Quantum Computers Threaten Bitcoin and Ethereum: Developers Scramble for Solutions
Imagine a locksmith who can guess your key just by looking at it. This is similar to what a powerful quantum computer would do to Bitcoin (BTC) and Ethereum (ETH). Every time you spend from a crypto address, you publish a public key. Today, using that public key to derive the matching private key would take longer than the universe has been around.
A big enough quantum machine running Shor's algorithm can turn this into an afternoon. Google Quantum AI estimates it would take 18-23 minutes with about 500,000 physical qubits. Researchers from the Ethereum Foundation and Stanford co-signed a paper on this topic.
Cryptocurrency developers have to prepare for the early guess because you cannot patch a decentralized network overnight. Today's quantum-resistant encryption algorithms are not new. The National Institute of Standards and Technology finished standardizing its first post-quantum algorithms in 2024, including ML-DSA and SLH-DSA.
However, these new algorithms are chunky. They are bigger and slower than the current elliptic curve signatures used by crypto. On a blockchain, every computing node stores every signature forever. Swapping them in would be like replacing every door in a skyscraper with a bank vault door - safer but heavier, pricier, and slower to open.
Bitcoin's contribution is BIP 360, which adds a new address type called P2MR. This lets people opt into quantum-resistant signatures later without dragging the whole network through a hard-fork fight. Ethereum is being more aggressive in this area, with its Post-Quantum Security team and Lean Ethereum plan.
Outside of Bitcoin and Ethereum, Algorand has already performed real transactions signed with the quantum-resistant Falcon-1024 algorithm. Zcash is funding a project to bring quantum-proof private transactions directly to hardware security chips. Wallet makers are also on the move, such as the Trezor Safe 7 and Ledger group.