private void CalculateTokenVector()
{
Key = MD5Helper.Hash(Token);
// Join MD5 of key and the token itself to get the vector
var ivContent = ByteList.Join(Key, Token);
InitializationVector = MD5Helper.Hash(ivContent.ToArray());
}
internal byte[] GetPayloadBytes()
{
if (_token == null)
{
throw new Exception("Token is missing");
}
if (_deviceId == null)
{
throw new Exception("DeviceID is missing");
}
// Encrypt the payload using the token
var jsonBody = CreateJson();
var encryptedPayload = AESHelper.Encrypt(_token.Key, _token.InitializationVector, jsonBody);
using (var content = new ByteList())
{
// Create the header
content.Add(0x21, 0x31); // Magic number
content.WriteUInt16BE(32 + encryptedPayload.Length); // Content+header length
content.Repeat(0x00, 4); // Unknown1
content.AddRange(_deviceId); // Device ID (received from handshake)
// Add seconds passed to server timestamp
var secondsPassed = (DateTime.Now - _serverStamp.ReceivedTime).TotalSeconds;
// Write Stamp to payload
content.WriteUInt32BE((UInt32)Math.Floor(_serverStamp.Timestamp + secondsPassed));
// Header is done and we have the payload and the token. We can now write the MD5 checksum
// Get MD5 checksum of [header, token payload]
content.AddRange(ByteList.Join(content.Take(16).ToArray(), _token.Token, encryptedPayload).ToMd5());
// Then add the encrypted payload itself
content.AddRange(encryptedPayload);
return(content.ToBinaryASCIIArray());
}
}