public void DecodeFromCBORObject(CBORObject obj)
{
if (obj.Count != 5)
{
throw new CoseException("Invalid MAC structure");
}
// Protected values.
if (obj[0].Type == CBORType.ByteString)
{
byte[] data = obj[0].GetByteString();
if (data.Length > 0)
{
objProtected = CBORObject.DecodeFromBytes(data);
if (objProtected.Type != CBORType.Map)
{
throw new CoseException("Invalid MAC Structure");
}
}
else
{
objProtected = CBORObject.NewMap();
}
}
else
{
throw new CoseException("Invalid MAC structure");
}
// Unprotected attributes
if (obj[1].Type == PeterO.Cbor.CBORType.Map)
{
objUnprotected = obj[1];
}
else
{
throw new CoseException("Invalid MAC Structure");
}
// Plain Text
if (obj[2].Type == CBORType.ByteString)
{
rgbContent = obj[2].GetByteString();
}
else if (!obj[2].IsNull) // Detached content - will need to get externally
{
throw new CoseException("Invalid MAC Structure");
}
// Authentication tag
if (obj[3].Type == CBORType.ByteString)
{
rgbTag = obj[3].GetByteString();
}
else
{
throw new CoseException("Invalid MAC Structure");
}
// Recipients
if (obj[4].Type == CBORType.Array)
{
// An array of recipients to be processed
for (int i = 0; i < obj[4].Count; i++)
{
Recipient recip = new Recipient();
recip.DecodeFromCBORObject(obj[4][i]);
recipientList.Add(recip);
}
}
else
{
throw new CoseException("Invalid MAC Structure");
}
}