Microsoft.Protocols.TestTools.StackSdk.RemoteDesktop.Rdpbcgr.RdpbcgrDecoder.DecodeTsFpUpdatePDU C# (CSharp) Method

        public StackPacket DecodeTsFpUpdatePDU(byte[] data)
        {
            // initialize
            int currentIndex = 0;
            TS_FP_UPDATE_PDU pdu = new TS_FP_UPDATE_PDU();

            // TS_FP_UPDATE_PDU: fpOutputHeader
            pdu.fpOutputHeader = ParseByte(data, ref currentIndex);

            // Get infomation from fpOutputHeader
            nested_TS_FP_UPDATE_PDU_fpOutputHeader_actionCode_Values actionCode;
            encryptionFlagsChgd_Values encryptionFlags;
            GetFpOutputHeaderInfo(pdu.fpOutputHeader, out actionCode, out encryptionFlags);

            // TS_FP_UPDATE_PDU: length1
            pdu.length1 = ParseByte(data, ref currentIndex);

            // TS_FP_UPDATE_PDU: length2 (optional)
            if ((ConstValue.MOST_SIGNIFICANT_BIT_FILTER & pdu.length1) != pdu.length1)
            {
                // length2 is present (since the most significant bit of length1 is set)
                pdu.length2 = ParseByte(data, ref currentIndex);
            }

            // TS_FP_UPDATE_PDU: fipsInformation
            if (EncryptionLevel.ENCRYPTION_LEVEL_FIPS == clientContext.RdpEncryptionLevel)
            {
                pdu.fipsInformation = ParseTsFpFipsInfo(data, ref currentIndex);
            }

            // TS_FP_UPDATE_PDU: dataSignature
            if (IsFlagExist((byte)encryptionFlags, (byte)encryptionFlagsChgd_Values.FASTPATH_OUTPUT_ENCRYPTED))
            {
                // pdu were encrypted, data signature exists
                pdu.dataSignature = GetBytes(data, ref currentIndex,
                    ConstValue.TS_FP_UPDATE_PDU_DATA_SIGNATURE_LENGTH);
            }
            else
            {
                pdu.dataSignature = null;
            }

            // Decryption
            bool isSalted = IsFlagExist((byte)encryptionFlags,
                (byte)encryptionFlagsChgd_Values.FASTPATH_OUTPUT_SECURE_CHECKSUM);
            byte[] remainData = GetBytes(data, ref currentIndex, (data.Length - currentIndex));
            byte[] decryptedData = DecryptFastPathUpdateData(remainData, pdu.dataSignature, isSalted);

            // Decrypted data index
            int decryptedDataIndex = 0;

            // TS_FP_UPDATE_PDU: fpOutputUpdates
            pdu.fpOutputUpdates = ParseTsFpUpdates(decryptedData, ref decryptedDataIndex);

            // Check if data length exceeded expectation
            VerifyDataLength(decryptedData.Length, decryptedDataIndex, ConstValue.ERROR_MESSAGE_DATA_LENGTH_EXCEEDED);
            return pdu;
        }