public static void RC4Crypt(byte[] pachIn, int in_offset, byte[] pachOut, int out_offset, uint nLen, RC4Key key)
{
Debug.Assert(key != null && nLen > 0);
if (key == null)
{
return;
}
byte byX = key.byX;;
byte byY = key.byY;
byte[] pabyState = key.abyState;
byte byXorIndex;
for (uint i = 0; i < nLen; i++)
{
byX = Convert.ToByte(byX + 1);
byY = Convert.ToByte(pabyState[byX] + byY);
MpdUtilities.SwapByte(ref pabyState[byX], ref pabyState[byY]);
byXorIndex = Convert.ToByte(pabyState[byX] + pabyState[byY]);
if (pachIn != null)
{
pachOut[out_offset + i] = Convert.ToByte(pachIn[in_offset + i] ^ pabyState[byXorIndex]);
}
}
key.byX = byX;
key.byY = byY;
}
public static RC4Key RC4CreateKey(byte[] pachKeyData, uint nLen, ref RC4Key key, bool bSkipDiscard)
{
byte index1;
byte index2;
byte[] pabyState;
if (key == null)
{
key = new RC4Key();
}
pabyState = key.abyState;
for (int i = 0; i < 256; i++)
{
pabyState[i] = (byte)i;
}
key.byX = 0;
key.byY = 0;
index1 = 0;
index2 = 0;
for (int i = 0; i < 256; i++)
{
index2 = Convert.ToByte(pachKeyData[index1] + pabyState[i] + index2);
MpdUtilities.SwapByte(ref pabyState[i], ref pabyState[index2]);
index1 = (byte)((index1 + 1) % nLen);
}
if (!bSkipDiscard)
{
RC4Crypt(null, null, 1024, key);
}
return(key);
}