Requested registry access is not allowed

Imports Microsoft.Win32


Public Class RegistryTrial
    Private Last, First, RemainsDays, RemainsDays1, strOldDay, strOldMonth, strOldYear As String
    'Number of Days Of the trial version. 
    Private mintSystem_UsedTrialDays As Integer 'Number of days system used 
    Public StartDate As String
    Public LastDate As String
    Public FinalDate, FinalDateTime As String
    Private WebPage_Page As Web.AspNetHostingPermission

    Public Function Regedit(ByVal TrialPeriod As Integer) As String

        'It first create Key then Stored value in it  
        Dim regKey As RegistryKey
        Try
            Dim strRet As String = "0"
            regKey = Registry.LocalMachine.OpenSubKey("SOFTWARE", True)
            regKey = Registry.LocalMachine.OpenSubKey("Software\AppSecurity", True)

            If regKey Is Nothing Then
                regKey = Registry.LocalMachine.OpenSubKey("SOFTWARE", True)
                regKey.CreateSubKey("AppSecurity")
                regKey.Close()
                If WriteValue(TrialPeriod) = False Then
                    Return "setting fail."
                End If
            Else
                strRet = GetValueFromReg(TrialPeriod)
                Return strRet
            End If
        Catch ex As Exception
            Return ""
        End Try
    End Function

    Public Function GetValueFromReg(ByVal mintTrialPeriod As Integer) As String
        'This Function is used to Get/Read The Value from the registry 
        Dim strReturn As String = ""
        Dim regKey As RegistryKey
        Dim ver, Final As String
        regKey = Registry.LocalMachine.OpenSubKey("Software\AppSecurity", True) 'its opens the path to read value 
        ver = regKey.GetValue("System_In") 'System_In=It get the value in (StartDate) & ";" & (LastDate) which is already stored in Encrypted formate. 

        If ver = "" Then 'If User Change It 
            Return "You have change some module,you are un-authorised to use the application."
        Else
            Final = funcDecrpt_Date(ver) 'this Decrypt the Value 
            If Final.Length() = "21" Then
                Last = Final.Substring(11)
                strOldDay = Final.Substring(0, 2) 'It Display Day ex:"01" 
                strOldMonth = Final.Substring(3, 2) 'It Display Month ex:"01" 
                strOldYear = Final.Substring(6, 4) 'It Display Year ex:"2009" 
                First = Final.Substring(0, 10) 'It Display startdate from Registry 

                RemainsDays = DisplayApplicationStatus(DiffDate(strOldDay, strOldMonth, strOldYear), mintTrialPeriod)
                mintSystem_UsedTrialDays = DiffDate(strOldDay, strOldMonth, strOldYear)
                Dim todaydate As String
                todaydate = Format(Today, "dd/MM/yyyy")
                'it Comapairs the LastDate Stored in Registry with Todaysdate 
                If RemainsDays1 = 0 Then
                    Return "Sorry,Your trial period is over!!Please purchase this software."
                Else
                    Dim LastMonth As String
                    Dim CurrentMonth As String
                    LastMonth = Last.Substring(3, 2)
                    CurrentMonth = todaydate.Substring(3, 2)
                    If LastMonth > CurrentMonth Then
                        If Last = todaydate Or First > todaydate Then
                            Return "Sorry,Your trial period is over!!Please purchase this software."
                        Else
                            strReturn = GetLastAccessDateTime()
                            If strReturn <> "LogIn" Then
                                Return strReturn
                            Else
                                If RemainsDays1 = Nothing Then
                                    Return "123Today is your last day in your free trial period."
                                Else
                                    Return "123You have " & RemainsDays1 & " days remaining in your free trial period."
                                End If
                            End If
                        End If
                    Else
                        If Last = todaydate Or Last < todaydate Or First > todaydate Then
                            Return "Sorry,Your trial period is over!!Please purchase this software."
                        Else
                            strReturn = GetLastAccessDateTime()
                            If strReturn <> "LogIn" Then
                                Return strReturn
                            Else
                                If RemainsDays1 = Nothing Then
                                    Return "123Today is your last day in your free trial period."
                                Else
                                    Return "123You have " & RemainsDays1 & " days remaining in your free trial period."
                                End If
                            End If
                        End If
                    End If
                End If
            Else
                Return "You have change some module,you are un-authorised to use the application."
            End If
        End If
    End Function

    Public Function funcEncrpt_Date(ByVal mDate As String) As String
        'This function used to stored dates in the Encrypted Formate in the Registry 
        Dim intI As Integer = 0
        Dim mstrDate As String = ""
        Try
            For intI = 1 To Len(mDate)
                If Mid(Trim(mDate), intI, 1) = "1" Then
                    mstrDate = mstrDate & ChrW(Asc(Mid(Trim(mDate), intI, 1)) - 5)
                Else
                    mstrDate = mstrDate & ChrW(Asc(Mid(Trim(mDate), intI, 1)) - 10)
                End If
            Next
            If InStr(mstrDate, "'") <> 0 Then
                mstrDate = mstrDate & "'"
            End If
        Catch ex As Exception
        End Try
        Return mstrDate
    End Function

