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

Quantum computers could, in theory, threaten public-key cryptography - and that includes ECDSA - because of their ability to efficiently solve discrete logarithm problems, allowing private keys to be cracked. In other words, in theory, an overly powerful supercomputer could break the encryption and extract private keys from publicly available public keys, thus gaining control of any desired address. Because of this, the networks at the core of digital assets would lose security and popular coins would lose their value. This is why coin enthusiasts dread the news of the emergence of productivity devices.

Blockchain developers

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

Blockstream co-founder and CEO Adam Back dedicated a fresh post on his Twitter page to this issue. He urges the industry to prepare for the so-called “post-quantum period” (PQ) – that is, a new era in the history of Bitcoin’s development, when the cryptocurrency will have to confront the danger of being “hacked” by quantum computing.

What will happen to Bitcoin and cryptocurrencies because of quantum supercomputers?

Adam Back believes that the development of quantum computing technologies will help to 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’s his comment on the matter.

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

Blockstream CEO Adam Back

Bitcoin’s 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.

Bitcoin BTC value changes over the week

According to Cointelegraph’s sources, concerns about quantum computing’s ability to disrupt crypto transactions have become relevant again due to news of Google’s latest quantum computing chip. This chip, called Willow, solves a large-scale computing problem in less than five minutes, whereas the most advanced supercomputers would take around 10 septillion years to complete the same task.

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Willow is capable of exponentially correcting errors and performing certain calculations at mind-boggling speeds, according to Hartmut Neven, head of Quantum AI at Google.

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

Kevin Rose, an entrepreneur and former senior product manager at Google, said Willow is far from a threat to cryptocurrencies just yet. According to Rose, breaking Bitcoin’s encryption would require a quantum computer with about 13 million qubits to perform the decryption in 24 hours.

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

Vitalik Buterin, the creator of Etherium, is also preparing for the post-quantum period. Buterin has already proposed a way to mitigate the risk of quantum computing to the Eth network with a simple hardfork that could eliminate the problem.

Etherium creator Vitalik Buterin

Google’s Willow launch was commented on by Ledger’s CTO Charles Guillaume. Here is his quote from Twitter, which will help you understand the basics of blockchain better – and at the same time stop worrying about the possible “hacking” of such networks.

Has Google created a quantum computer that breaks blockchain security? In a nutshell, no. Despite impressive research results, we are still far from breaking modern cryptography.

Generally speaking, there are three main categories of algorithms in cryptography:
1) Hashes: one-way functions that ensure data integrity. The security of blockchains largely depends on them.
2) Encryption: privacy-preserving functions. Most blockchains rarely use them.
3) Signatures: functions that guarantee authentication and non-repudiation. They are critical for proof of coin ownership and blockchain validation in PoS systems. These primitives are based on asymmetric cryptography, which is also used for encryption and key negotiation.

If hash functions or digital signatures were compromised, it would jeopardise blockchain security and much of our digital infrastructure.

Ledger’s chief technology officer Charles Guillaume

According to Guillaume, such risks to crypto have been known about for a long time. Therefore, developers have already put conditions in place to minimise the danger.

Quantum computing explores quantum algorithms long before real quantum computers. Two key algorithms deserve attention:

1) Grover’s (1996) algorithm: it speeds up the search for a particular item in an unsorted list, running quadratically faster than classical algorithms. Instead of sequentially enumerating elements, it checks many simultaneously – it’s practically magic!
2) Shor’s algorithm (1994): effectively factorises large numbers and solves the discrete logarithm problem, which is a threat to RSA encryption and elliptic curve based cryptosystems.

From theory, we know that:

1) Hash functions and symmetric encryption: these methods remain largely resistant to quantum computation. At worst, slightly longer keys or hashes will need to be used, but such solutions are already standardised.
2) Digital signatures: they are vulnerable. If a practical quantum computer is created, it will be able to crack popular signatures like RSA, ECDSA and Schnorr signatures.

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

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

1) Preserving 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 challenge. They have managed to improve error correction performance as the number of qubits increases. This result was achieved on their own benchmark called Random Circuit Sampling (RCS), which tests whether quantum computers actually use quantum effects. This involves performing calculations that are naturally suited to quantum processors, which classical computers can simulate extremely inefficiently. The announced acceleration factor is not fully relevant.

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In the end, the Ledger representative comes to the following conclusion.

Despite its impressive achievements, this quantum computer has no practical application yet. It is unlikely to be able to factorise even small numbers such as 42 faster than classical computers, and working with large numbers remains unattainable.

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

Quantum computers, once released, will revolutionise computing and enable solutions to problems previously thought intractable. This could be the beginning of a technological singularity – an era of unprecedented innovation. To witness such a transformation during my lifetime would be truly amazing.


The bottom line is clear: quantum computing does not yet threaten the security of today's blockchains. And while this may change in the future, cryptocurrency developers will also be able to secure their networks. So for now, it's definitely not a good idea to write off the technology behind the coins.


Look for more interesting things in our cryptocurrency chat. There we will talk about other important topics that influence the course of the current bullrun in the world of digital assets.

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