private static bool CRC_OK(string input_frame, bool DEBUG)
{
string lblCRC = input_frame.Substring(input_frame.Length - 4, 4);
//Si le CRC a été forcé à 0 (trame issu de flux WAN)
if (lblCRC == "0000")
{
if (DEBUG)
{
System.Console.WriteLine(Environment.NewLine + "CRC = 0000 -> Continue (the frame presumably comes from a WAN message with a CRC forced to 0000");
}
return(true);
}
//sinon on calcule le CRC et vérifie qu'il est OK avec celui de la trame
else
{
//calcul du CRC
string CRCinput = input_frame.Substring(0, input_frame.Length - 4);
byte[] CRCinputbytes = Hex2Bytes(CRCinput);
short CRCcomputed = CLibCRC.CalculateCRC16EN13757(CRCinputbytes);
string lblCRCcomputed = CRCcomputed.ToString("X2");
//vérification du CRC calculé et du CRC de la trame
if (lblCRCcomputed.ToString().ToUpper().PadLeft(4, '0') == lblCRC.ToString().ToUpper())
{
if (DEBUG)
{
System.Console.WriteLine(Environment.NewLine + "CRC OK" + " CRC computed = " + lblCRCcomputed + " CRC in frame = " + lblCRC);
}
return(true);
}
else
{
System.Console.WriteLine("Error CRC: CRC computed = " + lblCRCcomputed + " CRC in frame = " + lblCRC);
return(false);
}
}
}
private static void LANcipherV1(string[] args, bool DEBUG)
{
string lblCField = args[8];
string lblMField = args[5];
string lblAField = args[6];
string lblCIField = args[12]; //"B4"; imposée par la LAN
string lblL6Vers = args[2];
string lblL6Wts = "0"; //champs reserved du L6Ctrl fixé à 0
string lblL6KeySel = Convert.ToString(Convert.ToInt32(args[9], 10), 2).PadLeft(4, '0');
string lblL6Ctrl = Convert.ToInt32(lblL6Vers + lblL6Wts + lblL6KeySel, 2).ToString("X2");
string lblL6OprID = args[10];
string lblL6Cpt = args[7];
string lblL6App = args[11];
string l7 = args[3];
string lblL6HashKenc = "00000000"; //recalcule après
string lblL6Tstamp = args[13];
//string lblL6Tstamp = "0000"; //recalculé par le K
string lblL6HashKmac = "0000"; //recalculé par le K
string CRC = "0000"; //recalculé par le K
byte[] kencbytes = Hex2Bytes(args[4].Substring(0, 32));
byte[] kmacbytes = Hex2Bytes(args[14].Substring(0, 32));
//System.Console.WriteLine("l7: " + l7 + Environment.NewLine + "lblMField: " + lblMField + Environment.NewLine + "lblAField: " + lblAField + Environment.NewLine + "lblL6Cpt: " + lblL6Cpt + Environment.NewLine + "lblCField: " + lblCField + Environment.NewLine + "l7: " + l7 + Environment.NewLine);
//IV
string txtIV = (lblMField.ToString() + lblAField.ToString() + lblL6Cpt.ToString() + lblCField.ToString()).PadRight(32, '0');
if (DEBUG)
{
System.Console.WriteLine("computed IV: " + txtIV);
}
//chiffrement L7
byte[] l7cipheredbytes = CAES128.AES_CTR(Hex2Bytes(l7), kencbytes, Hex2Bytes(txtIV));
string l7ciphered = Bytes2Hex(l7cipheredbytes, l7cipheredbytes.Length);
if (DEBUG)
{
System.Console.WriteLine("LAN L7 ciphered: " + l7ciphered);
}
//L-field
Int32 lfield_calc = 1 + 2 + 6 + 1 + 1 + 1 + 2 + 1 + l7.Length / 2 + 4 + lblL6Tstamp.Length / 2 + 2 + 2; // longeur de la trame du C-field au CRC inclu
string lblLField = lfield_calc.ToString("X2");
//L6HashKenc
string block0Kenc = lblMField + lblAField + lblL6Cpt + "000000000000";
lblL6HashKenc = Bytes2Hex(CAES128.AES_CMAC(Hex2Bytes(block0Kenc + l7ciphered), kencbytes), 4);
if (DEBUG)
{
System.Console.WriteLine("lblL6HashKenc " + lblL6HashKenc);
}
//L6HashKmac
string HashKmacInput = lblL6Ctrl + lblL6OprID + lblL6Cpt + lblL6App + l7ciphered + lblL6HashKenc + lblL6Tstamp;
string block0Kmac = lblMField + lblAField + "0000000000000000";
string Cmacinput = block0Kmac + HashKmacInput;
if (DEBUG)
{
System.Console.WriteLine("full Cmacinput = " + Cmacinput);
}
byte[] Cmacinputbytes = Hex2Bytes(Cmacinput);
lblL6HashKmac = Bytes2Hex(CAES128.AES_CMAC(Cmacinputbytes, kmacbytes), 2);
if (DEBUG)
{
System.Console.WriteLine("lblL6HashKmac = " + lblL6HashKmac);
}
//CRC
string CRCinput = lblLField + lblCField + lblMField + lblAField + lblCIField + lblL6Ctrl + lblL6OprID + lblL6Cpt + lblL6App + l7ciphered + lblL6HashKenc + lblL6Tstamp + lblL6HashKmac;
byte[] CRCinputbytes = Hex2Bytes(CRCinput);
short CRCcomputed = CLibCRC.CalculateCRC16EN13757(CRCinputbytes);
CRC = CRCcomputed.ToString("X2");
if (DEBUG)
{
System.Console.WriteLine("CRC computed = " + CRC);
}
string L2 = lblLField + lblCField + lblMField + lblAField + lblCIField + lblL6Ctrl + lblL6OprID + lblL6Cpt + lblL6App + l7ciphered + lblL6HashKenc + lblL6Tstamp + lblL6HashKmac + CRC;
System.Console.WriteLine("L2 " + L2);
}