The quantum threat to Bitcoin resurfaces once every 18 months with the regularity of a Swiss train and the subtlety of a car alarm. I have been through enough of these cycles to set my watch by the pattern. A paper drops. The headlines write themselves. And within 48 hours, investors who have not thought about their cold wallet since the last scare are on the phone asking whether their holdings are safe.
I first heard the quantum argument in 2013, when I was mining Bitcoin on a farm I had built myself, barely four years after the network launched. The community was already discussing it then. Thirteen years later, the physics has advanced considerably. The panic has not changed at all.
What triggered this round was a paper from Google Quantum AI, published on March 30. It modelled an attack scenario which found that a quantum computer can derive a private key from an exposed public key in approximately nine minutes. Bitcoin’s average block confirmation takes ten. That gives an attacker a roughly 41 per cent chance of redirecting funds before the legitimate transaction confirms.
A separate paper from Caltech, published the same week, put the minimum viable attack even lower on a different architecture.
In reality, the gap between theoretically breakable and practically breakable remains enormous. What the papers established is that the gap is closing faster than assumed. That matters. It does not mean your wallet is in danger this quarter, or next year, or the year after that.
The wallets most at risk are not the ones you might expect. The nine-minute attack requires the public key to be visible, which only happens during the brief window between broadcasting a transaction and the network confirming it.
Coins sitting in cold storage, untouched, are among the safest. The genuinely exposed holdings belong to a different era. Early Bitcoin transactions between 2009 and 2012 used a format called Pay to Public Key, which embedded the public key permanently on the blockchain. Around 1.7 million Bitcoin sit in these addresses, including roughly 1.1 million attributed to Satoshi Nakamoto. Including other factors, the vulnerable supply reaches about 6.9 million coins. A third of everything in existence.
Which brings us to James Howells, the Welsh IT engineer who accidentally threw away a hard drive containing 8,000 Bitcoin in a Newport landfill in 2013. He has spent over a decade and at least one failed lawsuit trying to recover it. The High Court dismissed his case in January 2025 on the grounds that digging through 110,000 tonnes of compacted waste had no realistic prospect of success. In fairness to the judge, he had a point. But in 10 or 20 years, Mr Howells may not need the hard drive. His public key has been exposed on chain since the beginning. He may simply need to rent time on a quantum computer, derive his private key, and reclaim what is currently worth around £600 million ($791 million) without ever touching a shovel. It is the most expensive silver lining in the history of bad housekeeping.
Bitcoin’s developers are not ignoring the problem. BIP 360, the leading quantum resistance proposal, has been merged with the official repository and is running on testnet as of March 2026. The difficulty is not cryptographic theory but engineering cost.
Post quantum signatures are up to 80 times larger than what Bitcoin currently uses. A block that today holds around 7,600 transactions would hold fewer than 400 under the most robust replacement scheme. Convincing the Bitcoin community to accept that trade-off through a consensus process will take years.
Anyone who has watched commodity markets attempt co-ordinated supply adjustments will recognise the dynamic. Everyone agrees the problem is urgent. Nobody agrees on who absorbs the cost.
But here is the question that matters far more than the cryptography. Assume a sufficiently powerful quantum computer exists tomorrow. Who uses it? And on what?
Not Bitcoin. Not even close.
Intelligence agencies have been running what the security community calls "harvest now, decrypt later" operations for years. Diplomatic cables, military communications, defence contractor data, all collected today on the assumption that future quantum hardware will crack them open. It is the Enigma playbook. You do not announce you have broken the cipher. You read the enemy’s mail and keep your mouth shut. A cryptographically relevant quantum computer would be pointed at signals intelligence archives long before anyone thought about a blockchain.
Even within financial systems, the rational target is not theft. Breaking Bitcoin through a quantum attack is the Mona Lisa problem. The moment the first confirmed hack occurs, the market learns the encryption is broken. The price collapses before the attacker can exit. You cannot sell hundreds of billions of dollars in stolen coins into a market that has just discovered the coins are stealable. That is not a robbery. That is a bonfire.
The smarter play is asymmetric information: reading live SWIFT traffic, front-running institutional order flow, accessing merger communications before they go public. All of which extracts value without triggering a collapse and without revealing that the capability exists.
When you trade macro for long enough, you notice that the world, despite being vast, is remarkably small when it comes to narrative shaping.
The same pattern repeats across asset classes. A credible sounding paper arrives. The headlines amplify it. The enquiries follow. And the people who actually understand the mechanics sit patiently and explain, again, that the threat is real but the timeline is not what the headline suggests.
The quantum threat to Bitcoin will be solved, probably clumsily, probably late, and almost certainly after several more rounds of this exact panic cycle. The first casualties of quantum computing are already sitting on encrypted storage drives in government facilities, waiting for the machine that can read them. And James Howells may yet have the last laugh. Or at least the last shovel.
Yevgeny Bebnev is an investment professional and multi-manager fund specialist based in Dubai. He is also the founder and CIO of Alaris Capital
