import ecdsa
from hashlib import sha256


class Verifier:
    def verify_rfc6979(self, public_key: bytes, message: bytes, signature: bytes) -> bool:
        if len(public_key) == 0 or public_key is None:
            raise ValueError(f"Incorrect public key: {public_key}")

        if message is None or signature is None:
            return False

        vk = ecdsa.VerifyingKey.from_string(public_key, curve=ecdsa.SECP256k1, hashfunc=sha256)

        try:
            return vk.verify(signature, message)
        except ecdsa.BadSignatureError:
            return False