Prevent the macro break for pass-protected self-destructing file - excel

Question

I've decided to create a pass-protected file which will self-destruct after three wrong password entries. The macro runs with the file open (UserForm with pass entry field pops up) but the weak point is that Ctrl-Break allows to stop the macro and get access to the code.
Is there any way to disable/prevent Break option in a particular workbook (via VBA, preferably)?
If you are interested, I can provide the macro upon request.
UPD: Here's the macro i'm using (Date based).
Private Sub Workbook_Open()
If Date > Cdate("30/03/2015") Then
WARNING.Show
End If
End Sub
This part of code is assigned to "Ok" and "Cancel" buttons of the UserForm "WARNING".
Public i As Integer
Public b As Integer
Sub setib()
i = 2 - b
b = b + 0
End Sub
Private Sub CnclBtn_Click()
WARNING.Hide
With ThisWorkbook
.Saved = True
.Close False
End With
End Sub
Private Sub OKBtn_Click()
Call setib
Dim Pass As String: Pass = "*your pass*"
Dim PassInput As String: PassInput = WARNING.PassField.Text
If PassInput = Pass Then
MsgBox "Password is correct"
GoTo Safe:
Else
If b < 2 Then
MsgBox "Password is incorrect. " & i & " attempts left."
Else
MsgBox "No More attempts"
End If
If b = 2 Then
WARNING.Hide
GoTo Destroy:
Else
WARNING.PassField.Value = vbNullString
WARNING.PassField.SetFocus
b = b + 1
GoTo EndSub:
End If
End If
Safe:
ActiveWorkbook.VBProject.VBComponents("ThisWorkbook").CodeModule.DeleteLines 1, _
ActiveWorkbook.VBProject.VBComponents("ThisWorkbook").CodeModule.CountOfLines
WARNING.Hide
GoTo EndSub:
Destroy:
With ThisWorkbook
.Saved = True
.ChangeFileAccess xlReadOnly
Kill .FullName
.Close False
End With
EndSub:
Sheet1.Activate
End Sub

Answer 1

You could simply password-protect the VBA project. That will avoid the need to worry about playing with the Application-level settings for EnableCancelKey.
While the user may be able to "break" with the cancel key, they will not be able to view the code without supplying the proper password for the VBA project.
With the VBAProject protected, the user can "break" execution of the code, the user should not be able to enter "break mode", and the Excel application will not be interactive (so the user will not be able to access the worksheets). At this point, the User Form will be frozen on the screen and the application unresponsive. The user then has two options that I can see:
If they know the name of the userform, they could conceivably Unload UserForm1 from the Immediate window in the VBE. So, you should pick some name for the UserForm which they will not likely guess. If they do this, they will be able to access the file itself, but if you give the UF a secure name, they'll never guess it correctly.
Otherwise, they're SOL, unless they Ctrl+AltDel, and kill the Excel application procdess.
NOTE: Excel passwords, whether on the worksheets or the VBAProject (or both) can be cracked by anyone intent on doing so, and are only a good measure to prevent inadvertent corruption or manipulation of the data.