我想用ECDH（secp 256 r1算法）在dart和java之间进行通信。
这是我的Dart代码：

import 'dart:convert';
import 'dart:math';
import 'dart:typed_data';
import 'package:pointycastle/export.dart';

class EcdhHandler {
  late final AsymmetricKeyPair _keyPair;
  late final ECDomainParameters _domainParameters;

  EcdhHandler.init() {
    _domainParameters = ECDomainParameters(ECCurve_secp256r1().domainName);
    var ecParams = ECKeyGeneratorParameters(_domainParameters);
    var params = ParametersWithRandom<ECKeyGeneratorParameters>(ecParams, getSecureRandom());

    var keyGenerator = ECKeyGenerator();
    keyGenerator.init(params);
    _keyPair = keyGenerator.generateKeyPair();
  }

  Uint8List getPublicKey() {
    var publicKey = _keyPair.publicKey as ECPublicKey;
    var publicPoint = publicKey.Q!.getEncoded(false);
    return publicPoint;
  }

  ECPublicKey bytesToPublicKey(Uint8List bytes) {
    var domainParams = (_keyPair.publicKey as ECPublicKey).parameters;
    var curve = domainParams!.curve;
    var point = curve.decodePoint(bytes);
    return ECPublicKey(point, domainParams);
  }

  BigInt makeSharedSecret(ECPublicKey remotePublicKey) {
    var agreement = ECDHBasicAgreement();
    var privateKey = _keyPair.privateKey as ECPrivateKey;
    agreement.init(privateKey);
    return agreement.calculateAgreement(remotePublicKey);
  }
  SecureRandom getSecureRandom() {
    var secureRandom = FortunaRandom();
    var random = Random.secure();
    List<int> seeds = [];
    for (int i = 0; i < 32; i++) {
      seeds.add(random.nextInt(255));
    }
    secureRandom.seed(KeyParameter(Uint8List.fromList(seeds)));
    return secureRandom;
  }

}

这段Java代码：

import javax.crypto.KeyAgreement;
import java.security.*;
import java.security.spec.ECGenParameterSpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;

public class ECDHHandler {
    private PublicKey publicKey;
    private KeyAgreement keyAgreement;
    private byte[] sharedSecret;

    public ECDHHandler() {
        makeKeyExchangeParams();
    }

    private void makeKeyExchangeParams() {
        try {
            KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC");
            ECGenParameterSpec secp256r1 = new ECGenParameterSpec("secp256r1");
            kpg.initialize(secp256r1);
            KeyPair kp = kpg.generateKeyPair();
            keyAgreement = KeyAgreement.getInstance("ECDH");
            keyAgreement.init(kp.getPrivate());
            publicKey = kp.getPublic();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void initializeSharedSecret(PublicKey publickey) {
        try {
            keyAgreement.doPhase(publickey, true);
            sharedSecret = keyAgreement.generateSecret();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }
    }

    public PublicKey convertByteArrayToPublicKey(byte[] bytes) {
        try {
            KeyFactory kf = KeyFactory.getInstance("EC");
            X509EncodedKeySpec pkSpec = new X509EncodedKeySpec(bytes);
            return kf.generatePublic(pkSpec);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

我在dart应用程序上用pointycastle生成公钥并将其发送到Java。

我的问题

java上的方法convertByteArrayToPublicKey无法解析字节码到ecdh公钥！
我总是收到：

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException: DerInputStream.getLength(): lengthTag=20, too big.

pointycastle: ^3.7.3 

Dart SDK version: 3.0.2 (stable) (Tue May 23 08:26:58 2023 +0000) on "linux_x64"

java version "17.0.4" 2022-07-19 LTS
Java(TM) SE Runtime Environment GraalVM EE 22.2.0 (build 17.0.4+11-LTS-jvmci-22.2-b05)
Java HotSpot(TM) 64-Bit Server VM GraalVM EE 22.2.0 (build 17.0.4+11-LTS-jvmci-22.2-b05, mixed mode, sharing)