What 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-backed Laboratories are racing to close that gapBut the clock ticks. NIST, the US National Institute of Standards and Technology has started to approve post-quantum algorithm while many public blockchains are still using encryption from the 1980s.

It’s still a hypothetical threat. 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 hack

Bitcoin’s security is based on Elliptic Curve Digital Signature Algorithm (ECDSA), a cryptographic algorithm first introduced in 1985. Users can prove ownership by using a private-key, but only the public-key is visible on the network.

A sufficiently powerful quantum computing device could recover the private key from a publicly exposed one using Shor’s algorithms. It would be possible for attackers access wallets where the public keys are exposed. This includes early Bitcoin wallets.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.”

In this scenario, blockchain transactions would be processed as usual. 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. Although ECDSA is far from the capabilities of traditional computing, it can be used with Bitcoins’ 256-bit key.

Bitcoins is the main reason behind TradFi’s post-quantum encryption

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

“All the blockchains have identified this vulnerability as a root cause,” Dhiman referred to the possibility that quantum computers could break current encryption techniques like ECDSA.

To transition Bitcoin from a traditional model to one that is quantum resistant, the consensus rules of the network would need to be rewritten. This requires a large amount of coordination between miners and developers.

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

Early proposals have been floated by researchers, such as Bitcoin Improvement Proposal 360The document outlines possible pathways to adopting new cryptographic systems, as well as the “Post Quantum Migration and Legacy Signatures Sunset” Proposal to phase out existing signature schemes. Ethereum developers also investigated lattice-based signatures There are other options that can resist quantum, but none has been implemented.

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.”

Some of the newer projects in blockchain are already positioning themselves for quantum readiness. In an independent proposal, Carvalho’s Naoris protocol was mentioned. submitted Dhiman’s Quranium, on the other hand, uses NIST-approved Stateless Hash-Based Digital Signature Algorithm. Quantum Resistant Ledger uses XMSS, a NIST-standard algorithm for hash-based digital signatures.

What will happen if Bitcoin fails to pass the quantum test?

The primary concern for the average Bitcoin owner is the sudden loss of confidence that could cause prices to plummet and spread through the traditional markets where the adoption of cryptocurrency by institutions has been increasing.

“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,” “Enigma” he said, in reference to the Enigma code.

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. To prevent Germany’s use of the cipher, the Allies kept their breakthrough secret.

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

Experts remain confident that a quantum-secured blockchain system is 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.”

For the time being, quantum threats are only theoretical. Bitcoin is encrypted and it’s hard to break. Computer that can do so only exist on paper.

Magazine: Bitcoin vs. the quantum computer threat: Timeline and solutions (2025–2035)