public static byte[] Encrypt(byte[] input, uint ms)
{
var ct = new CipherText(input, ms);
var iv = Cipher8FromRand(ref ms);
//encrypt
foreach (var bytes in ct.Content)
{
for (var j = 0; j < 256; j++)
{
bytes[j] ^= iv[j];
}
var temp2 = new uint[0x100 / 4];
Buffer.BlockCopy(bytes, 0, temp2, 0, 0x100);
ShufflesLegacy.Shuffle2(temp2);
Buffer.BlockCopy(temp2, 0, iv, 0, 0x100);
Buffer.BlockCopy(temp2, 0, bytes, 0, 0x100);
}
return(ct.GetBytes(ref ms));
}
//this returns an empty buffer if error
public static byte[] Decrypt(byte[] input, out int length)
{
int version, len = input.Length;
if (len < 261)
{
length = 0;
return(new byte[] { });
}
var modSize = len % 256;
switch (modSize)
{
case 32:
version = 1;
break;
case 33:
version = 2;
break;
case 5:
version = 3;
break;
default:
length = 0; return(new byte[] { });
}
byte[] cipher8, output;
int outputLen;
switch (version)
{
case 1:
outputLen = len - 32;
output = new byte[outputLen];
Buffer.BlockCopy(input, 32, output, 0, outputLen);
cipher8 = Cipher8FromIv(input);
break;
case 2:
outputLen = len - 33;
output = new byte[outputLen];
Buffer.BlockCopy(input, 32, output, 0, outputLen);
cipher8 = Cipher8FromIv(input);
break;
default:
outputLen = len - 5;
output = new byte[outputLen];
Buffer.BlockCopy(input, 4, output, 0, outputLen);
var tmp = new byte[4];
Buffer.BlockCopy(input, 0, tmp, 0, 4);
Array.Reverse(tmp);
var ms = BitConverter.ToUInt32(tmp, 0);
cipher8 = Cipher8FromRand(ref ms);
if (input[len - 1] != MakeIntegrityByte(GenerateRand(ref ms)))
{
length = 0; return(new byte[] { });
}
break;
}
var outputcontent = new Collection <byte[]>();
//break into chunks of 256
var roundedsize = (outputLen + 255) / 256; //round up
for (var i = 0; i < roundedsize; i++)
{
outputcontent.Add(new byte[256]);
}
for (var i = 0; i < outputLen; i++)
{
outputcontent[i / 256][i % 256] = output[i];
}
foreach (var bytes in outputcontent)
{
var temp2 = new uint[0x100 / 4];
var temp3 = new uint[0x100 / 4];
Buffer.BlockCopy(bytes, 0, temp2, 0, 0x100);
Buffer.BlockCopy(temp2, 0, temp3, 0, 0x100);
if (version == 1)
{
ShufflesLegacy.Unshuffle(temp2);
}
else
{
ShufflesLegacy.Unshuffle2(temp2);
}
Buffer.BlockCopy(temp2, 0, bytes, 0, 0x100);
for (var j = 0; j < 256; j++)
{
bytes[j] ^= cipher8[j];
}
Buffer.BlockCopy(temp3, 0, cipher8, 0, 0x100);
}
var ret = new byte[outputLen];
for (var i = 0; i < outputcontent.Count; i++)
{
Buffer.BlockCopy(outputcontent[i], 0, ret, i * 256, 0x100);
}
length = outputLen - ret.Last();
return(ret);
}
