Are Your Bitcoins Safe from Quantum Computers?
Quantum computers are powerful machines that, in the future, might be able to break Bitcoin security. Today it’s still not possible, but experts are watching closely.
There are two possible attack methods:
1. During transaction confirmation
- When you send Bitcoin, your public key becomes visible for a short time (in the “mempool” before it’s added to a block).
- If a quantum computer could quickly calculate your private key from that public key—faster than 10 minutes—it could steal your Bitcoin.
- Luckily, current quantum computers are not strong enough to do this.
2. Harvest-now, decrypt-later
- This is a more realistic threat.
- Old or reused Bitcoin addresses could be unsafe if their public keys are already visible.
- Hackers might “collect” these public keys now and try to break them in the future when quantum tech improves.
Project Eleven’s Solution
Project Eleven has released a tool to check if your Bitcoin addresses are vulnerable.
- If your address is on the list, move your Bitcoin to a safer one.
- If the issue is because of reused addresses, you can keep the same wallet but just generate a new address.
- If it’s because of an old address format, you should move your coins to a newer wallet that creates “quantum-resistant” addresses.
Which Addresses Are Safe vs. Unsafe?
- Vulnerable:
- P2PK (Pay-To-Public-Key) (very old, before 2011)
- Some P2TR (Taproot) addresses (start with bc1p)
- Safe (quantum-resistant):
- P2PKH (start with 1)
- P2SH (start with 3)
- P2WPKH (start with bc1q)
Examples:
- Safe P2WPKH: bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
- Safe P2PKH: 1HsK3s3o1nBVsB7rKAvwF7v9mvhT2HwZq8
- Safe P2SH: 3DymAvEWH38HuzHZ3VwYAQr8YTzTUpmsnA
Common Questions
1. If one address in my wallet is exposed, are all of them in danger?
No. Modern wallets (like Ledger, Trezor, Electrum) use HD technology, meaning each address has its own private key. Only the exposed address is at risk—unless your xpub (master public key) is leaked. Never share it.
2. If I spend part of my Bitcoin from an address, is the rest still at risk?
No. When you spend, your wallet sends all the coins from that address, then sends the leftover back to a new safe address. The old address becomes empty and should not be reused.
