A technical assessment of how quantum computers running Shor's algorithm threaten public blockchain addresses, private keys, and decentralized consensus.
Both Bitcoin and Ethereum rely on the secp256k1 elliptic curve. While addresses that have never spent funds are protected by the one-way preimage resistance of SHA-256 and Keccak-256, any address that has ever broadcast a transaction has revealed its uncompressed public key to the world, leaving it vulnerable to instant private key derivation by a quantum computer.
We review modern physical quantum architecture estimates: a fault-tolerant quantum computer with approximately 2,000 to 4,000 logical qubits (translating to roughly 2 to 4 million physical qubits using surface codes) could solve the discrete logarithm problem for secp256k1 in less than 10 minutes.
Analyzing proposed emergency recovery hard-forks: freezing vulnerable addresses, enforcing mandatory migration to post-quantum account abstraction wallets, and transitioning consensus validators to ML-DSA signatures.