How Does Elliptic Curve Digital Signature Algorithm (ECDSA) Protect against Preimage Attacks?

ECDSA is a digital signature algorithm, not a hash function, but it relies on cryptographic hash functions for signing. The hash of the message is signed, not the message itself.

The security of the private key, which is used to generate the public key, is protected by the mathematical difficulty of reversing the elliptic curve multiplication, not the hash function's preimage resistance. The hash function ensures message integrity before signing.