Can quantum computing break a Blockchain?

5 min read

While the virtues of the blockchain make it absolutely unbreakable with the current state of technology, it is true that the advance of quantum computing could threaten to break it.

Much has been discussed about this possible problem and although the theories are diverse, most agree that this will be an obstacle to which we must find a solution.

This should not frighten users in the crypto world since there are thousands of heads thinking of solutions to the advance of quantum. And as you know, if you inhabit this environment for a long time, the solutions appear incredibly fast.

What is quantum computing?

A quantum computer is a device that performs calculations based on the principles of quantum mechanics.

Normal computers use binary units (bits) that can represent two possible states (0 and 1) to store and manipulate information.

Quantum machines use Qubits, which unlike the previous ones, can be 0 and 1 at the same time. This allows them to execute many tasks in less time through this phenomenon known as “overlapping”.


Another primary concept in quantum theory is called “entanglement”. When two particles are intertwined, they come into existence in the same quantum state and the state is changed if one invites its pair to change accordingly (it does not matter if they are far apart in physical space).

This “pairing” of Qubits greatly enables the exponential growth of the computational power of a quantum machine.

The power is measured by considering the number of Qubits that a computer can harness simultaneously.

In the late 1990s, machines could reach two Qubits and today Google’s most powerful quantum computer can use up to 72 Qubits. An incredible advance.

Blockchain vs Quantum Computing

All the advances that physicists have been making over the last thirty years in pursuit of the creation of a quantum computer increases the danger to blockchain technology.

About a year ago, Google announced that it had achieved quantum supremacy, and although this was received with a lot of skepticism, it also caused a drop of about 10% in the price of Bitcoin.

This inevitably leads us to the question: Can a quantum computer like Google’s break a protocol like cryptos and help steal Bitcoins? How likely is this to happen in the near future?

Many quantum computing experts have spoken out on this, so we’ll let them do the talking.

For example, Yavi Altshuler, a researcher at MIT, said:

“While quantum computers are becoming more powerful and advancing much faster than people expected, their capabilities will not break the blockchain. There is no evidence that it can be compromised”.

Stewart Allen, director of quantum computing operations at IonQ, believes that when a quantum computer is powerful enough to compromise current blockchains, the security systems will have moved to algorithms capable of containing them.

“It is not real that there is a threat to blockchains because when quantum reaches the levels of danger that are spoken of, cryptography will also have advanced”.

On the other hand, Rakesh Ramachandran, CEO and co-founder of QBRICS Inc said:

“Quantum computers will redefine cryptography not only of the blockchain, but also wherever there is a cryptography application that includes simple things like an online banking website.  There is considerable research and work being done to mitigate the effects and move to quantum cryptography or post-quantum cryptography”.

“However, the challenge of the blockchain is not just the threat posed by quantum computing, but the scope of how the blockchain will migrate to the new version of cryptography”.


Most quantum experts agree that this danger could become present in a range of five to ten years. But they also agree that by that time formulas will be developed to avoid these quantum attacks.

The Blockchains will be forced to evolve and that will make quantum computing unlikely to threaten their existence. Quantum computing at the moment does not represent any real problem for the cryptography that protects cryptos.

However, it is worth mentioning that advanced cryptographic techniques resistant to quantum computation are already used in crypto-money such as Zcash or Monero. Bitcoin has also done part of this work, and continues to work on implementing Schnorr signatures and Confidential Transactions to its network natively.

In summary: We can be confident that all projects will continue to protect our money as they have been doing despite the evolution of quantum computing.