public override byte[] GetByteMessage()
{
List <byte> messageArray = new List <byte>();
messageArray.AddRange(Mhdr.ToArray());
messageArray.AddRange(AppEUI.ToArray());
messageArray.AddRange(DevEUI.ToArray());
messageArray.AddRange(DevNonce.ToArray());
if (!Mic.Span.IsEmpty)
{
messageArray.AddRange(Mic.ToArray());
}
return(messageArray.ToArray());
}
/// <summary>
/// A Method to calculate the Mic of the message
/// </summary>
/// <param name="nwskey">The Network Secret Key</param>
/// <returns> the Mic bytes</returns>
public byte[] CalculateMic(string appKey, byte[] algoinput)
{
IMac mac = MacUtilities.GetMac("AESCMAC");
KeyParameter key = new KeyParameter(ConversionHelper.StringToByteArray(appKey));
mac.Init(key);
byte[] rfu = new byte[1];
rfu[0] = 0x0;
byte[] msgLength = BitConverter.GetBytes(algoinput.Length);
byte[] result = new byte[16];
mac.BlockUpdate(algoinput, 0, algoinput.Length);
result = MacUtilities.DoFinal(mac);
Mic = result.Take(4).ToArray();
return(Mic.ToArray());
}
/// <summary>
/// Method to check if the mic is valid
/// </summary>
/// <param name="nwskey">the network security key</param>
/// <returns>if the Mic is valid or not</returns>
public override bool CheckMic(string nwskey)
{
IMac mac = MacUtilities.GetMac("AESCMAC");
KeyParameter key = new KeyParameter(ConversionHelper.StringToByteArray(nwskey));
mac.Init(key);
byte[] block =
{
0x49, 0x00, 0x00, 0x00, 0x00, (byte)Direction, (byte)DevAddr.Span[3], (byte)DevAddr.Span[2], (byte)DevAddr.Span[1],
(byte)DevAddr.Span[0], Fcnt.Span[0], Fcnt.Span[1], 0x00, 0x00, 0x00, (byte)(RawMessage.Length - 4)
};
var algoinput = block.Concat(RawMessage.Take(RawMessage.Length - 4)).ToArray();
byte[] result = new byte[16];
mac.BlockUpdate(algoinput, 0, algoinput.Length);
result = MacUtilities.DoFinal(mac);
return(Mic.ToArray().SequenceEqual(result.Take(4).ToArray()));
}
public override bool CheckMic(string appKey)
{
return(Mic.ToArray().SequenceEqual(PerformMic(appKey)));
}
public override byte[] PerformEncryption(string appSkey)
{
byte[] pt;
if (!CfList.Span.IsEmpty)
{
pt = AppNonce.ToArray().Concat(NetID.ToArray()).Concat(DevAddr.ToArray()).Concat(DlSettings.ToArray()).Concat(RxDelay.ToArray()).Concat(CfList.ToArray()).Concat(Mic.ToArray()).ToArray();
}
else
{
pt = AppNonce.ToArray().Concat(NetID.ToArray()).Concat(DevAddr.ToArray()).Concat(DlSettings.ToArray()).Concat(RxDelay.ToArray()).Concat(Mic.ToArray()).ToArray();
}
Aes aes = new AesManaged();
aes.Key = ConversionHelper.StringToByteArray(appSkey);
aes.IV = new byte[16];
aes.Mode = CipherMode.ECB;
aes.Padding = PaddingMode.None;
ICryptoTransform cipher;
cipher = aes.CreateDecryptor();
var encryptedPayload = cipher.TransformFinalBlock(pt, 0, pt.Length);
RawMessage = new byte[encryptedPayload.Length];
Array.Copy(encryptedPayload, 0, RawMessage, 0, encryptedPayload.Length);
return(encryptedPayload);
}