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Talk of quantum computers no longer sounds like science fiction at crypto events. At a recent developer gathering, the ETH Denver, engineers and security researchers turned their attention to a simple but unsettling question: what happens to Bitcoin if a powerful quantum machine comes online?
Reports have disclosed that new proposals are being folded into the network’s improvement process, laying early groundwork for defenses before any real crisis appears.
Hashing — what miners and many parts of the system use — gets faster only a bit with quantum tricks. According to Lov Grover’s work, a quantum search method gives a square-root speedup, which changes safety margins but does not wipe them out.
In plain language: to break hashes at scale would need enormous, maybe unrealistic, machines under current models.
Reports say the bigger worry is signatures. “What we’re worried about in the next five years are signatures, and that goes over with Shor’s,” Hunter Beast, co-author of BIP 360, said during the ETH Denver gathering.
The math behind most wallets today relies on elliptic curves, and Peter Shor showed a way a quantum machine could reverse that math.
That’s how a public key could reveal a private key once the right hardware exists. A blockchain security firm has been tracking addresses that have already exposed their public keys, and the numbers are not tiny.
Blockchain cybersecurity firm Project Eleven’s list flags millions of coins that, if an attacker had a big enough quantum device, would be at risk.
Estimates have been moving. Older papers put the needed resources in the many millions of qubits. More recent research from groups like Iceberg Quantum suggests the figure could be much lower, perhaps into the six-figure range.
Still, raw qubit counts tell only part of the story. What matters is how many “logical” qubits you can run with acceptable error rates, how long calculations take, and whether the machine can stay stable for that time.
Lab steps by big firms also matter; for example, Google has reported progress in error correction that many found encouraging. That doesn’t mean the break-in is imminent, but it does change risk models.
Reports note teams are forming to study and build defenses. The Ethereum Foundation has a post-quantum group, and major exchanges and firms are taking part in discussions.
Coinbase set up advisers, and its CEO, Brian Armstrong, has said the problem can be handled with planning. It is “solvable”, he said.
