Devi crearti una classe che intercetta il popolamento delle celle e in quel preciso momento sostituire il valore con degli asterischi, naturalmente devi costruirti il datagrid a manina ed ereditare la DataGridTextBoxColumn
codice:
Public Class ColoredTextBoxColumn
Inherits DataGridTextBoxColumn
Public Sub New()
End Sub
Protected Overloads Overrides Sub Paint(ByVal graph As Graphics,ByVal rectbounds As Rectangle, ByVal curmngrSrc As _
CurrencyManager, ByVal RowNumber As Integer, ByVal _
ForeColorBrush As Brush, ByVal BackColorBrush As Brush, _
ByVal AlignmentRight As Boolean)
Dim o As Object
o = Me.GetColumnValueAtRow(curmngrSrc, RowNumber)
If Me.HeaderText = "Colonna che voglio nascondere" Then
If (Not (o) Is Nothing) Then
Dim cellValue As String
cellValue = CType(ObjVal, String).ToString
ecc...
ecc... qui va il tuo codice di sostituzione
MyBase.Paint(graph, rectbounds, curmngrSrc, RowNumber, _
' BackColorBrush, ForeColorBrush, AlignmentRight)
end sub
end class