使用Blowfish在Java中解密 [英] Decrypting in Java with Blowfish

问题描述

Hullo，

我正在使用Blowfish在Java中加密和解密。

加密工作正常，但解密失败。

这是我的解密代码：

  String encryptedString = ...; 
 String decryptptedString = null; 
 SecretKeySpec key = new SecretKeySpec（myKey.getBytes（），Blowfish）; 
密码密码; 
 try {
 cipher = Cipher.getInstance（Blowfish）; 
 cipher.init（Cipher.DECRYPT_MODE，key）; 
 byte [] decryptpted = cipher.doFinal（encryptedString.getBytes（））; 
 decryptptedString = new String（解密，Charset.forName（UTF-8））; 
} [捕获异常...] 
  

我收到一个例外：

异常。 javax.crypto.IllegalBlockSizeException：使用填充密码进行解密时，输入长度必须是8的倍数。

你能告诉我如何使其简单的工作？谢谢。

我输入的输入来自我的加密Java代码，Base64中的+编码，我在将其解密到Base64之前就已经被解密了。 / p>

解决方案

现在我有解决方案！

首先， Unicode的问题，所以我把ISO-8859-1无处不在。 包括Base64编码和解码。

然后，我以下是我的Java代码，它适用于Blowfish解密：

  String encryptedString = ...; 
 String decryptptedString = null; 
 SecretKeySpec key = new SecretKeySpec（myKey.getBytes（CHARSET_ISO_8859_1），Blowfish）; 
密码密码; 
 try {
 cipher = Cipher.getInstance（Blowfish / ECB / PKCS5Padding）; 
 cipher.init（Cipher.DECRYPT_MODE，key）; 
 byte [] decryptpted = cipher.doFinal（encryptedString.getBytes（CHARSET_ISO_8859_1））; 
 decryptptedString = new String（解密，CHARSET_ISO_8859_1）; 
} [catch例外...] 
  

请注意，我已经替换了 c code code code code code code code code code code code $但是，如果您对密钥执行相同操作，则失败。

密钥 myKey 必须是拉丁文-1字符串，8个字符。这使得128位的键。 Blowfish算法允许更大的密钥，但由于JRE中的美国出口限制，它们在Java中失败 - 美国允许加密，但不能比 NSA 可以中断。

CHARSET_ISO_8859_1 是一个常量定义如下所示：

  final Charset CHARSET_ISO_8859_1 = Charset.forName（ISO-8859-1）; 
  

和 Charset 是



最后但并非最不重要的是，我已经相应地更改了加密Java代码。

Hullo,

I am encrypting and decrypting in Java with Blowfish.

The encryption works fine, but the decryption fails.

Here is my Java code for decrypting :

String encryptedString = … ;
String decryptedString = null;
SecretKeySpec key = new SecretKeySpec(myKey.getBytes(), "Blowfish");
Cipher cipher;
try {
    cipher = Cipher.getInstance("Blowfish");
    cipher.init(Cipher.DECRYPT_MODE, key);
    byte[] decrypted = cipher.doFinal(encryptedString.getBytes());
    decryptedString = new String(decrypted, Charset.forName("UTF-8"));
} [ catch Exceptions … ]

I get an exception :

Exception. javax.crypto.IllegalBlockSizeException: Input length must be multiple of 8 when decrypting with padded cipher

Can you tell me how to make this simply work ? Thank you.

The input I give comes from my encryption Java code, + encoding in Base64, and I decode it from Base64 just before giving it to this decrypting operation.

解决方案

Now I have the solution !

First, there were some problems with Unicode, so I have put ISO-8859-1 everywhere. Including in the Base64 encoding and decoding.

Then, I have juggled with the variants.

Here is my Java code which works for Blowfish decryption :

String encryptedString = … ;
String decryptedString = null;
SecretKeySpec key = new SecretKeySpec(myKey.getBytes(CHARSET_ISO_8859_1), "Blowfish");
Cipher cipher;
try {
    cipher = Cipher.getInstance("Blowfish/ECB/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, key);
    byte[] decrypted = cipher.doFinal(encryptedString.getBytes(CHARSET_ISO_8859_1));
    decryptedString = new String(decrypted, CHARSET_ISO_8859_1);
} [ catch Exceptions … ]

Note that I have replaced "Blowfish" with "Blowfish/ECB/PKCS5Padding" for getting the Cipher instance, but, if you do the same for the key, it fails.

The key myKey has to be a Latin-1 string of 8 characters. This makes a key of 128 bits. The Blowfish algorithm allows bigger keys, but they fail in Java because of the USA export restriction in the JRE — the USA allow encryption but not stronger than what the NSA can break.

The CHARSET_ISO_8859_1 is a constant defined like this :

final Charset CHARSET_ISO_8859_1 = Charset.forName("ISO-8859-1");

And Charset is java.nio.charset.Charset.

Last but not least, I have changed my encryption Java code accordingly.

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