The DES algorithm has been around for a long time, and the 56-bit version is now
easily crackable (in less than a day on fairly most equipment). An enhancement, and one which is still fairly compatible with DES, is the 3-DES algorithm. It
has three phases, and splits the key into two. Overall the key size is typically 112 bits (with a combination of the three keys - of which two of the keys are the same). The algorithm is EncryptK3( DecryptK2( EncryptK1(message), where K1 and K3 are typically the same (to keep compatability).
and to test, the decrypted text is:
In this case, if we try "test" as the key we get:
"Specified key is a known weak key for 'TripleDES' and cannot be used."
and it will not encrypt.
As a test: "Hello how are you?" with a stronger key of "m65hhhgfd" which should give:
The code is:
TripleDES threedes = new TripleDESCryptoServiceProvider();
threedes.Key = StringToByte(this.tbKey.Text, 24); // convert to 24 characters
- 192 bits
threedes.IV = StringToByte(" ");
byte key = threedes.Key;
byte IV = threedes.IV;
ICryptoTransform encryptor = threedes.CreateEncryptor(key, IV);
MemoryStream msEncrypt = new MemoryStream();
CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
// Write all data to the crypto stream and flush it.
csEncrypt.Write(StringToByte(this.tbMessage.Text), 0, StringToByte(this.tbMessage.Text).Length);
// Get the encrypted array of bytes.
byte encrypted = msEncrypt.ToArray();
this.tbEncrypt.Text = ByteToString(encrypted);
ICryptoTransform decryptor = threedes.CreateDecryptor(key, IV);
// Now decrypt the previously encrypted message using the decryptor
MemoryStream msDecrypt = new MemoryStream(encrypted);
CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);
this.tbDecrypt.Text = ByteToString(csDecrypt);
catch (Exception ex)
this.tbEncrypt.Text = ex.Message.ToString();