Future quantum computers could crack the private keys that guard cryptocurrency wallets, Europol said in a report published Wednesday. For Bitcoin wallets whose public keys are already visible, the EU police agency says no cryptographic fix exists.
Europol rejects claims that quantum computing will collapse crypto. Its warning is narrower, and falls on individual holders rather than the network.
Why Europol Says Wallets, Not the Blockchain, Are the Weak Point
Every Bitcoin (BTC) wallet runs on a pair of linked codes. Anyone can see the public key, while the private key authorizes spending.
A powerful enough quantum computer could work backward from the public key to the private one, letting an attacker move the funds, Europol’s cybercrime unit said.
The hashing math that chains Bitcoin’s blocks together is far harder to break, the report finds.
For coins with public keys, the report offers one way out.
“Once a public key is exposed, it remains permanently vulnerable to future quantum decryption.”
Owners must move those funds to new wallets before any attack arrives, Europol says.
How Many Bitcoin Are Already Exposed, and How Long Would a Rescue Take?
Analytics firm Glassnode put the figure at 6.04 million BTC in May, or 30.2% of all coins issued. At Bitcoin’s current price near $83,050, that stash is worth roughly $502 billion.
Most of it is exposed through reused addresses and exchange wallets, Glassnode found. The rest sits in older script formats, including Satoshi Nakamoto’s early coins.
Whether a holder’s coins sit in that group depends on how they are stored, according to Glassnode.
Most standard Bitcoin addresses show only a scrambled fingerprint of the public key, keeping the key itself hidden. Those coins are not counted as exposed.
That changes once the owner sends a payment from the address. The transaction reveals the key, and any coins left behind at that address lose their cover, Glassnode said.
Coins held on exchanges often land in the exposed group, because platforms tend to reuse addresses. Taproot addresses, a format added in 2021, and Bitcoin’s earliest addresses show the key by default.
Quantum-safe signatures are 10 to 120 times larger than today’s, Europol notes, which could clog blocks and raise fees.
One study the report cites estimates a full migration would need at least 76 days of the network’s entire capacity. Spreading it across a quarter of each block stretches that to about 300 days.
A second Europol report warns attackers could store encrypted data now and unlock it once quantum machines exist. It found no clear evidence of this at scale.
Europol set no date for such machines. It argues that upgrades on a network with no central operator take years, and some developers already back plans to freeze vulnerable coins.
