The Google paper released yesterday (March 31) specifically highlighted that 6.9 million BTC are currently "at-rest vulnerable" because of their address type.
Here is the breakdown of how your specific address type holds up against a quantum attacker:
1. The "Exposed" Group (High Risk)
These addresses have their Public Keys written directly on the blockchain in plain sight. A quantum computer doesn't need to wait for you to spend; it can start the math right now.
• P2PK (Legacy/Satoshi Era): Used for the first ~1.7 million BTC mined (2009–2010). These are the most vulnerable.
• P2TR (Taproot - bc1p...): To make Taproot fast and private, it commits a "tweaked" Public Key directly to the chain. While it’s the best for current fees, it is technically an "at-rest" vulnerability compared to older hashed types.
• Reused Addresses: If you have ever sent Bitcoin out of an address and then received more back into that same address, your Public Key is now permanently "naked" on the ledger.
2. The "Hashed" Group (Safe while "At-Rest")
These addresses only store a hash (a digital fingerprint) of your key. Even a 500,000-qubit computer cannot "see" the key to attack it while the coins are just sitting there.
• P2PKH (Legacy - 1...): The original "hashed" address. Safe until you spend.
• P2WPKH (Native SegWit - bc1q...): This is the current "Gold Standard" for 2026. It is cheap, fast, and keeps your Public Key hidden behind a quantum-resistant SHA-256 wall.
3. The "Quantum-Hardened" Group (Future Proof)
This is the new frontier being discussed this week in the Bay Area dev circles.
• P2MR (BIP-360 - bc1z...): This is the "Satoshi Fix" merged earlier this year. It works like Taproot but removes the key-path. It only commits to a Merkle root of scripts. It is designed to be the "Forever Vault" that you can leave your coins in for 50 years without worrying about quantum breakthroughs.
The 2026 Strategy: If you have funds in an old 1... or 3... address that you've used before, or a large stack in a Taproot bc1p address, the "Smart Money" is currently migrating those to a fresh, never-used bc1q address (or a bc1z if your wallet supports the BIP-360 testnet yet).