三步实现Java的SM2前端加密后端解密

在实现SM2前端加密和后端解密的过程中，需要遵循以下步骤：

1. 生成SM2公钥和私钥。
2. 使用SM2公钥加密数据。
3. 使用SM2私钥解密数据。

以下是一个简单的Java代码示例，展示了如何使用Bouncy Castle库来实现这个过程：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.engines.SM2Engine;
import org.bouncycastle.crypto.modes.GMTEncryptingState;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.crypto.digests.SM3Digest;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECPrivateKeySpec;
import org.bouncycastle.jce.spec.ECPublicKeySpec;
import java.security.KeyFactory;
import java.security.Security;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
 
public class SM2Example {
    static {
        Security.addProvider(new BouncyCastleProvider());
    }
 
    public static void main(String[] args) throws Exception {
        // 生成SM2公钥和私钥
        ECKeyPairGenerator keyGenerator = new ECKeyPairGenerator();
        keyGenerator.init(new ECKeyPairGenerator.ECKeyGenerationParameters(
                ECDomainParameters.getDomainParameters(ECDomainParameters.SM2),
                new SecureRandom()
        ));
        AsymmetricCipherKeyPair keyPair = keyGenerator.generateKeyPair();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
 
        // 使用SM2公钥加密数据
        byte[] dataToEncrypt = "Hello, SM2 Encryption!".getBytes();
        SM2Engine sm2Engine = new SM2Engine();
        sm2Engine.init(true, new ParametersWithRandom(publicKey, new SecureRandom()));
        byte[] encryptedData = sm2Engine.processBlock(dataToEncrypt, 0, dataToEncrypt.length);
 
        // 使用SM2私钥解密数据
        sm2Engine.init(false, privateKey);
        byte[] decryptedData = sm2Engine.processBlock(encryptedData, 0, encryptedData.length);
 
        // 验证解密数据的正确性
        if (Arrays.equals(dataToEncrypt, decryptedData)) {
            System.out.println("Decryption successful, original data: " + new String(decryptedData));
        } else {
            System.out.print