Java中的DES算法

如何解决Java中的DES算法

我正在尝试创建一个程序，您可以在其中使用 Java 中的 DES 算法加密/解密文本和文件。文件解密部分不起作用，我收到此异常：“javax.crypto.IllegalBlockSizeException：使用填充密码解密时，输入长度必须是 8 的倍数”。 有人可以帮我吗？

import javax.crypto.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
import java.util.Scanner;

public class Main {
   public static void main(String[] args) {
       try {
           Scanner input = new Scanner(System.in);
           KeyGenerator desKeyGenerator = KeyGenerator.getInstance("DES");
           Cipher desCipherEncrypter = Cipher.getInstance("DES");
           Cipher desCipherDecrypter = Cipher.getInstance("DES");

           SecretKey key = desKeyGenerator.generateKey();
           desCipherEncrypter.init(Cipher.ENCRYPT_MODE,key);
           desCipherDecrypter.init(Cipher.DECRYPT_MODE,key);

           System.out.print("Plaintext: ");
           String message = input.nextLine();
           String encrypted = encrypt(desCipherEncrypter,message);
           System.out.println("Encrypted text: " + encrypted);
           String decrypted = decrypt(desCipherDecrypter,encrypted);
           System.out.println("Decrypted text: " + decrypted);
           

           System.out.print("The file you want to encrypt: ");
           String path = input.nextLine();
           System.out.print("The file where you want to save the encrypted one: ");
           String fileenc = input.nextLine();
           fileencrypt(desCipherEncrypter,path,fileenc);
           System.out.print("The file where you want to save the decrypted one: ");
           String filedec = input.nextLine();
           filedecrypt(desCipherDecrypter,fileenc,filedec );

       }
       catch (NoSuchAlgorithmException noSuchAlgorithmException) {
           noSuchAlgorithmException.printStackTrace();
       } catch (InvalidKeyException invalidKeyException) {
           invalidKeyException.printStackTrace();
       } catch (NoSuchPaddingException noSuchPaddingException) {
           noSuchPaddingException.printStackTrace();
       } catch (BadPaddingException badPaddingException) {
           badPaddingException.printStackTrace();
       } catch (IllegalBlockSizeException illegalBlockSizeException) {
           illegalBlockSizeException.printStackTrace();
       } catch (FileNotFoundException e) {
           e.printStackTrace();
       } catch (Exception e) {
           e.printStackTrace();
       }

   }

   public static void fileencrypt(Cipher cipher,String path,String encryptedfile) throws FileNotFoundException,Exception{
       Scanner inputi=new Scanner(System.in);
       Scanner finput = null;
       File file = new File(path);
       if (!file.exists()) throw new FileNotFoundException();
       if (!file.canRead()) throw new Exception("Cannot read " + path);
       if (!file.canWrite()) throw new Exception("Cannot write " + path);
       finput = new Scanner(file);
       FileWriter write =new FileWriter(encryptedfile);
       while (finput.hasNext()) {
           String str = finput.nextLine();
           String encrypt = encrypt(cipher,str);
           write.write(encrypt);
           write.write("\n");
       }
       System.out.println("Encrypted text");
       write.close();
   }
   public static void filedecrypt(Cipher cipher,String filetodecrypt,String dencryptedfile) throws FileNotFoundException,Exception{
       Scanner dinput=null;
       FileWriter write1 =new FileWriter(dencryptedfile);
       File filefordecrypt=new File(filetodecrypt);
       dinput=new Scanner(filetodecrypt);
       while (dinput.hasNext()) {
           String str = dinput.nextLine();
           String decrypt = decrypt(cipher,str);
           write1.write(decrypt + " ");
       }
       write1.close();
       System.out.println("Decrypted text");
   }
   public static String encrypt(Cipher cipher,String plainStr) throws BadPaddingException,IllegalBlockSizeException
   {
       byte[] plainBytes;
       byte[] encryptedBytes;
       plainBytes=plainStr.getBytes(StandardCharsets.ISO_8859_1);
       encryptedBytes=cipher.doFinal(plainBytes);
       return Base64.getEncoder().encodeToString(encryptedBytes);
   }

   public static String decrypt(Cipher cipher,String encryptedStr) throws BadPaddingException,IllegalBlockSizeException
   {
       byte[] encryptedBytes=Base64.getDecoder().decode(encryptedStr);
       byte[] decryptedBytes=cipher.doFinal(encryptedBytes);
       return new String(decryptedBytes,StandardCharsets.ISO_8859_1);
   }


} ```