Java解密期间的BadPaddingException

Question

我是加密的新Java。 尝试实现一些轻量级的功能，以加密字符串并将其存储在某个位置，然后在使用之前将其解密。

通过一些网络搜索，我想到了进行加密和解密的方法。

   public static String base64Encode(byte[] bytes)
    {
        return new BASE64Encoder().encode(bytes);
    }

   public static byte[] base64Decode(String property) throws IOException
    {
        return new BASE64Decoder().decodeBuffer(property);
    }


    public static String encrypt(String mystring) throws GeneralSecurityException, UnsupportedEncodingException
       {
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
        SecretKey key = keyFactory.generateSecret(new PBEKeySpec(mystring.toCharArray()));
        Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
        pbeCipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(SALT, 20));
        return base64Encode(pbeCipher.doFinal(mystring.getBytes("UTF-8")));
        }

    public static String decrypt(String estring) throws GeneralSecurityException, IOException
        {
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
        SecretKey key = keyFactory.generateSecret(new PBEKeySpec(estring.toCharArray()));
        Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
        pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(SALT, 20));
        return new String(pbeCipher.doFinal(base64Decode(estring)), "UTF-8");
        }

我看到加密有效，但在doFinal块的解密部分中看到了与填充相关的异常。 这里是...

 encrypted string:zdrtgOKfkZMgpCOflr1ILQ==  -> Encrypted String
 exceptionjavax.crypto.BadPaddingException: Given
 final block not properly padded -> Exception from the doFinal block.

好像当我加密它时，我需要做某种填充。

谁能告诉我哪里出了问题以及如何解决？

谢谢

塔斯

Answer 1

您在此处使用基于密码的加密。 这意味着加密密钥本身是基于密码的。 加密和解密必须使用相同的密码。

private static char[] ENCRYPTION_PASSWORD
     = "some password populated by configuration".toCharArray();

public static String encrypt(String mystring)
  throws GeneralSecurityException, UnsupportedEncodingException {
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
    SecretKey key = keyFactory.generateSecret(new PBEKeySpec(ENCRYPTION_PASSWORD));
    Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
    pbeCipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(SALT, 20));
    return DatatypeConverter
        .printBase64Binary(pbeCipher.doFinal(mystring.getBytes("UTF-8")));
}

public static String decrypt(String string)
  throws GeneralSecurityException, IOException {
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
    SecretKey key = keyFactory.generateSecret(new PBEKeySpec(ENCRYPTION_PASSWORD));
    Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
    pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(SALT, 20));
    return new String(pbeCipher.doFinal(DatatypeConverter
                                           .parseBase64Binary(estring)), "UTF-8");
}

还要注意将javax.xml.bind.DatatypeConverter用于base64操作。 这些天无需自己编写或使用第三方。

Answer 2

您将需要首先将您对解密方法的输入进行解码。

在您的decrypt方法中调用base64Decode方法和estring参数。

那应该做。

Answer 3

更改您的代码，

SecretKey key = keyFactory.generateSecret(new PBEKeySpec(mystring.toCharArray()));

至

SecretKey key = keyFactory.generateSecret(new PBEKeySpec("PASSWORD".toCharArray(), SALT, 20));