Europol finds the quantum risk to crypto sits in exposed wallets, while blockchains hold up

In a report released Wednesday, Europol said that quantum computers will not be able to break blockchains. However, wallets whose public keys can be seen on the blockchain will need to move their money before an attack.

The European Cybercrime Center of the agency said that wallets were “the primary point of exposure to quantum threats.”

There are already public keys for about 6.04 million BTC

With a public key, the network checks that wallets have signed transactions. Wallets use a private key to sign transactions. The report says that if a quantum computer was strong enough, it could use an open public key to get the private key and spend the coins.

Hash functions that connect blocks and keep mining safe are still a lot harder to break. The report says that it would take about 2^128 quantum operations to break a 256-bit hash, which is “still astronomically high with foreseeable technology.”

The report comes to the conclusion that “cryptocurrencies will not collapse due to quantum computing.” It says, “Proactive adaptation, rather than systemic collapse, is the most likely outcome.”

There is no cryptographic fix for wallets that leave their public keys open. “The only solution is pre-emptive migration,” the report says, which means that owners move their money to new wallets that won’t be attacked first.

As of May, one on-chain count shows that 6.04 million BTC, or 30.2% of the supply, had their public keys made public. Another estimate puts the number closer to 6.9 million BTC. This number includes early pay-to-public-key outputs and Satoshi-era coins that haven’t been used in a long time.

There are already different opinions in the Bitcoin community about whether or not to freeze coins in wallets from the Satoshi era.

Bitcoin’s switch might need 76 days of downtime all together

Europol cites a study from 2024 that says it would take at least 76 days of total downtime to move all of Bitcoin’s unsigned transaction histories to a format that can’t be read by quantum computers. Putting 25% of each block on it would make the job take about 300 days longer.

Post-quantum signatures that are standardized by NIST are 10 to 120 times bigger than ECDSA signatures used by Bitcoin. The report says they might fill up block space, charge more, and make confirmations take longer.

A second report, called Harvest Now, Decrypt Later, was written with help from the University Carlos III of Madrid in Spain. It talks about attackers who store encrypted data today to crack it later. Europol hasn’t found any strong proof that this method is being used on a large scale.

The government said that high-value information that stayed secret for years would be the most likely target.

In September, Cryptopolitan said that the European Commission wants member states to start moving to systems that don’t use quantum computing by the end of 2026 and to move high-risk systems to systems that do use quantum computing before 2030.

The core post-quantum infrastructure for Ethereum is set to launch in 2029, and Bitcoin developers are looking into the BIP-360 soft fork.

Cryptopolitan said that in September, more than 100 researchers using AI coders were able to cut by 86.1% the number of resources needed for a single quantum attack on Bitcoin. The machine that can handle this kind of attack does not exist yet, and Europol did not say when it would.

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