Quantum computing has raised concerns about the future of cryptocurrency and blockchain technology in recent years. For example, it is widely believed that sophisticated quantum computers will one day be able to crack today’s encryption, making security a serious concern for users in the blockchain space.
The SHA-256 cryptographic protocol used for Bitcoin network security is currently unbreakable by today’s computers. However, experts believe that within a decade quantum computers will be able to break existing encryption protocols.
Regarding whether holders should worry about quantum computing posing a threat to cryptocurrency, Johann Polecsak, chief technology officer of the QAN platform, a Layer 1 blockchain platform, told Cointelegraph:
“Definitely. Elliptic curve signatures – which power all major blockchains today and are proven to be vulnerable to QC attacks – will break what is the ONLY authentication mechanism in the system. Once it breaks, it will be literally impossible to open a legitimate wallet -Distinguish owner from a hacker who forged a signature of it.”
If current cryptographic hashing algorithms are ever cracked, hundreds of billions worth of digital assets remain vulnerable to theft by malicious actors. Despite these concerns, however, quantum computing still has a long way to go before it becomes a viable threat to blockchain technology.
What is quantum computing?
Modern computers process information and perform calculations using “bits”. Unfortunately, these bits cannot exist in two places and in two different states at the same time.
Instead, conventional computer bits can have either the value 0 or 1. A good analogy is turning a light switch on or off. So, for example, if there is a pair of bits, those bits can only contain one of four possible combinations at any given time: 0-0, 0-1, 1-0, or 1-1.
From a more pragmatic point of view, this means that an average computer will probably take some time to perform complicated calculations, namely ones that have to consider every possible configuration.
Quantum computers do not have the same limitations as conventional computers. Instead, they use something called quantum bits, or “qubits,” instead of traditional bits. These qubits can coexist in states 0 and 1 at the same time.
As already mentioned, two bits can contain only one of four possible combinations at the same time. However, a single pair of qubits can store all four at the same time. And with each additional qubit, the number of possible options grows exponentially.
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As a result, quantum computers can perform many calculations while taking into account several different configurations. For example, consider the 54-qubit Sycamore processor developed by Google. It was able to complete a calculation in 200 seconds that would have taken the world’s most powerful supercomputer 10,000 years.
Simply put, quantum computers are much faster than traditional computers because they use qubits to perform multiple calculations at the same time. Also, because qubits can have a value of 0, 1, or both, they are much more efficient than the binary bit system used by current computers.
Different types of quantum computing attacks
In so-called memory attacks, a malicious party attempts to steal cash by targeting vulnerable blockchain addresses, e.g. B. those where the public key of the wallet is visible in a public ledger.
Four million bitcoin (BTC), or 25% of all BTC, are vulnerable to an attack by a quantum computer because the owners use unhashed public keys or reuse BTC addresses. The quantum computer would have to be powerful enough to decrypt the private key from the unhashed public address. If the private key is successfully decrypted, the malicious actor can steal a user’s funds right from their wallet.
However, experts estimate that the computing power required for these attacks would be millions of times greater than current quantum computers, which have fewer than 100 qubits. Still, researchers in the field of quantum computing have hypothesized that the number of qubits in use could reach 10 million in the next decade.
To protect against these attacks, crypto users must avoid reusing addresses or moving their funds to addresses where the public key has not been made public. This sounds good in theory, but can prove to be too tedious for everyday users.
Someone with access to a powerful quantum computer could attempt to steal money from a blockchain transaction in transit by launching a transit attack. Since this applies to all transactions, the scope of this attack is much larger. However, it is more difficult to execute because the attacker must complete it before the miners can execute the transaction.
In most cases, an attacker has no more than a few minutes due to the confirmation time on networks like Bitcoin and Ethereum. Hackers also need billions of qubits to perform such an attack, making the risk of a transit attack much lower than a memory attack. Nonetheless, users should still keep this in mind.
Protecting against assaults during transport is not an easy task. To do this, it is necessary to switch the underlying cryptographic signature algorithm of the blockchain to one that is resistant to a quantum attack.
Measures to protect against quantum computing
There is still a lot to do with quantum computing before it can be considered a credible threat to blockchain technology.
Additionally, blockchain technology will most likely evolve to address the issue of quantum security until quantum computing becomes widely available. There are already cryptocurrencies like IOTA that use Directed Acyclic Graph (DAG) technology, which is said to be quantum resistant. Unlike the blocks that make up a blockchain, directed acyclic graphs are made up of nodes and connections between them. Thus, the records of crypto transactions take the form of nodes. Then the records of these exchanges are stacked on top of each other.
Block lattice is another DAG-based technology that is quantum resistant. Blockchain networks like the QAN platform use the technology to enable developers to create quantum-resistant smart contracts, decentralized applications, and digital assets. Lattice cryptography is resistant to quantum computing because it relies on a problem that a quantum computer may not be able to easily solve. The name of this problem is the shortest vector problem (SVP). Mathematically, the SVP is a question of finding the shortest vector in a high-dimensional lattice.
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The SVP is believed to be difficult to solve for quantum computers due to the nature of quantum computing. Only when the states of the qubits are fully aligned can the superposition principle be used by a quantum computer. The quantum computer can use the superposition principle when the states of the qubits are perfectly matched. However, it must resort to more conventional calculation methods when the states are not. As a result, a quantum computer is very unlikely to be able to solve the SVP. Therefore, lattice-based encryption is secure against quantum computers.
Even traditional organizations have taken steps toward quantum security. JPMorgan and Toshiba have teamed up to develop Quantum Key Distribution (QKD), a solution they claim is quantum-resistant. Through the use of quantum physics and cryptography, QKD allows two parties to exchange sensitive data while simultaneously identifying and thwarting any attempt by a third party to eavesdrop on the transaction. The concept is seen as a potentially useful security mechanism against hypothetical blockchain attacks that quantum computers could perform in the future.