Quantum computers and Bitcoin: how will new technologies affect the security of the first cryptocurrency network?

Bitcoin uses public-key cryptography based on the Elliptic Curve Disorder Scaling Algorithm (ECDSA) for transaction signatures and the SHA-256 hash function for mining and address generation. ECDSA is also widely used in SSL/TLS certificates, device authentication, and other cryptographic protocols.

Quantum computers could, in theory, threaten public-key cryptography — including ECDSA — because they can efficiently solve discrete logarithm problems, which allows private keys to be cracked. In other words, a supercomputer that is too powerful could, in theory, crack the encryption and extract private keys from the public keys, thereby gaining control over any address it wants. This would make the networks that underpin digital assets insecure and make popular coins worthless. This is why coin lovers fear news of powerful devices.

However, hash-based algorithms like SHA-256 are still considered resistant to quantum attacks. Moreover, to protect the Bitcoin network in the future, post-quantum cryptographic schemes can be implemented, which will secure this blockchain.

Blockstream co-founder and CEO Adam Back has taken to Twitter to address the issue. He calls on the industry to prepare for what he calls the “post-quantum” (PQ) era – a new era in Bitcoin’s development where the cryptocurrency will have to withstand the threat of being “hacked” by quantum computing.

What Will Happen to Bitcoin and Cryptocurrencies Due to Quantum Supercomputers

Adam Back believes that the development of quantum computing technologies will help strengthen the security of the Bitcoin network. The post-quantum (PQ) period is “still at least a few decades away,” so a hash-based scheme for post-quantum signatures will never be viable, Back believes. Here is his comment on the matter.

Research into post-quantum signatures will eventually lead to conservative, well-studied, and more compact signatures, with Bitcoin being able to add these schemes as another option.

Bitcoin signatures prevent third parties from altering transactions and are an important part of the network’s security mechanism. When a transaction is made, private keys are used to sign the transfer as mathematical proof that the coins belong to the owner of the specified address.

According to sources at Cointelegraph , concerns about quantum computing’s ability to disrupt crypto transactions have been reignited by news of Google’s latest quantum computing chip. The chip, called Willow, solves a massive computational problem in under five minutes, while the most advanced supercomputers would take about 10 septillion years to complete the same task.

Willow is capable of exponentially correcting errors and performing certain calculations at mind-blowing speeds, said Hartmut Neven, head of Google’s Quantum AI division.

This supports the idea that quantum computing occurs in multiple parallel universes. This is consistent with the idea that we live in a multiverse, a prediction first made by David Deutsch.

Entrepreneur and former Google senior product manager Kevin Rose said Willow is far from a threat to cryptocurrencies. According to Rose, breaking Bitcoin’s encryption would require a quantum computer with about 13 million qubits to decrypt it in 24 hours.

By comparison, Google’s Willow chip, while a significant achievement, contains only 105 qubits.

Ethereum creator Vitalik Buterin is also preparing for the post-quantum era. Buterin has already proposed a way to reduce the risk of quantum computing for the Ethereum network with a simple hard fork that could eliminate the problem.

Google’s Willow launch was commented on by Ledger CTO Charles Guillaume. Here’s a quote from Twitter that will help you better understand the basics of blockchain — and at the same time stop worrying about the possibility of such networks being “hacked.”

Has Google created a quantum computer that breaks blockchain security? The short answer is no. Despite the impressive research results, we are still far from breaking modern cryptography.

There are three main categories of algorithms in cryptography:
1) Hashes: one-way functions that ensure data integrity. Blockchain security relies heavily on them.
2) Encryptions: functions that ensure privacy. Most blockchains rarely use them.
3) Signatures: functions that ensure authentication and non-repudiation. They are critical for proof of coin ownership and block validation in PoS systems. These primitives are based on asymmetric cryptography, which is also used for encryption and key agreement.

If hash functions or digital signatures were compromised, it would compromise the security of blockchains and much of our digital infrastructure.

According to Guillaume, such risks to cryptography have been known for a long time. Therefore, developers have already included conditions to minimize the danger.

Quantum computing has been exploring quantum algorithms since long before actual quantum computers were built. Two key algorithms are worth noting:

1) Grover’s Algorithm (1996): Speeds up searching for a specific element in an unsorted list, working quadratically faster than classical algorithms. Instead of sequentially checking elements, it checks many at once – it’s practically magic!
2) Shor’s Algorithm (1994): Efficiently factors large numbers and solves the discrete logarithm problem, which poses a threat to RSA encryption and elliptic curve cryptosystems.

From theory we know that:

1) Hash functions and symmetric encryption: These methods remain largely resistant to quantum computing. In the worst case, slightly longer keys or hashes will be required, but such solutions are already standardized.
2) Digital signatures: These are vulnerable. If a practical quantum computer is built, it will be able to break popular signatures like RSA, ECDSA, and Schnorr.

Charles also touched on the topic of the efficiency of quantum computers. He continues.

Building a quantum computer that can break cryptography is an incredibly difficult task. Despite significant investment, progress remains incremental due to significant engineering and scientific hurdles, especially as the number of qubits increases. The two main challenges are:

1) Preservation of quantum coherence and entanglement: qubits are extremely sensitive and easily lose their quantum state.
2) Error correction: scaling error correction as the number of qubits increases remains a huge challenge.

Google recently announced progress on the error correction problem. They managed to improve the error correction performance as the number of qubits increased. This result was achieved on their own benchmark called Random Circuit Sampling (RCS), which tests whether quantum computers actually exploit quantum effects. This includes performing calculations that are naturally suited to quantum processors, which classical computers can simulate very inefficiently. The announced speedup factor does not have full significance.

As a result, the Ledger representative comes to the following conclusion.

Despite its impressive achievements, this quantum computer has no practical applications yet. It is unlikely to be able to factor even small numbers, such as 42, any faster than classical computers, and working with larger numbers remains elusive.

Breaking asymmetric cryptography would require millions of qubits, as well as solving other problems such as scaling and converting classical problems to quantum systems.

Quantum computers, when released, will revolutionize computing and solve problems that were previously thought to be unsolvable. This could usher in a technological singularity—an era of unprecedented innovation. To witness such a transformation in my lifetime would be truly amazing.


The bottom line is clear: quantum computing does not currently pose a threat to the security of modern blockchains. And while that may change in the future, cryptocurrency developers will also be able to secure their networks. So it is definitely not worth writing off the technologies behind the coins just yet.


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