Xxtea Encryption Algorithm

/*
* It should be noted that the encrypted byte array is not a string. Because the C # string is saved according to unicode encoding.
* To encrypt a string, use the getbytes method of system. Text. encoding. utf8 (or other encoders) to convert it into a byte array before encryption. The same is true for keys.
* The key length is 128 bits, that is, the byte array of 16 elements, but it can work normally if it is less than 16 bytes or more than 16 bytes,
* When the number of bytes is less than 16, it is automatically filled with 16 bytes by Zeros. elements after more than 16 bytes are ignored.
* Note that the encrypted content is also a byte array, but you cannot convert it to a string using system. Text. encoding. utf8. Otherwise, information will be lost.
* System. Text. Encoding encoder = system. Text. encoding. utf8;
* Byte [] DATA = xxtea. Encrypt (encoder. getbytes (textbox1.text), encoder. getbytes ("1234567890 abcdef "));
* Textbox2.text = system. Convert. tobase64string (data );
**/
Using system;

Class xxtea
{
Public static byte [] encrypt (byte [] data, byte [] key)
{
If (data. Length = 0)
{
Return data;
}
Return tobytearray (encrypt (touint32array (data, true), touint32array (Key, false), false );
}
Public static byte [] decrypt (byte [] data, byte [] key)
{
If (data. Length = 0)
{
Return data;
}
Return tobytearray (decrypt (touint32array (data, false), touint32array (Key, false), true );
}

Public static uint32 [] encrypt (uint32 [] V, uint32 [] K)
{
Int32 n = V. Length-1;
If (n <1)
{
Return V;
}
If (K. Length <4)
{
Uint32 [] Key = new uint32 [4];
K. copyto (Key, 0 );
K = key;
}
Uint32 z = V [N], y = V [0], Delta = 0x9e3779b9, sum = 0, E;
Int32 p, q = 6 + 52/(n + 1 );
While (Q --> 0)
{
Sum = unchecked (sum + delta );
E = sum> 2 & 3;
For (P = 0; P <n; P ++)
{
Y = V [p + 1];
Z = unchecked (V [p] + = (z> 5 ^ y <2) + (Y> 3 ^ z <4) ^ (sum ^ y) + (K [P & 3 ^ e] ^ z ));
}
Y = V [0];
Z = unchecked (V [N] + = (z> 5 ^ y <2) + (Y> 3 ^ z <4) ^ (sum ^ y) + (K [P & 3 ^ e] ^ z ));
}
Return V;
}
Public static uint32 [] decrypt (uint32 [] V, uint32 [] K)
{
Int32 n = V. Length-1;
If (n <1)
{
Return V;
}
If (K. Length <4)
{
Uint32 [] Key = new uint32 [4];
K. copyto (Key, 0 );
K = key;
}
Uint32 z = V [N], y = V [0], Delta = 0x9e3779b9, sum, E;
Int32 p, q = 6 + 52/(n + 1 );
Sum = unchecked (uint32) (Q * delta ));
While (sum! = 0)
{
E = sum> 2 & 3;
For (P = N; P> 0; p --)
{
Z = V [p-1];
Y = unchecked (V [p]-= (z> 5 ^ y <2) + (Y> 3 ^ z <4) ^ (sum ^ y) + (K [P & 3 ^ e] ^ z ));
}
Z = V [N];
Y = unchecked (V [0]-= (z> 5 ^ y <2) + (Y> 3 ^ z <4) ^ (sum ^ y) + (K [P & 3 ^ e] ^ z ));
Sum = unchecked (Sum-delta );
}
Return V;
}
Private Static uint32 [] touint32array (byte [] data, Boolean includelength)
{
Int32 n = (data. Length & 3) = 0 )? (Data. length> 2): (data. length> 2) + 1 ));
Uint32 [] result;
If (includelength)
{
Result = new uint32 [n + 1];
Result [N] = (uint32) data. length;
}
Else
{
Result = new uint32 [N];
}
N = data. length;
For (int32 I = 0; I <n; I ++)
{
Result [I> 2] | = (uint32) data [I] <(I & 3) <3 );
}
Return result;
}
Private Static byte [] tobytearray (uint32 [] data, Boolean includelength)
{
Int32 N;
If (includelength)
{
N = (int32) data [data. Length-1];
}
Else
{
N = data. Length <2;
}
Byte [] result = new byte [N];
For (int32 I = 0; I <n; I ++)
{
Result [I] = (byte) (data [I> 2]> (I & 3) <3 ));
}
Return result;
}
}

 

Call:

Public partial class form1: Form
{
Public form1 ()
{
Initializecomponent ();
}

Private void button#click (Object sender, eventargs E)
{
System. Text. Encoding encoder = system. Text. encoding. utf8;
Byte [] DATA = xxtea. Encrypt (encoder. getbytes (textbox1.text), encoder. getbytes ("1234567890 abcdef "));
Textbox2.text = system. Convert. tobase64string (data );
}

Private void button2_click (Object sender, eventargs E)
{
System. Text. Encoding encoder = system. Text. encoding. utf8;
Try
{
Textbox2.text = encoder. getstring (xxtea. decrypt (system. Convert. frombase64string (textbox1.text), encoder. getbytes ("1234567890 abcdef ")));
}
Catch (exception)
{
MessageBox. Show ("your input is incorrect! ");
}
}
}