Europol's European Cybercrime Centre (EC3) published two reports on October 7, 2026, concluding that quantum computing will not collapse cryptocurrencies — but that roughly 30% of Bitcoin's supply sits in addresses with exposed public keys that cannot be secured retroactively.

The EU police agency's cybercrime unit delivered its verdict on crypto's most-cited doomsday scenario in two documents, the primary one titled "Quantum Computing and Cryptocurrencies – Bridging Technical Expertise and Decision-Making." A companion report addresses the broader threat to encrypted data. Both build on Europol's earlier quantum technology assessments from 2023, now narrowed to digital assets.

The key finding was blunt: "Cryptocurrencies will not collapse due to quantum computing."

What does Europol actually say about the risk?

The report splits crypto security into two layers. The first is the blockchain itself — the vault. EC3 says network integrity holds because consensus relies on hash functions such as Bitcoin's SHA-256, which the agency describes as largely resistant to quantum attacks.

The second layer is the wallet infrastructure built on public-key cryptography. Europol calls wallets the "primary point of exposure."

The attack path is specific. A sufficiently capable quantum computer could work backward from an exposed public key, derive the matching private key, and then sign transactions the owner never approved. The concern is not the chain breaking; it is individual keys falling to a machine that can reverse today's signature schemes.

How big is the exposure?

The most striking figure in the report is the size of the vulnerable pool:

• Approximately 6 to 6.9 million BTC sit in addresses whose public keys have already been exposed.
• Europol pegs that at roughly 30% of Bitcoin's total supply.
• According to the agency, the only real protection is moving those funds to safe wallets before a capable quantum machine arrives.
• Exposed keys cannot be secured retroactively after the fact.

The agency recommends phased adoption of post-quantum cryptography, or PQC — encryption schemes designed to hold up against quantum computers — paired with wallet upgrades across the ecosystem.

Why can't Bitcoin just patch this?

Europol flags coordination as the central operational challenge. Bitcoin has no IT department that can push a mandatory update and force every participant to comply. Migration depends on dispersed users, custodians, wallet developers and miners acting in rough alignment without a central authority enforcing a deadline.

The scale of the technical task is measurable. The report estimates that migrating all Bitcoin unspent transaction outputs, known as UTXOs, could require more than 76 days of cumulative processing time under certain assumptions.

That timeline creates a strategic problem for holders. If a full migration could take over two months of processing and exposed keys cannot be protected after the fact, waiting until quantum machines are demonstrably capable would leave very little margin for error.

What does this mean for holders and builders?

For investors, the question shifts from whether the Bitcoin network survives quantum computing to whether a specific holder's coins sit in a vulnerable address. Under Europol's analysis, responsibility moves from the protocol to individual users: the remedy is proactive migration, not a network-level fix.

For wallet developers and custodians, the report signals a coming build cycle around PQC-compatible key generation and migration tooling, well before any cryptographically relevant quantum computer exists. The builders who ship those upgrades early will set the migration path everyone else follows.

The thorniest question involves coins whose owners never act. If roughly 30% of supply sits in exposed addresses, and protection depends on owners moving funds themselves, it is not obvious how every one of those coins gets secured. Dormant coins, lost keys and estates with no active manager may simply remain exposed — a permanent, unpatchable residue that Europol's framework leaves unresolved.

The practical takeaway from the EC3 analysis: the blockchain holds, the vault metaphor survives, but an estimated 6 to 6.9 million BTC now carry a risk that only decreases when owners move them. With migration timelines measured in months of cumulative processing, and post-quantum wallet upgrades still in phased adoption, the window for orderly migration — before quantum capability arrives on anyone's schedule — is the variable every large holder should now be modeling.