javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a

文章目录

• 一、发现问题
• 二、分析问题
• 三、解决问题
• • 3.1 方法一：不要用openjdk
  • 3.2 方法二：修改KeyGenerator.init
  • 四、全部源码

    一、发现问题

    javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption.
    	at java.base/com.sun.crypto.provider.CipherCore.unpad(CipherCore.java:977)
    	at java.base/com.sun.crypto.provider.CipherCore.fillOutputBuffer(CipherCore.java:1058)
    	at java.base/com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:855)
    	at java.base/com.sun.crypto.provider.DESCipher.engineDoFinal(DESCipher.java:314)
    	at java.base/javax.crypto.Cipher.doFinal(Cipher.java:2207)
    

    二、分析问题

    这是一个des解密的代码，在执行cipher.doFinal()的时候报错：BadPaddingException

    public static String decrypt(String keyStr,String content){ try { Key key = loadKey(keyStr);
            Cipher cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.DECRYPT_MODE,key);
            byte[] source =Base64.getDecoder().decode(content.getBytes(StandardCharsets.UTF_8));
            return new String(cipher.doFinal(source),StandardCharsets.UTF_8);
        }catch (Exception e){ e.printStackTrace();
            return null;
        }
    }
    

    三、解决问题

    • 这边有两个方法，两个方法都能解决问题，二选一即可。

      3.1 方法一：不要用openjdk

      3.2 方法二：修改KeyGenerator.init

      generator.init(new SecureRandom(keyStr.getBytes(StandardCharsets.UTF_8)));

      修改成

      SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
      secureRandom.setSeed(keyStr.getBytes());
      generator.init(secureRandom);
      

      四、全部源码

       private static Key loadKey(String keyStr){ Key key = null;
              try { KeyGenerator generator = KeyGenerator.getInstance("DES");
      //            generator.init(new SecureRandom(keyStr.getBytes(StandardCharsets.UTF_8)));
                  SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
                  secureRandom.setSeed(keyStr.getBytes());
                  generator.init(secureRandom);
                  key = generator.generateKey();
              }catch (Exception e){ e.printStackTrace();
              }
              return key;
          }
          public static String encrypt(String keyStr,String content){ try { Key key = loadKey(keyStr);
                  Cipher cipher = Cipher.getInstance("DES");
                  cipher.init(Cipher.ENCRYPT_MODE,key);
                  byte[] source = cipher.doFinal(content.getBytes(StandardCharsets.UTF_8));
                  return new String(Base64.getEncoder().encode(source),StandardCharsets.UTF_8);
              }catch (Exception e){ e.printStackTrace();
                  return null;
              }
          }
          public static String decrypt(String keyStr,String content){ try { Key key = loadKey(keyStr);
                  Cipher cipher = Cipher.getInstance("DES");
                  cipher.init(Cipher.DECRYPT_MODE,key);
                  byte[] source =Base64.getDecoder().decode(content.getBytes(StandardCharsets.UTF_8));
                  return new String(cipher.doFinal(source),StandardCharsets.UTF_8);
              }catch (Exception e){ e.printStackTrace();
                  return null;
              }
          }
      

      觉得好，就一键三连呗（点赞+收藏+关注）