javax.crypto.BadPaddingException：错误 [英] javax.crypto.BadPaddingException: error

问题描述

我正在尝试运行一个简单的加密/解密程序。我得到一个填充异常。必须有隐藏的东西，我不知道。我基本上加密了将一个字符串写入一个文件，读回来并对其进行解密。原始的加密数组解密没有问题。我将原始的加密数组与从文件读回的数组进行了比较，与我可以看到的相同。文件的缓冲区不起作用，所以必须有区别。我不知道该怎么做。

  import java.security。*; 
 import java.security.spec.InvalidKeySpecException; 
 import javax.crypto.Cipher; 
 import javax.crypto.spec.SecretKeySpec; 
 
 import java.io. *; 
 
 public class sample 
 {
 private static String _algo =AES; 
 private static byte [] _key = new byte [16]; 
 
 public static byte [] encrypt（String val）throws异常
 {
 Key key = new SecretKeySpec（_key，_algo）; 
密码c = Cipher.getInstance（_algo）; 
 
 c.init（Cipher.ENCRYPT_MODE，key）; 
 
 byte [] encode = c.doFinal（val.getBytes（））; 
 
 return encode; 
} 
 
 public static String decrypt（byte [] val）throws异常
 {
 Key key = new SecretKeySpec（_key，_algo）; 
密码c = Cipher.getInstance（_algo）; 
 
 c.init（Cipher.DECRYPT_MODE，key）; 
 
 byte [] decode = c.doFinal（val）; 
 
 String decodeStr = new String（decode）; 
 
 return decodeStr; 
} 
 
 public static void main（String [] args）throws异常
 {
 String str =再见残酷的世界; 
 
 // 
 //从命令行获取密码
 // 
 _key = args [0] .getBytes（）; 
 
 byte [] encodeArray = sample.encrypt（str）; 
 
 // 
 //将加密数组写入文件
 // 
 FileOutputStream os = new FileOutputStream（data）; 
 os.write（encodeArray）; 
 os.close（）; 
 
 // 
 //解码并打印出字符串
 // 
 String decodeStr = sample.decrypt（encodeArray）; 
 System.out.println（decodeStr =+ decodeStr）; 
 
 // 
 //读回加密字符串
 byte [] buffer = new byte [64]; 
 FileInputStream is = new FileInputStream（data）; 
 is.read（buffer）; 
 is.close（）; 
 
 decodeStr = sample.decrypt（buffer）; 
 System.out.println（decodeStr =+ decodeStr）; 
} 
} 
  

输出： p>

  java示例1234567890123456 
 decodeStr =再见残酷世界
线程main中的异常javax.crypto.BadPaddingException ：给最终块没有正确填充
在com.sun.crypto.provider.SunJCE_f.b（DashoA13 * ..）
在com.sun.crypto.provider.SunJCE_f.b（DashoA13 * .. ）
在com.sun.crypto.provider.AESCipher.engineDoFinal（DashoA13 * ..）
在javax.crypto.Cipher.doFinal（DashoA13 * ..）
在sample.decrypt（ sample.java:32）
在sample.main（sample.java:70）
  

解决方案

问题是，你正在读取文件的大小为64的字节缓冲区太大了。将其更改为32。

或使用文件的长度如下：

  byte [] buffer = new byte [（int）new File（data）。length（）]; 
  

I am trying to run a simple encryption/decryption program. I am getting a padding exception. There must be something hidden that I am not aware. I basically encrypted a string write it to a file, read it back, and decrypted it. The original encrypted array was decrypted without a problem. I compared the original encrypted array with the array read back from the file, they were identical from what I can see. The buffer from the file does not work, so there must be something difference. I don't know what to do.

import java.security.*;  
import java.security.spec.InvalidKeySpecException;  
import javax.crypto.Cipher;  
import javax.crypto.spec.SecretKeySpec;  

import java.io.*;  

public class sample  
{  
   private static String _algo = "AES";  
   private static byte[] _key = new byte[16];  

   public static byte[] encrypt (String val) throws Exception  
   {  
      Key key = new SecretKeySpec (_key, _algo);  
      Cipher c = Cipher.getInstance (_algo);  

      c.init (Cipher.ENCRYPT_MODE, key);  

      byte[] encode = c.doFinal (val.getBytes());  

      return encode;  
   }  

   public static String decrypt (byte[] val) throws Exception    
   {  
      Key key = new SecretKeySpec (_key, _algo);  
      Cipher c = Cipher.getInstance (_algo);  

      c.init (Cipher.DECRYPT_MODE, key);  

      byte[] decode = c.doFinal (val);  

      String decodeStr = new String (decode);  

      return decodeStr;  
   }  

   public static void main (String[] args) throws Exception  
   {  
      String str = "Good bye cruel world";  

      //  
      // get password from command line  
      //  
      _key = args[0].getBytes();  

      byte[] encodeArray = sample.encrypt (str);  

      //  
      // write encrypted array to file  
      //  
      FileOutputStream os = new FileOutputStream ("data");  
      os.write (encodeArray);  
      os.close();  

      //  
      // decode and print out string  
      //  
      String decodeStr = sample.decrypt (encodeArray);  
      System.out.println ("decodeStr = " + decodeStr);  

      //  
      // read back encrypted string  
      byte[] buffer = new byte[64];  
      FileInputStream is = new FileInputStream ("data");  
      is.read (buffer);  
      is.close();  

      decodeStr = sample.decrypt (buffer);  
      System.out.println ("decodeStr = " + decodeStr);  
   }  
}  

Output:

java sample 1234567890123456  
decodeStr = Good bye cruel world  
Exception in thread "main" javax.crypto.BadPaddingException: Given final block not   properly padded  
        at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)  
        at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)  
        at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)  
        at javax.crypto.Cipher.doFinal(DashoA13*..)  
        at sample.decrypt(sample.java:32)  
        at sample.main(sample.java:70)  

解决方案

The problem is that the byte buffer with a size of 64, which you are reading the file into, is too big. Change it to 32.

Or use the length of the file like this:

byte[] buffer = new byte[(int)new File("data").length()];

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