    Public Function funcDecrpt_Date(ByVal mDate As String) As String
        'This Decrypts the dates which is stored in the registry in Encrypted Formate and used in the application 
        Dim intI As Integer = 0
        Dim mstrDate As String = ""
        Try
            For intI = 1 To Len(mDate)
                If Mid(Trim(mDate), intI, 1) = "," Then
                    mstrDate = mstrDate & ChrW(Asc(Mid(Trim(mDate), intI, 1)) + 5)
                Else
                    mstrDate = mstrDate & ChrW(Asc(Mid(Trim(mDate), intI, 1)) + 10)
                End If
            Next
        Catch ex As Exception
        End Try
        Return mstrDate
    End Function

    Public Function WriteValue(ByVal TrialPeriod As Integer) As Boolean
        'This Function Writes The value in thw registry 
        Dim regKey As RegistryKey
        Dim SaveFirstAccessdate As String
        Try
            regKey = Registry.LocalMachine.OpenSubKey("Software\AppSecurity", True)
            StartDate = Format(Today, "dd/MM/yyyy")
            LastDate = Format(Today.AddDays(TrialPeriod), "dd/MM/yyyy")
            FinalDate = funcEncrpt_Date(StartDate) & ";" & funcEncrpt_Date(LastDate)
            regKey.SetValue("System_In", FinalDate) 'This write StartDate and Lastdate In the Registry 
            SaveFirstAccessdate = Format(Today, "dd/MM/yyyy") & ";" & Format(TimeOfDay, "hh:mm:ss tt")
            regKey.SetValue("System_Used", funcEncrpt_Date(SaveFirstAccessdate)) 'This write Last used system DATE;TIME In the Registry 
            regKey.SetValue("AppName", "AppSecurity") 'This write Application Name in Registry  
            regKey.Close()
            Return True
        Catch ex As Exception
            Return False
        End Try
    End Function
    Public Function GetLastAccessDateTime() As String
        'This function is used to get value from registry (Last used DateTime) 
        Try
            Dim regKey As RegistryKey
            regKey = Registry.LocalMachine.OpenSubKey("SOFTWARE", True)
            Dim LastAccess As String
            regKey = Registry.LocalMachine.OpenSubKey("Software\AppSecurity", True)
            LastAccess = regKey.GetValue("System_Used") ', funcDecrpt_Date(FinalDateTime)) 
            If LastAccess = "" Or LastAccess.Length <> "22" Then
                Return "You have change some module,you are un-authorised to use the application."
            Else
                Dim TodayDate As String
                TodayDate = (Format(Today, "dd/MM/yyyy") & ";" & Format(TimeOfDay, "hh:mm:ss tt"))
                If TodayDate < funcDecrpt_Date(LastAccess) Then
                    Return "You have change your system Date mannually,you are un-authorised to use the application."
                Else
                    Return "LogIn"
                End If
            End If
            regKey.Close()
        Catch ex As Exception
            Return ""
        End Try
    End Function
    Public Sub SaveLastAceessDateTime()
        'this function used on the form exit ,to save Last Used System DateTime 
        Try
            Dim regKey As RegistryKey
            regKey = Registry.LocalMachine.OpenSubKey("SOFTWARE", True)
            Dim SaveLastAccessdate As String
            regKey = Registry.LocalMachine.OpenSubKey("Software\AppSecurity", True)
            SaveLastAccessdate = Format(Today, "dd/MM/yyyy") & ";" & Format(TimeOfDay, "hh:mm:ss tt")
            FinalDateTime = funcEncrpt_Date(SaveLastAccessdate)
            regKey.SetValue("System_Used", FinalDateTime)
            regKey.Close()
        Catch ex As Exception

        End Try
    End Sub

    Public Function DisplayApplicationStatus(ByVal pDaysSystem_Used As Integer, ByVal pTotalDays As Integer) As String
        'Check if the author made the mistake of setting the trial period days to less than 0 
        If pTotalDays < 0 Then
            Return "An error has occurred! The author has alloted you a trial period less than zero days, which is impossible. Please contact the author and tell him/her of this error."
        End If

        'Check if the trial is expired 
        If pDaysSystem_Used >= pTotalDays Then
            Return "Your trial has expired!"
        End If

        'Draw the bar 
        RemainsDays1 = pTotalDays - pDaysSystem_Used
        Return "You have " + (pTotalDays - pDaysSystem_Used).ToString + " days remaining in your free trial period."
    End Function

    Public Function DiffDate(ByVal OrigDay As String, ByVal OrigMonth As String, ByVal OrigYear As String) As Integer
        Try
            Dim D1 As Date = New Date(Convert.ToInt32(OrigYear), Convert.ToInt32(OrigMonth), Convert.ToInt32(OrigDay))
            Return Convert.ToInt32(DateDiff(DateInterval.Day, D1, DateTime.Now))
        Catch
            Return 0
        End Try
    End Function

    Private Sub Btnclose_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btnclose.Click
        If MessageBox.Show("Are you sure,you want to Exit application.", "Exit", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
            Dim obj As New RegistryTrial
            obj.SaveLastAceessDateTime()
            Me.Close()
        Else
            Me.Show()
        End If
    End Sub


    Private Sub RegistryTrial_Load_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim obj As New RegistryTrial
        'The following code is used to operate Trial Version DLL 
        Dim str As String = obj.Regedit(1830) 'no of trial days

        If str = Nothing Then
            Me.Close()
        Else
            If str.StartsWith("123") = True Then
                MsgBox(str.Substring(3), MsgBoxStyle.Information, "Information")
                If Me.MdiChildren.Length > 0 Then
                    Exit Sub
                End If

            Else
                MsgBox(str, MsgBoxStyle.Critical, "Error")
                End
            End If
        End If
    End Sub
End Class