package com.dji.sample.droneairport.utils;

import org.bouncycastle.crypto.engines.SM4Engine;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.bouncycastle.crypto.paddings.PKCS7Padding;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Base64;

public class SM4Util {
    public static String encrypt(byte[] key, byte[] input) {
        PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new SM4Engine(), new PKCS7Padding());
        cipher.init(true, new KeyParameter(key));  // ECB模式下不需要IV
        byte[] output = new byte[cipher.getOutputSize(input.length)];
        int length = cipher.processBytes(input, 0, input.length, output, 0);
        try {
            length += cipher.doFinal(output, length);
        } catch (Exception e) {
            e.printStackTrace();
        }
        String encoded = Base64.getEncoder().encodeToString(Arrays.copyOf(output, length));
        return encoded;
    }

    public static byte[] decrypt(byte[] key, byte[] input) {
        PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new SM4Engine(), new PKCS7Padding());
        cipher.init(false, new KeyParameter(key));  // ECB模式下不需要IV
        byte[] output = new byte[cipher.getOutputSize(input.length)];
        int length = cipher.processBytes(input, 0, input.length, output, 0);
        try {
            length += cipher.doFinal(output, length);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return Arrays.copyOf(output, length);
    }

    public static void main(String[] args) {
        byte[] key = "jsimjrby3wqb7dbq".getBytes(StandardCharsets.UTF_8); // 16字节密钥

        // 原始明文
        String plaintext = "hello";

        System.out.println("Encoded: " + encrypt(key, plaintext.getBytes(StandardCharsets.UTF_8)));

        // 解码并解密
        byte[] decoded = Base64.getDecoder().decode(encrypt(key, plaintext.getBytes(StandardCharsets.UTF_8)));
        byte[] decrypted = decrypt(key, decoded);

        // 输出结果
        System.out.println("Plaintext: " + plaintext);
        System.out.println("Encrypted (Base64): " + encrypt(key, plaintext.getBytes(StandardCharsets.UTF_8)));
        System.out.println("Decrypted: " + new String(decrypted, StandardCharsets.UTF_8));
    }
}