package s1;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.security.SecureRandom;
import java.util.Base64;
public class DES {
    private static final String ALGORITHM = "DES";
    private static final String TRANSFORMATION = "DES/ECB/PKCS5Padding";
    public static void main(String[] args) throws Exception {
        String plainText = "Hello, world!"; // 要加密的明文
        // 生成随机密钥
        SecretKey secretKey = generateRandomKey();
        // 加密明文
        byte[] cipherText = encrypt(plainText.getBytes(), secretKey);
        // 将密文转换为 Base64 编码字符串
        String encodedCipherText = Base64.getEncoder().encodeToString(cipherText);
        System.out.println("密文：" + encodedCipherText);
        // 解密密文
        byte[] decryptedText = decrypt(Base64.getDecoder().decode(encodedCipherText), secretKey);
        System.out.println("解密后的明文：" + new String(decryptedText));
    }
    /**
     * 生成随机密钥
     */
    public static SecretKey generateRandomKey() throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM);
        SecureRandom secureRandom = new SecureRandom();
        keyGenerator.init(secureRandom);
        return keyGenerator.generateKey();
    }
    /**
     * 使用指定的密钥加密数据
     */
    public static byte[] encrypt(byte[] data, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(data);
    }
    /**
     * 使用指定的密钥解密数据
     */
    public static byte[] decrypt(byte[] data, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(data);
    }
}