Technical dictionary
ECDSA (secp256k1 on Bitcoin)
Elliptic-curve signature scheme used widely on Bitcoin; breakable by Shor’s algorithm given the public key.
Definition
ECDSA with the secp256k1 curve authorizes typical Bitcoin spends. Classically secure at current parameters against known non-quantum attacks when implemented correctly.
A CRQC running Shor-class algorithms could recover private keys from public keys—hence the quantum migration problem for UTXO authorization.