Experts Downplay Quantum Threat to Cryptocurrencies

Private keys in the Bitcoin network are unlikely to be cracked by quantum computers in the near future, according to Cointelegraph, citing expert opinions.

In October, news emerged of the “world’s first effective attack” on the Present, Gift-64, and Rectangle algorithms using a quantum computer. These represent a SPN structure, which underpins the AES encryption standard, employed in military and financial sectors.

The breakthrough poses a “real and significant threat” to the long-used password protection mechanism in critical sectors, researchers claim.

Details of the breach remain unclear, but if confirmed, it would mark a “step forward” in the evolution of quantum computing, according to physicist Marek Narozniak, who has experience in the field.

Based on available data, it is difficult to assess the vulnerability of password protection mechanisms used across various industries, including cryptocurrencies, noted Massimiano Sala, professor and head of the cryptography lab at the University of Trento.

Much depends on whether scientists have managed to crack RSA keys of a certain size, such as those used by banks. There is no evidence of this, the expert said.

The D-Wave computers used by Chinese scientists can only perform specialized tasks. If universal quantum computers emerge in the future, they could threaten the entire elliptic curve cryptographic structure protecting Bitcoin.

In the future, quantum computers might be able to derive a private key in the network of the first cryptocurrency unless countermeasures are developed.

“However, we must remember that D-Wave are not general-purpose quantum computers,” noted Sala.

Takaya Miyano, a professor of mechanical engineering at Ritsumeikan University in Japan, pointed out that the integer factored by Shanghai researchers was 22 bits long. This is much shorter than actual RSA integers, which are typically 1024 bits or more, such as 2048 and 4096.

“The D-Wave machine is a kind of quantum simulator for solving optimization problems, not a universal computer,” he added.

Factorization

Factorization is the mathematical process of breaking down a number or algebraic expression into factors. In other words, it is finding numbers that multiply to give the original expression. For example, 12 can be factored into 2 × 2 × 3.

Effective factorization of prime numbers is the “Holy Grail” for cracking the RSA public-key cryptosystem, experts noted.

The main principle of this encryption is that multiplying two prime numbers is easy, but finding these numbers, knowing their product, is very difficult. As the numbers increase, the complexity grows.

Previously, Sala’s colleagues at the University of Trento used quantum annealing to identify the two prime factors of the number 8,219,999 — 32,749 and 251. He noted that the recent work by Shanghai University is significant “only if researchers have found a way to factorize large numbers.”

Cryptocurrency Keys Remain Secure

Suppose Chinese scientists have indeed found a way to use quantum annealing to crack cryptographic algorithms like SPN, which is fundamental to AES.

“Symmetric ciphers like AES-128, used for data encryption, are not vulnerable to such attacks because they do not rely on number factorization,” noted Narozniak.

He added that there may be exceptions, for example, if the cipher is a shared secret obtained through an RSA-based key exchange protocol. But “properly encrypted passwords and other data will remain intact, even if the approach presented in this study is scaled and becomes widely available.”

Narozniak emphasized that hasty conclusions should not be drawn, and optimism should not be overestimated. It is worth waiting until someone can replicate the results of the Chinese scientists.

This Is Not the First Quantum Breach

The expert noted that at the beginning of 2023, it was reported that researchers in China succeeded in factoring a 48-bit key on a 10-qubit quantum computer.

“This has not yet passed peer review. Two years prior, the respected Klaus Schnorr claimed that RSA had been cracked. I personally take such bold statements with a grain of skepticism,” commented Narozniak.

Sala pointed out that if such an encryption algorithm is cracked, many programs would need updating, but no radical changes would be required. Standards already exist that provide alternatives, such as elliptic curve cryptography (ECC), used to protect Bitcoin.

Buterin’s Idea — A Hard Fork

In March, Ethereum co-founder Vitalik Buterin highlighted that the second-largest cryptocurrency by market capitalization already has good potential to protect users’ funds from quantum computers through a simple “recovery fork.”

“The blockchain would require a hard fork. Users would need new wallet software, but few would lose their funds,” he stated.

Narozniak noted that such a hard fork would not be “simple.” Multiverse Computing’s CTO Samuel Mugel shares this view.

“A hard fork would be complex, require broad consensus, and could not restore all lost assets or full trust in the network. To avoid such a situation, it is crucial to integrate quantum-resistant cryptography before an attack occurs,” he noted.

Security Measures Needed

Christos Makridis, a research assistant professor at Arizona State University, noted that “we need to reassess our current cybersecurity measures.” In the world of quantum computing, more attention should be paid to network load, i.e., protection against distributed denial-of-service attacks, and passwords.

“One new perspective is that the development of quantum computing and generative AI has made it possible to advance more quickly than defense,” he observed.

Sala urged the blockchain world to prepare as soon as possible because “dangerous quantum computers will emerge, it’s only a matter of time.” A roadmap for transitioning to post-quantum cryptography and developing security measures capable of withstanding attacks is needed.

Previously, Lawrence White, a professor of economics at George Mason University, stated that in the distant future, the security of the first cryptocurrency is threatened not by quantum computing, but by changes in the reward model for miners.

Vitalik Buterin believes that account abstraction could make user accounts quantum-resistant.

For more on how existing quantum computers work and whether fears about them are justified, read on ForkLog.