Client Certificates at the Backend?

' Functions to provide encoding/decoding of strings with Base64.
' 
' Encoding: myEncodedString = base64_encode( inputString )
' Decoding: myDecodedString = base64_decode( encodedInputString )
'
' Programmed by Markus Hartsmar for ShameDesigns in 2002. 
' Email me at: mark@shamedesigns.com
' Visit our website at: http://www.shamedesigns.com/
'
Dim Base64Chars
Base64Chars =   "ABCDEFGHIJKLMNOPQRSTUVWXYZ" & _
      "abcdefghijklmnopqrstuvwxyz" & _
      "0123456789" & _
      "+/"
' Functions for encoding string to Base64
Public Function base64_encode( byVal strIn )
   Dim c1, c2, c3, w1, w2, w3, w4, n, strOut
   For n = 1 To Len( strIn ) Step 3
      c1 = Asc( Mid( strIn, n, 1 ) )
      c2 = Asc( Mid( strIn, n + 1, 1 ) + Chr(0) )
      c3 = Asc( Mid( strIn, n + 2, 1 ) + Chr(0) )
      w1 = Int( c1 / 4 ) : w2 = ( c1 And 3 ) * 16 + Int( c2 / 16 )
      If Len( strIn ) >= n + 1 Then 
         w3 = ( c2 And 15 ) * 4 + Int( c3 / 64 ) 
      Else 
         w3 = -1
      End If
      If Len( strIn ) >= n + 2 Then 
         w4 = c3 And 63 
      Else 
         w4 = -1
      End If
      strOut = strOut + mimeencode( w1 ) + mimeencode( w2 ) + _
              mimeencode( w3 ) + mimeencode( w4 )
   Next
   base64_encode = strOut
End Function
Private Function mimeencode( byVal intIn )
   If intIn >= 0 Then 
      mimeencode = Mid( Base64Chars, intIn + 1, 1 ) 
   Else 
      mimeencode = ""
   End If
End Function   
' Function to decode string from Base64
Public Function base64_decode( byVal strIn )
   Dim w1, w2, w3, w4, n, strOut
   For n = 1 To Len( strIn ) Step 4
      w1 = mimedecode( Mid( strIn, n, 1 ) )
      w2 = mimedecode( Mid( strIn, n + 1, 1 ) )
      w3 = mimedecode( Mid( strIn, n + 2, 1 ) )
      w4 = mimedecode( Mid( strIn, n + 3, 1 ) )
      If w2 >= 0 Then _
         strOut = strOut + _
            Chr( ( ( w1 * 4 + Int( w2 / 16 ) ) And 255 ) )
      If w3 >= 0 Then _
         strOut = strOut + _
            Chr( ( ( w2 * 16 + Int( w3 / 4 ) ) And 255 ) )
      If w4 >= 0 Then _
         strOut = strOut + _
            Chr( ( ( w3 * 64 + w4 ) And 255 ) )
   Next
   base64_decode = strOut
End Function
Private Function mimedecode( byVal strIn )
   If Len( strIn ) = 0 Then 
      mimedecode = -1 : Exit Function
   Else
      mimedecode = InStr( Base64Chars, strIn ) - 1
   End If
End Function