The blockchain technology that powers cryptocurrencies faces a significant challenge from the rise of quantum computing. Do quantum computers pose a real threat to the blockchain? Can they break encryptions that protect cryptocurrencies that are considered secure? We explain!

Blockchain vs quantum computers 

Blockchain, on which hugely popular cryptocurrencies are based, is considered a fully secure network that a hacking attack cannot breach. However, there is no shortage of opinions that this may change with the spread of quantum computers. One of the most well-known applications of quantum computers is overcoming the mathematical difficulty underlying most current cryptography. The powerful calculating machines can process information about 100 trillion times faster than a traditional computer.

Quantum computers use the effects of quantum physics to reduce the time required to solve computational problems by creating and exploiting so-called quantum superpositions. Although quantum computing is still in its early stages, it is being watched closely by the blockchain and cryptocurrency community. To understand why, let’s briefly discuss what quantum computing is characterized by.

Quantum computing – what does it consist of?

The key difference between quantum computers and traditional devices is how they process information. Classical computers use chunks of data called “bits” to store information in one of two states: zeros and ones. Each of these zeros and ones represents electrical signals of high or low voltage, which the computer interprets into what is seen on the device’s screen. Quantum computers store information in quantum bits – qubits, taking on what is known as superposition, in which “0” and “1” occur at the same time. 

Qubits’ high level of complexity gives quantum computers the potential to process data many times faster than classical computers. Thus, it allows them to solve computational problems faced by classical computers. It is possible to achieve incomparably higher efficiency of many processes thanks to quantum computers. Although it sounds extremely promising, devices of this type are only at the initial stage of development. Enthusiasts of the topic point to the possible use of quantum computing in research on artificial intelligence, work on new materials and medicines or supply chain optimization in many industries.

How will quantum computing affect the crypto world?

The possibilities that quantum computing brings with it have raised some concerns, especially in cryptocurrencies. According to some experts, quantum computing threatens the viability of blockchain technology due to the latter’s use of asymmetric cryptography, also known as public-key cryptography. In asymmetric cryptography, private and public keys are generated in pairs. The private key is kept secret, while the public key is made available to the public. 

In blockchain technology, the public keys are used as wallet addresses, and the private keys are used to access the funds in the cryptocurrency wallet. In classical computing, the public wallet address can be obtained from the wallet’s private key. However, it does not work the other way – private keys cannot be obtained from public addresses. The proliferation of quantum computers may make it feasible to determine the private keys associated with any public wallet address on the blockchain. This, in turn, implies a real threat to existing blockchains.

The performance of quantum computers themselves could also be potentially dangerous. The foundation of blockchain and cryptocurrency-based security is power. The more computers that make up a blockchain, the better protected that network is from hacking attacks. To break into this decentralized network, huge computing power would be needed. Future quantum computers are supposed to be characterized by it.

Do quantum computers threaten blockchain and cryptocurrencies?

To sum up – currently available quantum computers cannot threaten blockchain. Sufficiently powerful devices can change this state with high performance. Using the public key declared by the sender of the transaction, quantum computers can decrypt private keys, commonly used in cryptocurrencies. In particular, transactions waiting to be added to the blockchain will be vulnerable to attacks.

However, the cryptocurrency market can be expected to meet them by creating technologies to address possible threats. In particular, the dangers of quantum attacks may be offset by post-quantum cryptography algorithms already being developed.

Quantum technology may prove to be a bigger problem for other, traditional systems based on classical cryptography. These, in contrast to the blockchain, may not be able to cope with an update making them immune to the capabilities of quantum computers.