java实现sm4-cbc

在Java中实现SM4-CBC加密模式，你可以使用Bouncy Castle密码库来实现。以下是一个示例代码：

import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.InvalidCipherTextException;
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.encoders.Hex;

import java.nio.charset.StandardCharsets;

public class SM4CBCExample {
    public static void main(String[] args) throws InvalidCipherTextException {
        // 128-bit密钥（16字节）
        byte[] key = Hex.decode("0123456789abcdef0123456789abcdef");
        // 128-bit初始向量（16字节）
        byte[] iv = Hex.decode("0123456789abcdef0123456789abcdef");
        
        // 明文
        String plaintext = "Hello, SM4 CBC!";
        byte[] plaintextBytes = plaintext.getBytes(StandardCharsets.UTF_8);
        
        // 加密
        byte[] ciphertext = sm4CBC(key, iv, true, plaintextBytes);
        System.out.println("Ciphertext: " + Hex.toHexString(ciphertext));
        
        // 解密
        byte[] decryptedBytes = sm4CBC(key, iv, false, ciphertext);
        String decryptedText = new String(decryptedBytes, StandardCharsets.UTF_8);
        System.out.println("Decrypted Text: " + decryptedText);
    }
    
    private static byte[] sm4CBC(byte[] key, byte[] iv, boolean encrypt, byte[] data) throws InvalidCipherTextException {
        SM4Engine sm4Engine = new SM4Engine();
        CBCBlockCipher cbcBlockCipher = new CBCBlockCipher(sm4Engine);
        PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(cbcBlockCipher);
        
        CipherParameters params = new ParametersWithIV(new KeyParameter(key), iv);
        cipher.init(encrypt, params);
        
        byte[] output = new byte[cipher.getOutputSize(data.length)];
        int processedBytes = cipher.processBytes(data, 0, data.length, output, 0);
        processedBytes += cipher.doFinal(output, processedBytes);
        
        byte[] result = new byte[processedBytes];
        System.arraycopy(output, 0, result, 0, processedBytes);
        return result;
    }
}

这个示例使用Bouncy Castle库进行SM4-CBC算法的加密和解密操作。你需要将Bouncy Castle库添加到项目的依赖中。在示例中，我们使用了一个128-bit的密钥和初始向量（IV），明文为"Hello, SM4 CBC!"。加密后的密文以十六进制形式打印出来，并通过解密操作验证解密结果。

请注意，本示例仅供参考，实际应用中可能需要根据具体需求进行适当的修改和优化。