Bitcoin encryption isn’t at risk from quantum computers for one simple reason: it doesn’t actually exist

The common fear that quantum computers will "crack" Bitcoin encryption is based on a misunderstanding; Bitcoin does not use encryption on-chain, as the blockchain is a public ledger.

The actual quantum threat involves a cryptographically relevant quantum computer using Shor's algorithm to derive a private key from an *exposed* public key, enabling signature forgery for spending coins. This risk hinges on public-key exposure, which occurs when transactions are spent or through address reuse, as many address formats only reveal the public key upon spending.

Tools like Project Eleven's "Bitcoin Risq List" can track the approximately 6.7 million BTC currently held in addresses with exposed public keys. Estimates suggest breaking 256-bit ECC requires around 2,330 logical qubits, translating to millions of physical qubits and significant runtime (minutes to days). The challenge is thus a migration one, requiring the adoption of quantum-resistant signatures (like those proposed in BIP 360) to replace vulnerable spending paths before fault-tolerant quantum computers become feasible, which industry roadmaps suggest is still years away (e.g., IBM targeting around 2029 for fault-tolerant systems).

(Source：CryptoSlate)