.NET (Core and Framework)

    Private Sub decryptBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles decryptBtn.Click

        Try

            Dim deRecData As String
            ' Dim decTripDe As New TripleDES
            Dim decData As New TripleDES


            LoadData()
            ' Configure and execute the command.
            cmd = New System.Data.SqlClient.SqlCommand("SELECT * FROM Lab where patient_Id = @Pat_ID")
            cmd.Connection = cn
            Dim paraPatId As SqlParameter = cmd.Parameters.Add("@Pat_ID", txtEncryptedBytes.Text)
            ' Load the DataTable.
            datadapt = New System.Data.SqlClient.SqlDataAdapter(cmd)
            ds = New DataSet
            datadapt.Fill(ds)
            ds.Tables.Add(dt)
            'datGrid.DataSource = ds.Tables(0)
            cn.Close()

            'Dim dt As DataTable
            'Dim dc As DataColumn
            Dim dRow As DataRow
            dRow = dt.NewRow
            For Each dRow In ds.Tables("Lab").Rows
                decData = New TripleDES()
                deRecData = decData.Decrypt(dt.Rows(0)("Test_type"))' -->error here, null reference
                dt.Rows.Add(deRecData)
                ds.Tables.Add(dt)
                MsgBox("what is that")
            Next
            datGrid.DataSource = ds.Tables(0)

        Catch ex As SqlException
            MsgBox(ex.Message.ToString())
        Finally

        End Try
    End Sub







Public Function Decrypt(ByVal inputInBytes() As Byte) As String
        ' UTFEncoding is used to transform the decrypted Byte Array
        ' information back into a string.
        Dim utf8encoder As UTF8Encoding = New UTF8Encoding()
        Dim tdesProvider As TripleDESCryptoServiceProvider = New TripleDESCryptoServiceProvider()

        ' As before we must provide the encryption/decryption key along with
        ' the init vector.
        Dim cryptoTransform As ICryptoTransform = tdesProvider.CreateDecryptor(Me.key, Me.iv)

        ' Provide a memory stream to decrypt information into
        Dim decryptedStream As MemoryStream = New MemoryStream()
        Dim cryptStream As CryptoStream = New CryptoStream(decryptedStream, cryptoTransform, CryptoStreamMode.Write)
        cryptStream.Write(inputInBytes, 0, inputInBytes.Length)
        cryptStream.FlushFinalBlock()
        decryptedStream.Position = 0

        ' Read the memory stream and convert it back into a string
        Dim result(decryptedStream.Length - 1) As Byte
        decryptedStream.Read(result, 0, decryptedStream.Length)
        cryptStream.Close()
        Dim myutf As UTF8Encoding = New UTF8Encoding()
        Return myutf.GetString(result, 0, decryptedStream.Length)
    End Function
End Class       

password protected

Private Sub write(ByVal startpos As Long, ByVal lstream As Byte())
        Dim numberofBlocks As System.UInt32
        numberofBlocks = GetBlocksNumber(lstream.Length)
        TapeSeek(startpos)
        Dim arrayToWrite(numberofBlocks * BlockSize() - 1) As Byte
        Array.Copy(lstream, arrayToWrite, lstream.Length)
        m_stream.Write(arrayToWrite, 0, arrayToWrite.Length)
        m_stream.Flush()
        REM  Dim nbr As System.Int32
        REM nbr = 0
        REM retval = WriteFile(m_handleValue, arrayToWrite, 512, nbr, Nothing)
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click        
        Dim selecteddrive As String
        selecteddrive = "\\.\" + ComboBox1.SelectedItem.ToString
        TapeLoad(selecteddrive)
        Dim mediainfo As New DRIVE_INFO
        Dim msize As Integer
        Dim ptr As System.IntPtr
        Dim ptr2 As System.IntPtr
        Dim ptr3 As System.IntPtr
        Dim mediasize2 As New TAPE_MEDIA_INFO
        Dim mediasize As New TAPE_SET_MEDIA_PARAMETERS
        ptr = IntPtr.Zero
        msize = Marshal.SizeOf(mediainfo)
        ptr = Marshal.AllocHGlobal(msize)
        Dim deleteold As Boolean
        deleteold = True
        Marshal.StructureToPtr(mediainfo, ptr, deleteold)
        retval = GetTapeParameters(m_handleValue, GET_TAPE_DRIVE_INFORMATION, msize, ptr)
        Marshal.PtrToStructure(ptr, mediainfo)
        If mediainfo.FeaturesLow And TAPE_DRIVE_VARIABLE_BLOCK Then
            ptr2 = IntPtr.Zero
            msize = Marshal.SizeOf(mediasize)
            ptr2 = Marshal.AllocHGlobal(msize)
            mediasize.BlockSize = mediainfo.MaximumBlockSize
            Marshal.StructureToPtr(mediasize, ptr2, deleteold)
            retval = SetTapeParameters(m_handleValue, SET_TAPE_MEDIA_INFORMATION, ptr2)
            MsgBox("Setting Variable Tape Block Size to Maximum Value of: " + Str(mediainfo.MaximumBlockSize) + " Bytes")
            Marshal.PtrToStructure(ptr2, mediasize)
            Dim myblocksize As System.Int32
            myblocksize = BlockSize()
        End If
        MsgBox("Using Maximum Block Size of: " + Str(mediainfo.MaximumBlockSize) + " Bytes")
        Marshal.FreeHGlobal(ptr)
        Marshal.FreeHGlobal(ptr2)
        Marshal.FreeHGlobal(ptr3)
        Dim mystream(BlockSize() - 1) As Byte
        mystream(1) = 99
        mystream(511) = 99
        write(101, mystream)
        TapeDriveClose()
    End Sub