如何使用BouncyCastle验证ASN.1格式的ECDSA签名和DER中的公钥？

import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.DERBitString;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.signers.ECDSASigner;
import org.bouncycastle.crypto.signers.ECDSASignerWithRecovery;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Base64;
import java.security.Security;
import java.security.Signature;
import java.security.SignatureException;
import java.security.spec.ECPoint;
import java.security.spec.ECPublicKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;

Security.addProvider(new BouncyCastleProvider());

byte[] derPublicKeyBytes = Base64.decode(derPublicKeyBase64);
ASN1InputStream asn1InputStream = new ASN1InputStream(derPublicKeyBytes);
ASN1Primitive asn1Primitive = asn1InputStream.readObject();
SubjectPublicKeyInfo subjectPublicKeyInfo = SubjectPublicKeyInfo.getInstance(asn1Primitive);
ECPublicKeyParameters ecPublicKeyParameters = (ECPublicKeyParameters) PublicKeyFactory.createKey(subjectPublicKeyInfo);

byte[] signatureBytes = Base64.decode(signatureBase64);
byte[] messageBytes = message.getBytes("UTF-8");

ECDSASigner ecdsaSigner = new ECDSASignerWithRecovery();
ecdsaSigner.init(false, ecPublicKeyParameters.getParameters());
ecdsaSigner.update(messageBytes, 0, messageBytes.length);

boolean signatureValid = ecdsaSigner.verifySignature(signatureBytes);

if (signatureValid) {
    System.out.println("Signature is valid.");
} else {
    System.out.println("Signature is invalid.");
}