Google’s Breakthrough: 1,200 Qubits Can Break Bitcoin Encryption
A recent collaboration between Google, the Ethereum Foundation, and Stanford researchers has revealed that breaking Bitcoin’s encryption might require far fewer quantum computing resources than experts previously thought. Their whitepaper shows that approximately 1,200 logical qubits could crack the elliptic curve cryptography protecting cryptocurrency wallets in just nine minutes. This represents a dramatic 20-fold reduction in physical qubits compared to earlier estimates.
The research suggests a superconducting quantum computer with fewer than 500,000 physical qubits could theoretically accomplish this feat, potentially moving the threat timeline closer to 2029 rather than beyond 2030. Faster settlement times and transparency from blockchain networks could complicate recovery efforts if wallets are compromised.
How Quantum Computers Crack Bitcoin’s Private Keys
Quantum computers threaten Bitcoin’s security by exploiting a narrow but critical window of vulnerability during transaction processing.
When someone sends Bitcoin, their public key becomes visible in the memory pool for about 10 minutes—just enough time for a quantum computer using Shor’s algorithm to crack the private key.
Think of it like leaving your house key visible while walking to your mailbox.
With sufficient qubits, quantum systems can solve the mathematical puzzle protecting wallets in roughly nine minutes.
Attackers could then create replacement transactions with higher fees, redirecting funds before the original transaction confirms.
This risk is amplified by the fact that mining difficulty and block times are designed to keep average confirmation near 10 minutes, so miners’ incentives and network timing can influence how quickly blocks are found.
When Will Quantum Computers Threaten Bitcoin Wallets?
The clock is ticking faster than experts once believed. Google’s March 2025 report moved the threat timeline to 2029, cutting years off previous 2035 estimates. Breaking Bitcoin now requires just 500,000 qubits instead of 10 million. That’s twenty times fewer than scientists thought necessary.
The quantum threat timeline has accelerated dramatically—what seemed decades away now looms just four years ahead.
Three key timeline factors:
- Current quantum computers pose zero threat to Bitcoin encryption today
- Scientists estimate future systems could crack private keys in roughly 8 hours
- The “harvest now, decrypt later” attack is already happening as hackers collect encrypted data
Most experts still believe genuine quantum danger remains about a decade away, maybe more. Institutional backing for blockchain and clearer regulations, such as MiCA in Europe, are strengthening defenses against long-term threats and encouraging investment in blockchain security upgrades.
Which Bitcoin Wallets Face the Biggest Quantum Risk?
Not all Bitcoin wallets stand on equal ground when quantum computers arrive.
P2PK addresses face the biggest danger because their public keys sit exposed on the blockchain like open doors.
Satoshi’s own million-coin stash uses this format, worth roughly $100 billion.
Reused P2PKH addresses come next, affecting about 7 million BTC that revealed keys through spending.
Even Taproot wallets, despite being newer, expose keys during transactions.
Together, roughly 25% of all Bitcoin sits in these vulnerable formats.
Multisig wallets require cracking multiple keys, offering better protection than single-signature addresses.
Quantum attacks would target exposed public keys using public-key cryptography to derive private keys.
How Many Lost Bitcoins Could Quantum Unlock?
Millions of Bitcoin sit locked in forgotten wallets, and powerful quantum computers could crack them open like digital treasure chests. Experts estimate dormant holdings worth tens of billions of dollars could become accessible once quantum technology matures around 2029.
One famous address alone holds 31,000 BTC untouched since 2010.
Recovery targets include:
- Old wallets with exposed public keys from early Bitcoin days
- Dormant addresses whose owners lost private key access
- Non-migrated funds stuck in outdated security scripts
This massive re-entry of “lost” coins would shake up Bitcoin’s circulating supply, potentially disrupting prices for everyone holding cryptocurrency today. If quantum advances enable attackers to derive private keys from public keys, they could target wallets that were previously safe under public-key cryptography.
Can Bitcoin Upgrade to Quantum-Resistant Encryption?
While quantum computers threaten to open forgotten Bitcoin fortunes, the network’s developers aren’t sitting idle.
Bitcoin’s development community actively prepares quantum-resistant defenses as computing threats emerge on the horizon.
BIP-360 introduces a clever shield called Pay to Merkle Root that hides public keys behind mathematical curtains.
Bitcoin Quantum Core 0.2 replaces vulnerable signatures with NIST-approved algorithms that laugh at quantum attacks.
The first official proposal already merged into Bitcoin’s code repository.
Developers plan staged deployments to achieve full protection by 2026, racing against Google’s 2029 quantum deadline.
Block sizes expand to 64 MiB to accommodate beefier post-quantum signatures.
It’s like upgrading from a screen door to a vault while the house stays standing.
Will Quantum Threats Change Bitcoin’s Circulating Supply?
Beyond the technical arms race, quantum computers could reshape Bitcoin’s economy in unexpected ways. If Bitcoin upgrades to quantum-resistant addresses with a migration deadline, millions of coins in old wallets could become permanently inaccessible.
Lost keys and deceased owners mean those bitcoins would vanish from circulation forever, creating unexpected scarcity.
Three supply scenarios could unfold:
- Supply shock: Moving vulnerable coins crashes prices through sudden selling pressure
- Scarcity boost: Inaccessible coins reduce available supply, potentially increasing value
- Minimal disruption: Only 10,200 BTC pose real market risk, per CoinShares analysis
The outcome depends on how many owners can migrate before deadlines expire.
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