微信支付v3最新版 java如何验签代码

以下是微信支付v3最新版Java验签代码示例：

import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

import javax.crypto.*;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class WeChatPayV3Verifier {

    private static final String ALGORITHM = "SHA256withRSA";
    private static final String SIGNATURE_ALGORITHM = "RSA";
    private static final String AES_ALGORITHM = "AES/CBC/PKCS5Padding";

    private final PublicKey publicKey;
    private final byte[] aesKey;

    public WeChatPayV3Verifier(String publicKey, String aesKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        this.publicKey = KeyFactory.getInstance(SIGNATURE_ALGORITHM).generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(publicKey)));
        this.aesKey = Base64.getDecoder().decode(aesKey);
    }

    public boolean verify(String message, String signature, String nonce, String timestamp, String serialNo) throws NoSuchAlgorithmException, InvalidKeyException, SignatureException {
        String content = message + "\n" + timestamp + "\n" + nonce + "\n";
        Signature sign = Signature.getInstance(ALGORITHM);
        sign.initVerify(publicKey);
        sign.update(content.getBytes());
        return sign.verify(Base64.getDecoder().decode(signature));
    }

    public String decrypt(String ciphertext, String nonce) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
        byte[] ciphertextBytes = Base64.getDecoder().decode(ciphertext);
        byte[] nonceBytes = Base64.getDecoder().decode(nonce);
        Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
        SecretKeySpec keySpec = new SecretKeySpec(aesKey, "AES");
        IvParameterSpec ivSpec = new IvParameterSpec(nonceBytes);
        cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
        byte[] decrypted = cipher.doFinal(ciphertextBytes);
        return new String(decrypted);
    }
}

使用示例：

String publicKey = "微信支付平台公钥";
String aesKey = "商户平台API密钥";
String message = "待验签的消息体";
String signature = "消息体的签名";
String nonce = "随机数";
String timestamp = "时间戳";
String serialNo = "证书序列号";

WeChatPayV3Verifier verifier = new WeChatPayV3Verifier(publicKey, aesKey);
boolean verifyResult = verifier.verify(message, signature, nonce, timestamp, serialNo);
String decryptedMessage = verifier.decrypt(ciphertext, nonce);