Question

我知道这个问题经常被问到但是我已经检查了我在Stack Overflow中找到的所有内容并且没有找到问题的解决方案。
我使用DESede进行加密和解密，并使用外部24字节键输入。但得到例外。

这是我的代码：

    import java.security.InvalidKeyException;
    import java.security.NoSuchAlgorithmException;
    import java.security.spec.InvalidKeySpecException;

    import javax.crypto.BadPaddingException;
    import javax.crypto.Cipher;
    import javax.crypto.IllegalBlockSizeException;
    import javax.crypto.SecretKeyFactory;
    import javax.crypto.NoSuchPaddingException;
    import javax.crypto.SecretKey;
    import javax.crypto.spec.DESedeKeySpec;
    import javax.xml.bind.DatatypeConverter;

    public class DESede {

     private static Cipher encryptCipher;
     private static Cipher decryptCipher;

     public static void main(String[] args) throws InvalidKeySpecException {
      try {


       String desKey = "0123456789abcdef0123456789abcdef0123456789abcdef"; // value from user
       byte[] keyBytes = DatatypeConverter.parseHexBinary(desKey);
       System.out.println((int)keyBytes.length);

       SecretKeyFactory factory = SecretKeyFactory.getInstance("DESede");
       SecretKey key = factory.generateSecret(new DESedeKeySpec(keyBytes));

       encryptCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
       encryptCipher.init(Cipher.ENCRYPT_MODE, key); //throwing Exception
       byte[] encryptedData = encryptData("Confidential data");

       decryptCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
       decryptCipher.init(Cipher.DECRYPT_MODE, key);
       decryptData(encryptedData);

      } catch (NoSuchAlgorithmException e) {
       e.printStackTrace();
      } catch (NoSuchPaddingException e) {
       e.printStackTrace();
      } catch (InvalidKeyException e) {
       e.printStackTrace();
      } catch (IllegalBlockSizeException e) {
       e.printStackTrace();
      } catch (BadPaddingException e) {
       e.printStackTrace();
      }

     }

//加密方法

     private static byte[] encryptData(String data)
       throws IllegalBlockSizeException, BadPaddingException {
      System.out.println("Data Before Encryption :" + data);
      byte[] dataToEncrypt = data.getBytes();
      byte[] encryptedData = encryptCipher.doFinal(dataToEncrypt);
      System.out.println("Encryted Data: " + encryptedData);

      return encryptedData;
     }

//解密方法

     private static void decryptData(byte[] data)
       throws IllegalBlockSizeException, BadPaddingException {
      byte[] textDecrypted = decryptCipher.doFinal(data);
      System.out.println("Decryted Data: " + new String(textDecrypted));
     }
    }

我在该行获得异常：java.security.InvalidKeyException：密钥长度无效：24字节

encryptCipher.init(Cipher.ENCRYPT_MODE, key);

任何人都知道为什么会这样？

Answer 1

您在代码中犯了两个错误

您使用DESede在此行中创建密钥工厂

 SecretKeyFactory factory = SecretKeyFactory.getInstance("DESede");

但您使用DES获取Cipher对象。你必须使用DESede代替

所以请使用此行

encryptCipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");

而不是这一行

encryptCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

使用相同的算法来获取decripting cipher

另一个是使用AlgorithmParameterSpec来初始化解密密码。

byte iv[] = encryptCipher.getIV(); 
IvParameterSpec dps = new IvParameterSpec(iv);
decryptCipher.init(Cipher.DECRYPT_MODE, key, dps);

您可以使用上面的代码将AlgorithmParameterSpec应用于密码的初始化

异常java.security.InvalidKeyException：无效的密钥长度：使用DESede的24个字节

1 个答案: