — because a set of qubits makes up the entire set of combinations at once. Thus, it performs calculations much faster.
About "much faster": in September 2019, the "Quantum Supremacy Using a Programmable Superconducting Processor" report appeared on behalf of Google — it was published on the NASA website. The report said: in 200 seconds Google's quantum computer performed a calculation that would take the most powerful Summit supercomputer about 10 thousand years. This was a moment of “quantum superiority” — when a problem that could not be solved by ordinary computers was solved by a quantum one.
Current developments
According to Google's latest promises, the release of commercial quantum computers is planned by 2029. Billions of dollars are being invested in the development — even a separate Google Quantum AI campus in California has been built. Engineers from IBM are competing with Google — they introduced the IBM Quantum System One in 2021 — a quantum computer with a capacity of 27 qubits. Intel is moving from the development of classical processors to quantum ones — as you can see, the giants of the industry are actively working with quantum computing.
What's wrong with quantum computing and the blockchain?
The blockchain is based on cryptographic algorithms that prevent errors in the network and transactions, hacking. Thanks to such algorithms, the blockchain is considered safe and protected from hacking.
But all this is true if we are talking about standard computing power. Quantum computers perform calculations instantly: and if you now pick a private key (which is a 32-byte number consisting of 64 characters), then with quantum computing the task is quite feasible.
Vulnerability of digital signatures
Deloitte experts spoke about the security threat from quantum computers in their study. Specifically, they talk about the vulnerability of transactional digital signatures — according to analytics, 21% of all BTC mined may be vulnerable.
There are two types of Bitcoin addresses: P2PK (Pay-to-Public-Key) and P2PKH (Pay-to-Public-Key Hash). It was believed that with the power of a quantum computer, only a P2PK address could be opened by calculating the private key from the public one. The thing is: the hacker got to get the public key, if you do not disclose it and do not spend coins (and also do not use the same address twice), then the address is safe.
In P2PKH addresses, a digital signature is created on the basis of a private key, and it was believed that this provides protection against being picked using quantum capacities. However, experts say that if one address is used twice, a quantum computer could hack it as well.
Can a quantum computer change data in transactions?
No, because several participants of the network are involved in confirming the transaction. In this case, no amount of computing power would help altering the transaction, since the consensus algorithm wouldn’t be bypassed.
How about we mine coins on a quantum computer?
If a quantum computer is so fast and powerful, it's tempting to think how fast coins can be mined on it. However, there is no need to worry that someone will get all the bitcoins quickly: mining coins would simply be ineffective due to the use of the SHA-256 hashing algorithm. ASIC-i will manage mining much better.
The bigger danger
In fact, the danger of quantum powers is much broader than the blockchain. Imagine how many modern systems are protected by encryption — and are considered secure, they are really impossible to crack with the power of an ordinary computer. But what if we try to open them with the help of a quantum computer? They will be defenseless.
Financial systems, secret government data — everything, absolutely everything can end up in the wrong hands if the right capacities are available. That is why there is a stir around the development of quantum computers at the state level now — no one wants to be “cracked open” quicker than the protection of the new order will appear.
How to secure the blockchain from quantum computers
The problem of quantum computers can be called potential, but not yet real. At least, nothing threatens the crypto world in the coming years: quantum computers remain in laboratories for the time being, and are unlikely to be available to private individuals.
Dmitry Kotov notes that encryption algorithms and security methods in the blockchain aren’t standing still also — there is always a way to prevent a potential threat. With the known progress in quantum computing, there is time to develop methods of counteraction.
What can secure the blockchain from quantum computers:
- A more complex encryption algorithm (for example, SHA-512)
- Larger private key size
- Transition to post-quantum cryptography
The US National Institute of Standards and Technology (NIST) is conducting research on encryption algorithms that will be resistant to quantum computing. Private projects are also working on this task, including IOTA, ArQit, Quantum Resistant Ledger, HyperCash, Starkware or Uranium-X. Developments in the field will definitely receive large state subsidies.
In conclusion:
Crypto Consulting believes that a sudden “takeover” of the blockchain by quantum computers will definitely not happen — so far that’s only a theoretically possible assumption. Blockchain will gradually become quantum-stable, and this will happen before the incredible power of quantum computers becomes publicly available.