请用java实现sm4的加密过程

好的，以下是Java实现SM4加密过程的示例代码：

import org.bouncycastle.crypto.engines.SM4Engine;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
import org.bouncycastle.util.Arrays;

import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;

public class SM4Encryption {
    public static byte[] encrypt(byte[] key, byte[] iv, byte[] plaintext) throws Exception {
        // Create the SM4 cipher engine
        SM4Engine sm4engine = new SM4Engine();

        // Use CBC mode with PKCS#7 padding
        PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(sm4engine));

        // Create the key and IV parameters
        KeyParameter keyParam = new KeyParameter(key);
        ParametersWithIV params = new ParametersWithIV(keyParam, iv);

        // Initialize the cipher engine with the key and IV parameters
        cipher.init(true, params);

        // Encrypt the plaintext
        byte[] ciphertext = new byte[cipher.getOutputSize(plaintext.length)];
        int len = cipher.processBytes(plaintext, 0, plaintext.length, ciphertext, 0);
        cipher.doFinal(ciphertext, len);

        return ciphertext;
    }

    public static void main(String[] args) throws Exception {
        // Generate a random 128-bit key and 128-bit IV
        SecureRandom random = new SecureRandom();
        byte[] key = new byte[16];
        byte[] iv = new byte[16];
        random.nextBytes(key);
        random.nextBytes(iv);

        // Encrypt a plaintext message
        String plaintext = "Hello, world!";
        byte[] ciphertext = encrypt(key, iv, plaintext.getBytes(StandardCharsets.UTF_8));

        System.out.println("Plaintext: " + plaintext);
        System.out.println("Key: " + Arrays.toString(key));
        System.out.println("IV: " + Arrays.toString(iv));
        System.out.println("Ciphertext: " + Arrays.toString(ciphertext));
    }
}

在上面的示例代码中，我们使用了Bouncy Castle库中的SM4算法实现了加密。代码中首先生成一个随机的128位密钥和128位初始向量，然后使用SM4算法对明文进行加密。最后输出明文、密钥、初始向量和密文。注意，这里的加密过程是使用CBC模式和PKCS#7填充方式。