What would happen if quantum computers cracked Bitcoin today?

If a quantum computer capable of breaking modern encryption were to come online today, Bitcoin would likely be under attack — and no one would know.

“Everything would look like legitimate access,” David Carvalho is the CEO of Naoris Protocol a company that provides post-quantum technology infrastructure, he told Cointelegraph. “When you think you’re seeing a quantum computer out there, it’s already been in control for months.”

“You wouldn’t even know,” “He said”

IBM, Google Labs and Government-sponsored Laboratories are racing to close that gapBut the clock ticks. NIST (National Institute of Standards and Technology) in the US has approved post-quantum encryption algorithms. However, most public blockchains still use 1980s-era encryption.

This is a theoretical danger for now. Carvalho warns that, if Bitcoin defenses were to be a reality, they would fall faster than the system could respond.

Bitcoin could be broken by a quantum attack

Bitcoin’s fundamental security relies on Elliptic Curve Digital Signature Algorithm or ECDSA. This cryptographic standard was first proposed in the year 1985. It allows the user to verify ownership using their private key. Only the public key of the key can be seen by the rest of the network.

A quantum computer powerful enough to recover a secret key could do so by using Shor’s algorithm. This would enable attackers to gain access to any wallet that has the public key exposed, like those in early Bitcoin.BTC) transactions.

“It would be impossible to prove a quantum computer did it because it derives legitimate access,” Carvalho said. “You’d just see those coins move as if their owners decided to spend them.”

Related: Bitcoin’s quantum countdown has already begun, Naoris CEO says

Kapil Dhiman, CEO and founder of Quranium — a layer-1 blockchain startup focused on post-quantum security — warned that the earliest and most visible victims would be the oldest wallets.

“Satoshi’s coins would be sitting ducks,” Cointelegraph reported that he said this. “If those coins move, confidence in Bitcoin will shatter long before the system itself fails.”

The blockchain will continue to process transactions as normal in such a case. In this scenario, blocks are mined and the ledger remains intact. However, ownership has quietly been transferred.

Today, brute force attacks are slightly more effective due to the use of better algorithms and more powerful GPUs. Classical computing is still unable to handle ECDSA, even with Bitcoin’s keys of 256 bits.

Bitcoin and TradFi are behind post-quantum encryption

Although banks, government agencies, and telecom networks are testing the post-quantum technology, many major blockchains are still using technologies from the 1980s.

“All the blockchains have identified this vulnerability as a root cause,” Dhiman spoke of the danger that existing encryption methods such as ECDSA might be broken by quantum computer.

The network consensus rules would have to be overhauled, requiring broad cooperation among users, developers and miners.

Related: Lost your Bitcoin in California? You might get it all back

Researchers have made early suggestions, including Bitcoin Improvement Proposal 360This document describes possible ways to implement new cryptographic schemes and the “Post Quantum Migration and Legacy Signatures Sunset” Proposal to phase out existing signature schemes. Ethereum developers also investigated lattice-based signatures Other quantum-resistant alternatives exist, although none of them has reached the implementation stage.

A shift has already begun in the traditional financial sector. US NIST algorithms have been approved, and JPMorgan in partnership Toshiba has developed a quantum safe blockchain. SWIFT is now offering training on post-quantum safety for its network.

“Traditional finance is actually ahead,” Carvalho said. “They have central control, budgets and a single authority that can push upgrades. Crypto doesn’t have that. Everything takes a consensus.”

Several newer blockchains are aiming to be quantum-ready right from the start. Carvalho was the leader of Naoris, which is mentioned by an independent proposal submitted Dhiman’s Quranium is based on NIST-approved Stateless Hash-Based Digital Signature Algorithm. Quantum Resistant Ledger uses XMSS, a hash algorithm that is now standardized by NIST.

What if Bitcoin fails its quantum test

Bitcoin holders are most concerned about a sudden drop in confidence. This could lead to a price crash and cause ripples through markets that have been increasingly adopting cryptocurrencies.

“There is a non-zero probability of it being out now. The consensus in the scientific, research and military communities is that it is not the case,” Carvalho said.

“However, it would not be the first time world-class cryptography had been broken without public knowledge,” He added that he was referring to Enigma.

The Enigma code was used by Nazi Germany in World War II and it was thought to be unbreakable. The cipher was cracked by cryptanalysts at Bletchley, led by Alan Turing. They kept it secret to prevent Germany from continuing using the code.

“When you think you’re seeing a quantum computer, it’s already been in control for months,” Carvalho warned.

Experts remain confident that quantum-secure Blockchain systems will be achievable, and the industry has been trying to adopt standards that are already in place for traditional finance.

“Quantum-secure systems are possible,” Dhiman said “We just need to start building them before the threat becomes real.”

The quantum threat is still a theoretical one. Bitcoin’s cryptography is strong and only paper computers are capable of cracking it.

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