/// <summary>
/// 패킷을 보낼 수 있도록 가공한다. (zlib 압축 데이터 여기서 생성)
/// </summary>
/// <param name="key">Encryption key</param>
/// <param name="hmacKey">HMAC generation key</param>
/// <param name="prefix">The 6 bytes between the packet size and the IV</param>
public void CompressAndAssemble(byte[] key, byte[] hmacKey, byte[] prefix, int count)
{
// 버퍼를 복구할 수 있도록.
_buffer_before_assemble = _buffer;
byte[] data = Compression.Compress(_buffer);
byte[] Op = BitConverter.GetBytes((short)Opcode);
byte[] Len = BitConverter.GetBytes((int)data.Length + 4); // 버퍼 + 압축내용
Array.Reverse(Op);
Array.Reverse(Len);
byte[] TempData;
TempData = BytesUtil.ConcatBytes(Op, Len);
TempData = BytesUtil.ConcatBytes(TempData, BitConverter.GetBytes((bool)true)); // 압축임
TempData = BytesUtil.ConcatBytes(TempData, BitConverter.GetBytes((int)_buffer.Length)); // 실제 크기
_buffer = BytesUtil.ConcatBytes(TempData, data);
byte[] IV = CryptoGenerators.GenerateIV();
byte[] dataToAssemble = BytesUtil.ConcatBytes(
BytesUtil.ConcatBytes(prefix, BitConverter.GetBytes(count)),
BytesUtil.ConcatBytes(IV, CryptoFunctions.EncryptPacket(_buffer, key, IV)));
_buffer = CryptoFunctions.ClearPacket(dataToAssemble, hmacKey);
}
/// <summary>
/// Receives the packet without size and HMAC hash and returns the packet ready to be sent
/// </summary>
/// <param name="data">Packet data (excluding the packet size and the HMAC hash)</param>
/// <param name="hmacKey">HMAC Key</param>
public static byte[] ClearPacket(byte[] data, byte[] hmacKey)
{
byte[] packetSize = new byte[2];
byte[] hmac = new byte[10];
packetSize = BitConverter.GetBytes((short)(2 + data.Length + 10));
hmac = CryptoGenerators.GenerateHmac(data, hmacKey);
// Concatenates size + (prefix + IV + encrypted data) + hmac, composing the assembled packet
return(BytesUtil.ConcatBytes(packetSize, BytesUtil.ConcatBytes(data, hmac)));
}
/// <summary>
/// Returns the compressed packet from the input data
/// </summary>
/// <param name="dataToCompress">Packet data to be compressed</param>
public static byte[] CompressPacket(byte[] dataToCompress)
{
using (MemoryStream memoryStream = new MemoryStream())
{
using (ZlibStream compressor =
new ZlibStream(memoryStream, CompressionMode.Compress, CompressionLevel.Level1))
{
compressor.Write(dataToCompress, 11, (dataToCompress.Length - 11));
}
return(BytesUtil.ConcatBytes(BytesUtil.ReadBytes(dataToCompress, 0, 11), memoryStream.ToArray()));
}
}
/// <summary>
/// Performs the data padding in the encryption process
/// </summary>
/// <param name="packetBuffer">Data to be encrypted</param>
private static void PadPacket(ref byte[] packetBuffer)
{
int paddingLength = 8 + ((8 - packetBuffer.Length % 8) % 8);
byte[] paddingBytes = new byte[paddingLength];
int i = 0;
while (i < (paddingLength - 1))
{
paddingBytes[i] = (byte)i;
i++;
}
paddingBytes[i] = (byte)(i - 1);
packetBuffer = BytesUtil.ConcatBytes(packetBuffer, paddingBytes);
}
/// <summary>
/// Gets the received packet data and returns the decrypted data
/// </summary>
/// <param name="packetBuffer">The packet data the way it was received</param>
/// <param name="key">DES Encryption Key</param>
/// <param name="IV">Initialization vector</param>
public static byte[] DecryptPacket(byte[] packetBuffer, byte[] key, bool isHaveLength = false)
{
if (!isHaveLength)
{
packetBuffer = BytesUtil.ConcatBytes(BitConverter.GetBytes((short)(2 + packetBuffer.Length)), packetBuffer);
}
byte[] IV = BytesUtil.ReadBytes(packetBuffer, 8, 8);
using (DESCryptoServiceProvider desProvider = new DESCryptoServiceProvider())
{
desProvider.Mode = CipherMode.CBC;
desProvider.Padding = PaddingMode.None;
using (ICryptoTransform decryptor = desProvider.CreateDecryptor(key, IV))
{
byte[] rawData = decryptor.TransformFinalBlock(packetBuffer, 16,
packetBuffer.Length - CryptoConstants.GC_HMAC_SIZE - 16);
return(rawData);
//return BytesUtil.ReadBytes(rawData, 0, (rawData.Length - (rawData[rawData.Length - 1] + 2)));
}
}
}
/// <summary>
/// Returns the uncompressed packet from the input data
/// </summary>
/// <param name="packetToUncompress">Packet data to be uncompressed</param>
/// <returns></returns>
public static byte[] UncompressPacket(byte[] packetToUncompress)
{
return(BytesUtil.ConcatBytes(
BytesUtil.ReadBytes(packetToUncompress, 0, 11),
ZlibStream.UncompressBuffer(BytesUtil.ReadBytes(packetToUncompress, 11, (packetToUncompress.Length - 11)))));
}