Quantum Threat Nears: Crypto Networks Race to Upgrade by 2029

Google's research suggests quantum computers capable of breaking existing encryption could arrive by 2029. That timeline is far shorter than the crypto industry had assumed.

The mechanism is straightforward. A quantum machine would let an attacker derive a private key from a public key. On a blockchain, that means stealing coins from any wallet where the public key has been visible. And because crypto transactions are final, there is no bank or intermediary to reverse the theft.

Bitcoin faces the biggest exposure. Estimates from researchers cited in the report put 35% to 50% of its supply at risk. The reason is the network's 17-year history. Every transaction broadcasts a public key. Once quantum machines mature, those old coins become vulnerable.

Bitcoin (BTC) profile

Ethereum's foundation targets full protection by 2029 – the same year Google says the threat materializes. Algorand plans to support post-quantum accounts later this year. Neither is live on any of the top 20 blockchains.

Ethereum (ETH) profile

“It's the most direct existential threat towards cryptocurrencies and crypto networks,” said Chris Tam, head of quantum innovation at BTQ Technologies.

Utkarsh Ahuja, managing partner at Moon Pursuit Capital, said blockchains are uniquely exposed because they are transparent and permanent.

Jefferies equity strategist Christopher Wood unloaded a 10% Bitcoin allocation from his model portfolio in January, citing the long-term existential threat.

The upgrade path is slow. Post-quantum signature schemes exist but they are larger, slower, and require changes to consensus. A hard fork may be necessary. The industry has years, not decades, to coordinate.

No top-20 blockchain has deployed quantum-resistant algorithms yet.