byte[] ConvertToEncryptedMessage(NewCamdMessage message)
{
_logger.Debug($"Prepare message headers for {Name}");
var prepareData = new List <byte>();
prepareData.Add((byte)(message.MessageId >> 8));
prepareData.Add((byte)(message.MessageId & 0xFF));
prepareData.Add((byte)(message.ServiceId >> 8));
prepareData.Add((byte)(message.ServiceId & 0xFF));
prepareData.Add((byte)(message.ProviderId >> 16));
prepareData.Add((byte)((message.ProviderId >> 8) & 0xFF));
prepareData.Add((byte)(message.ProviderId & 0xFF));
prepareData.Add(0);
prepareData.Add(0);
prepareData.Add(0);
_logger.Debug($"Correct message headers for {Name}");
message.Data[0] = (byte)message.Type;
message.Data[1] = (byte)((message.Data[1] & 240) | (((message.Data.Length - 3) >> 8) & 255));
message.Data[2] = (byte)((message.Data.Length - 3) & 255);
_logger.Debug($"Copy {message.Data.Length} bytes into the buffer for {Name}");
prepareData.AddRange(message.Data);
//Fill up
while (prepareData.Count % 8 != 7)
{
prepareData.Add(0);
}
_logger.Debug($"Encrypt data before sending to {Name}");
var padding = new byte[8];
_random.NextBytes(padding);
//fill up bytes with padding data at the end
var bufferLen = prepareData.Count;
var paddingLen = (8 - ((bufferLen - 2) % 8)) % 8;
var prepareDataArray = prepareData.ToArray();
Buffer.BlockCopy(padding, 0, prepareDataArray, bufferLen - paddingLen, paddingLen);
prepareData = prepareDataArray.ToList();
//Add checksum
prepareData.Add(XorSum(prepareData.ToArray()));
var ivec = new byte[8];
_random.NextBytes(ivec);
var dataToEncrypt = prepareData.ToArray();
var encrypted = _crypto.Encrypt(dataToEncrypt, _keyblock, ivec).ToList();
var dataToSend = new List <byte>();
dataToSend.Add((byte)((encrypted.Count + ivec.Length) >> 8));
dataToSend.Add((byte)((encrypted.Count + ivec.Length) & 0xFF));
dataToSend.AddRange(encrypted);
dataToSend.AddRange(ivec);
return(dataToSend.ToArray());
}
public void SendMessage(string logMessage, NewCamdMessage message)
{
var log = $"{logMessage}: {message.Type}";
var data = ConvertToEncryptedMessage(message);
SendMessage(log, data);
}
NewCamdMessage ParseMessage(byte[] buffer)
{
_logger.Debug("Read TripleDES Initialization Vector from encrypted message");
var ivec = buffer.Skip(buffer.Length - 8).Take(8).ToArray();
_logger.Debug("Decrypt the rest of the message");
var decryptedData = _crypto.Decrypt(buffer, buffer.Length - 8, _keyblock, ivec);
_logger.Debug("Parse decrypted message");
var len = (((decryptedData[3 + NewCamdMessage.HeaderLength] << 8) | decryptedData[4 + NewCamdMessage.HeaderLength]) & 0x0FFF) + 3;
if (len > decryptedData.Length)
{
throw new InvalidNewcamdMessage($"Decryption of the message from {Name} failed");
}
var retValue = new NewCamdMessage
{
MessageId = ((decryptedData[0] << 8) | decryptedData[1]) & 0xFFFF,
ServiceId = ((decryptedData[2] << 8) | decryptedData[3]) & 0xFFFF,
ProviderId = decryptedData[4] << 16 | decryptedData[5] << 8 | decryptedData[6],
Data = decryptedData.Skip(2 + NewCamdMessage.HeaderLength).Take(len).ToArray(),
Type = (NewCamdMessageType)decryptedData[2 + NewCamdMessage.HeaderLength]
};
_logger.Debug($"Received decrypted message msgid: {retValue.MessageId}, serviceid: {retValue.ServiceId}, providerid: {retValue.ProviderId}, length: {len}, type {retValue.Type} from {Name}");
return(retValue);
}
void ReceiveMessage(NewCamdMessage message)
{
if (message == null)
{
return;
}
_logger.Debug($"Handle message: {message.Type} from {Name}");
switch (message.Type)
{
case NewCamdMessageType.MsgClient2ServerLogin:
Login(message);
break;
case NewCamdMessageType.MsgCardDataReq:
CardData(message);
break;
case NewCamdMessageType.MsgKeepalive:
_logger.Debug($"{Name} - Keep connection alive");
_communication.SendMessage("Keep alive", message);
break;
case NewCamdMessageType.MsgKeyblockReq1:
case NewCamdMessageType.MsgKeyblockReq2:
KeyBlock(message);
break;
default:
_logger.Error($"Unable to handle {message.Type}");
Dispose();
break;
}
}
void Login(NewCamdMessage message)
{
string username;
string encryptedPassword;
try
{
const int header = 3;
var splitter = Array.IndexOf(message.Data, (byte)0, header);
username = Encoding.ASCII.GetString(message.Data.Skip(header).Take(splitter - header).ToArray());
splitter++;
encryptedPassword = Encoding.ASCII.GetString(message.Data.Skip(splitter).Take(message.Data.Length - splitter - 1).ToArray());
}
catch (Exception ex)
{
_logger.Warn($"Couldn't read the login credentials from {Name}");
_logger.Debug("Exception at login", ex);
Dispose();
return;
}
var expectedPassword = _crypto.UnixEncrypt(_settings.Password, "$1$abcdefgh$");
var loginValid = _settings.Username.Equals(username) && expectedPassword.Equals(encryptedPassword);
message.Type = loginValid ? NewCamdMessageType.MsgClient2ServerLoginAck : NewCamdMessageType.MsgClient2ServerLoginNak;
_logger.Info($"{Name} - Login is {message.Type}");
message.Data = new byte[3];
_communication.SendMessage("Login response", message);
if (!loginValid)
{
return;
}
_communication.UpdateKeyBlock(encryptedPassword);
}
void KeyBlock(NewCamdMessage message)
{
_logger.Info($"{Name} - Give keyblock info");
var header = new byte[] { (byte)message.Type, 1, 1 };
var keyInfo = _keyblock.DecryptBlock(message.Type, message.Data);
message.Data = header.Concat(keyInfo).ToArray();
_communication.SendMessage("Key info", message);
}
void CardData(NewCamdMessage message)
{
_logger.Info($"{Name} - Request card info");
message.Type = NewCamdMessageType.MsgCardData;
message.Data = new byte[26];
//Provide CAID
message.Data[4] = 0x56;
message.Data[5] = 0x01;
message.Data[14] = 1; //Set number of cards
message.Data[17] = 1; //Set provider ID of card 1
_communication.SendMessage("Card info", message);
}