A new report from Google is putting a spotlight on something the crypto space has talked about for years, but never really had to confront head-on: the impact of quantum computing on blockchain security.
In its latest findings, Google Quantum AI estimates that about 6.9 million Bitcoin could one day be exposed to quantum attacks. That’s not an immediate risk, but it’s big enough to start raising serious questions about long-term security.
🚨 Google has sounded the quantum alarm 🚨
Today, they released groundbreaking progress towards breaking crypto using a quantum computer.
TLDR – Existing cryptography is dead. Mempool attacks are real. We must migrate to post-quantum now.
Thread 🧵 pic.twitter.com/PQoS72kJfp
— Project Eleven (@projecteleven) March 31, 2026
For now, nothing changes for users. But the report makes it clear that this isn’t just a far-off theory anymore, it’s something developers and institutions may need to start planning for.
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Old Bitcoin Wallets Pose The Biggest Risk
Not all Bitcoin is equally exposed. The report points to around 1.7 million BTC sitting in older wallet formats known as Pay-to-Public-Key (P2PK). These were used in Bitcoin’s early days, when transactions revealed public keys directly on-chain.
That design choice now creates a problem. Those public keys are permanently visible, which means a future quantum attacker wouldn’t need to wait for any new activity, they already have the data they need.
Some of these coins are believed to belong to Satoshi Nakamoto, Bitcoin’s mysterious creator. They’ve remained untouched for years, becoming part of crypto lore. But in a quantum scenario, their inactivity could actually make them easier targets.
It’s a strange twist, what once represented security through dormancy could eventually turn into a vulnerability.
A Future Attack Could Happen Silently
One of the more unsettling takeaways from the paper is how quietly these attacks could happen.
Unlike traditional crypto hacks, which usually involve phishing or compromised exchanges, a quantum attack wouldn’t need any visible trigger. If a public key is already exposed, an attacker could theoretically derive the private key directly, no transaction required.
That means funds could be accessed without warning. No suspicious movement beforehand, no signal for the owner to react.
Researchers estimate that a powerful enough quantum machine could calculate a Bitcoin private key in about nine minutes. That’s just under the network’s average 10-minute block time, which makes the idea feel less abstract and more technically plausible, just not yet achievable.
A Multibillion-Dollar Target Emerges
The scale of what’s at stake is hard to ignore. The report describes these vulnerable coins as a “fixed, multibillion-dollar target,” sitting out in the open on the blockchain.
They can’t be hidden or moved without exposing more data. They’re simply there, visible to anyone, including future attackers.
Because of that, the paper floats an unusual idea: governments may need to step in at some point. One suggestion is a framework for “digital salvage,” where long-dormant, vulnerable coins could be treated like abandoned treasure.
The thinking is to prevent bad actors from getting there first. It’s a controversial concept, but it shows just how seriously researchers are taking the issue.
Ethereum Faces Faster And Broader Exposure
While Bitcoin’s risk is mostly tied to older wallets, Ethereum could face a broader challenge.
According to the same research, a sufficiently advanced quantum computer could potentially compromise Ethereum’s top 1,000 wallets in under nine days. Together, those accounts hold around 20.5 million ETH.
The difference comes down to design. On Ethereum, a user’s public key becomes visible as soon as they make their first transaction, and it stays exposed permanently.
That means a much larger share of the network could be at risk in a quantum future, not just early adopters or inactive wallets.
Smart Contracts And Network Security At Risk
The concerns don’t stop at individual wallets. The report also points to deeper vulnerabilities within Ethereum’s system.
One major issue is smart contract admin keys. These control massive amounts of value, including over $200 billion in stablecoins and tokenized assets. If those keys were ever compromised, the fallout could spread quickly across the ecosystem.
There’s also the question of Ethereum’s Proof-of-Stake system, which relies on BLS signatures. These aren’t designed to withstand quantum attacks, meaning a powerful enough system could interfere with how the network confirms transactions.
In other words, the risk isn’t just about stolen funds, it could affect the integrity of the blockchain itself.
A Race Toward Quantum-Resistant Solutions
There is, at least, some progress on the horizon. The Ethereum Foundation is already exploring post-quantum cryptography, looking for ways to upgrade the network before the threat becomes real.
That early start could make a difference. Transitioning to quantum-resistant systems won’t be easy, but planning ahead gives Ethereum a better shot at handling it smoothly.
Bitcoin may have a tougher path. Its slower, more conservative approach to upgrades has helped it stay stable over the years, but it could also make rapid changes more difficult if the need arises.
For now, both networks remain safe. Quantum computers capable of pulling this off don’t exist yet. But the direction is clear, and the gap between theory and reality may not stay as wide as it once seemed.
Disclosure: This is not trading or investment advice. Always do your research before buying any cryptocurrency or investing in any services.
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