Half of the top 20 quantum-exposed bitcoin addresses belong to exchanges and custodians, holding ~1.06M BTC

We scan the whole UTXO set weekly and match every coin against public keys that are already visible on-chain, either from an earlier spend or by design (old pay-to-pubkey and Taproot outputs).

The biggest exposed balances aren’t lost Satoshi coins. They’re custodial cold wallets that have reused the same address for years. Binance’s largest has had its key public since October 2018.

In their defense, proof-of-reserves is one reason exchanges keep stable, published addresses. But rotating to fresh ones and republishing the list is a solved problem.

For everyone else the lesson is the same: receive to a fresh address every time, and your key stays hidden until you spend.

Plain-English explainer: learnbitcoin.com/rabbit-hole/quantum-and-bitcoin

(Data source links in the comments.)