Go from Microallen recently need to use C # des decryption tool class to decrypt the string, but to decrypt the string is to use Java for DES encryption, to the online check on the C # and Java on the DES Encryption and decryption of the data, found that can encrypt each other decryption, Java for DES encryption will generally be written as follows:
public static byte[] Encrypt (string message, String key) throws Exception {
Cipher Cipher = cipher.getinstance ("des/cbc/pkcs5padding");
Deskeyspec Deskeyspec = new Deskeyspec (key.getbytes ("UTF-8"));
Secretkeyfactory keyfactory = secretkeyfactory.getinstance ("DES");
Secret key
Secretkey Secretkey = Keyfactory.generatesecret (Deskeyspec);
Offset amount
Ivparameterspec IV = new Ivparameterspec (key.getbytes ("UTF-8"));
Cipher.init (Cipher.encrypt_mode, Secretkey, iv);
Return cipher.dofinal (Message.getbytes ("UTF-8"));
}
Because the key and offset are set when initializing the cipher, the DESCryptoServiceProvider class of C # can be easily decrypted. The C # decryption code is as follows:
public static string Decode (String str, string key)
{
Try
{
DESCryptoServiceProvider Provider = new DESCryptoServiceProvider ();
Secret key
Provider. Key = Encoding.ASCII.GetBytes (key. Substring (0, 8));
Offset amount
PROVIDER.IV = Encoding.ASCII.GetBytes (key. Substring (0, 8));
byte[] buffer = new BYTE[STR. LENGTH/2];
for (int i = 0; i < str. LENGTH/2); i++)
{
int num2 = Convert.ToInt32 (str. Substring (i * 2, 2), 0x10);
Buffer[i] = (byte) num2;
}
MemoryStream stream = new MemoryStream ();
CryptoStream stream2 = new CryptoStream (stream, provider. CreateDecryptor (), cryptostreammode.write);
Stream2. Write (buffer, 0, buffer. Length);
Stream2. FlushFinalBlock ();
Stream. Close ();
Return encoding.getencoding ("GB2312"). GetString (stream. ToArray ());
}
catch (Exception) {return "";}
}
Now the problem is that Java's DES encryption has more than one notation, and the string I need to decrypt is encrypted using the following Java code:
public static byte[] Encrypt (string message, String key) throws Exception {
securerandom sr = new SecureRandom ();
Cipher Cipher = cipher.getinstance ("DES");
Deskeyspec Deskeyspec = new Deskeyspec (key.getbytes ("UTF-8"));
Secretkeyfactory keyfactory = secretkeyfactory.getinstance ("DES");
Secretkey Secretkey = Keyfactory.generatesecret (Deskeyspec);
Another init method is used here.
Cipher.init (Cipher.encrypt_mode, Secretkey, SR);
Return cipher.dofinal (Message.getbytes ("UTF-8"));
}
In this case, the Java encryption offset is not set, and the test finds that even if the offset is set above, Cipher Cipher = cipher.getinstance ("DES"), and Cipher Cipher = cipher.getinstance ("des/cbc/pkcs5padding"); The results are different after encryption,
So the use of C # decryption when you do not know the corresponding offset should be how to set, trouble you master guidance, thank you
Supplementary questions:
DES encryption and decryption results generally note the place: Key, offset, block cipher mode, fill mode Java DES encryption when: If you use this method, Cipher Cipher = cipher.getinstance ("DES"); At this time block cipher mode with the ECB mode, the C#des class default mode is CBC mode, so if Java uses the above method to initialize, when using C # decryption to remember to set the Mode property to the ECB, in addition, if there is no set offset, C # When decrypting the key and IV are set to the same can be normal decryption. So for the 2nd des encryption method above Java, use C # decryption only need to add provider before decryption. Mode = CIPHERMODE.ECB; it's ready.
Decrypting Java des encrypted strings using C # des
