Europol Warns Quantum Threat Targets Specific Bitcoin Wallets

A Friendly Look at Quantum Computing and Bitcoin Security

Quantum computers sound like something from a futuristic movie. They process information using advanced physics that traditional supercomputers cannot match.

Recently, European law enforcement agency Europol published a cybercrime report. The report looks at how future quantum machines might affect cryptocurrency security.

Europol made an important distinction right at the start. Quantum computers will not destroy or collapse the entire Bitcoin network.

Instead, the danger is much narrower. It targets specific individual wallets where public keys are already visible.

How Bitcoin Keys Work (And Where the Vulnerability Lies)

To understand the risk, let us look at how Bitcoin wallets function. Every wallet relies on a pair of linked cryptographic keys.

Think of your public key like a bank account number. Anyone can see it, and people use it to send you funds.

Your private key acts like your secret password. It gives you the sole authority to spend or transfer those funds.

Under current mathematical rules, calculating a private key from a public key is practically impossible. Traditional computers would take billions of years to guess it.

However, Europol's cybercrime unit noted that a powerful quantum computer could work backward. It could calculate your secret private key directly from your exposed public key.

Once an attacker calculates your private key, they can control and move your funds.

Importantly, the mathematical hashing that chains Bitcoin blocks together is far harder to break. The underlying blockchain logic remains secure.

Is Your Bitcoin Wallet Exposed?

Not every Bitcoin address is immediately vulnerable to quantum attacks. Most standard addresses do not display the actual public key publicly.

Instead, standard addresses display a hashed version of the public key. This acts like a scrambled fingerprint, keeping the true key hidden.

However, a public key becomes exposed to the public network under specific circumstances:

• Sending Bitcoin from an address reveals its public key to the entire network.
• Reusing the same address for multiple transactions leaves remaining funds exposed.
• Exchange wallets frequently reuse addresses for operational convenience.
• Taproot addresses, introduced in 2021, reveal the public key by default.
• Legacy script formats from Bitcoin's early days display public keys openly.

The legacy address category includes early coins mined by Bitcoin creator Satoshi Nakamoto.

By the Numbers: How Much Bitcoin Is at Risk?

Blockchain analytics firm Glassnode analyzed exposed addresses in May. They found that roughly 6.04 million BTCBTC-2.34% sit in exposed wallets.

That figure represents about 30.2% of all issued Bitcoin. At a price near $83,050 per BTC, that stash is worth roughly $502 billion.

Please remember that digital asset prices are subject to high market volatility. Short-term price movements can fluctuate significantly.

Past performance of digital assets is not a guarantee of future results. Learn more about current market trends at bitkub.com/th/market/BTC.

Glassnode confirmed that address reuse and exchange wallets account for the largest portion of exposed coins.

The Challenge of Migrating Vulnerable Funds

Europol emphasizes that no software patch can fix an already exposed public key. Once revealed, the key remains permanently vulnerable to quantum decryption.

The only fix for holders is to move funds to fresh, unexposed addresses before quantum machines exist.

However, migrating millions of coins across the network presents practical obstacles. Quantum-resistant cryptographic signatures are much larger than standard signatures.

Europol noted that quantum-safe signatures can be 10 to 120 times larger than current formats.

Larger signatures take up more block space, which could clog the network and drive transaction fees higher.

The report cites research estimating the timeline for a total network migration:

• Using 100% of network block capacity, a full migration would take at least 76 days.
• Using 25% of block capacity to avoid severe congestion stretches the timeline to roughly 300 days.

Understanding 'Harvest Now, Decrypt Later'

A second report from Europol highlights a strategy called Harvest Now, Decrypt Later.

In this scenario, bad actors record and store exposed encrypted data today. They hold onto this data until functional quantum computers become available.

Once quantum technology matures, attackers could decrypt the collected keys and access the funds.

Europol found no clear evidence that attackers are currently conducting this harvesting at scale.

Furthermore, law enforcement officials did not set a specific date for when quantum machines might arrive.

How the Bitcoin Community Is Preparing

Upgrading a decentralized network without a central leader takes years of planning and consensus.

Bitcoin developers are actively researching post-quantum cryptographic standards to keep the network safe over the long term.

Some developers have proposed upgrades to adopt quantum-resistant signature schemes. Others support proposals to freeze permanently exposed, inactive addresses if necessary.

For everyday crypto users, practicing good wallet hygiene remains a simple line of defense.

Most modern Bitcoin wallets automatically generate new addresses for every transaction, preventing accidental key exposure.