Google's quantum division said this week in a new whitepaper that future machines could break widely used encryption far more efficiently than previously estimated, including the elliptic curve cryptography that underpins Bitcoin wallets. 

The research suggests attacks that once appeared decades away may arrive sooner, with some scenarios modeling the ability to crack encryption in minutes under advanced conditions.

The findings do not imply an immediate threat.

Today's quantum computers remain far below the scale required to break modern cryptographic systems.

But the paper reduces the estimated resources needed, narrowing the gap between theory and practice and shifting attention toward preparation rather than dismissal.

Google has already set a 2029 target to transition its own systems to post-quantum cryptography, reflecting a broader shift among large technology firms and governments toward defensive planning.

Is Bitcoin under threat? 

For Bitcoin, the implications are specific and structural. The network relies on digital signatures that could, in principle, be reversed by a sufficiently powerful quantum computer. Roughly one-third of the total Bitcoin supply sits in addresses where public keys have been exposed, creating a defined set of targets under certain attack models.

Separate analyses cited in the research estimate that about 6.7 million Bitcoin may be exposed to varying degrees under quantum attack scenarios, including coins held in older address formats where public keys remain permanently visible on-chain.

More immediate concerns focus on transaction windows. When a Bitcoin transaction is broadcast, its public key becomes visible before confirmation. Google's research suggests a theoretical attacker could exploit that gap, solving for the private key within the same time frame it takes for a block to be mined.

That has shifted the conversation among developers from abstract risk to engineering timelines.

Binance founder Changpeng Zhao pushed back on what he described as exaggerated concerns, arguing that most cryptographic systems, including Bitcoin, can migrate to quantum-resistant algorithms without destabilizing the network.