regex - Excel VBA 使用正则表达式查找和屏蔽 PAN 数据以实现 PCI DSS 合规性

Question

由于在文件系统中发现信用卡数据的大多数工具不再列出可疑文件，因此需要工具来屏蔽必须保留的文件中的任何数据。

对于可能存在大量信用卡数据的 excel 文件，我认为使用正则表达式检测所选列/行中的信用卡数据并将中间 6-8 位数字替换为 Xs 的宏对许多人来说很有用。可悲的是，我不是正则表达式宏领域的专家。

下面基本上只适用于 3 个卡品牌的正则表达式，如果 PAN 位于具有其他数据的单元格中(例如评论字段)，则适用

下面的代码有效，但可以改进。改进正则表达式以使其适用于更多/所有卡品牌并通过包含 LUHN 算法检查来减少误报会很好。

剩余的改进/问题:

将所有卡品牌的 PAN 与扩展的正则表达式匹配

包括 Luhn 算法检查(已修复 - 好主意 Ron)

改进 Do While 逻辑(由 stribizhev 修复)

更好地处理不含 PAN 的单元格(已修复)

这是我目前所拥有的，似乎适用于 AmEx、Visa 和 Mastercard:

Sub PCI_mask_card_numbers()
' Written to mask credit card numbers in excel files in accordance with PCI DSS.
' Highlight the credit card data in the Excel sheet, then run this macro.

Dim strPattern As String: strPattern = "([4][0-9]{3})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})|" & _
"([5][0-9]{3})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})|" & _
"([3][0-9]{2})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})|" & _
"([3][0-9]{3})([^a-zA-Z0-9_]?[0-9]{3})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})|" & _
"([3][0-9]{3})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{3})([^a-zA-Z0-9_]?[0-9]{4})|" & _
"([3][0-9]{3})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{4})([^a-zA-Z0-9_]?[0-9]{3})|" & _
"([3][0-9]{3})([^a-zA-Z0-9_]?[0-9]{6})([^a-zA-Z0-9_]?[0-9]{5})"

' Regex patterns for PANs above are broken into multiple parts (between the brackets)
' As such the when regex matches the first part of a PAN will fit into one of rMatch(k).SubMatches(#) where # is 0, 4, 8, 12, 16, 20 or 24. 
' Visa start with a 4 and is 16 digits long. Typically the data entry pattern is four groups of four digits
' MasterCard start with a 5 and is 16 digits long. Typically the data entry pattern is four groups of four digits
' AmEx start with a 3 and is 15 digits long. Typically the pattern is 4-6-5, but data entry seems inconsistent

    Dim strReplace As String: strReplace = ""
'     Dim regEx As New RegExp  ' if this line is used instead of the next 2, the MS VBS RegEx v5.5 needs to be enabled manually. The next 2 lines seem to do it from within the script
    Dim regEx As Object
    Set regEx = CreateObject("VBScript.RegExp")
    Dim regEx As New RegExp
    Dim strInput As String
    Dim Myrange As Range
    Dim NewPAN As String
    Dim Aproblem As String
    Dim Masked As Long
    Dim Problems As Long
    Dim Total As Long

With regEx
    .Global = True
    .MultiLine = True
    .IgnoreCase = False
    .Pattern = strPattern ' sets the regex pattern to match the pattern above
End With

Set Myrange = Selection

    MsgBox ("The macro will now start masking credit card numbers identified in the selected cells only. If entire columns are selected, each column will take 10-30 seconds to complete. Ditto for Rows.")

For Each cell In Myrange
    Total = Total + 1

    ' Check that the cell is a likely candidate for holding a PAN, not just a long number
    If strPattern <> "" _
    And cell.HasFormula = False _
    And Left(cell.NumberFormat, 1) <> "$" _
    And Mid(cell.NumberFormat, 3, 1) <> "$" Then
'        cell.NumberFormat = "@"
        strInput = cell.Value

        ' Depending on the data matching the regex pattern, fix it
        If regEx.Test(strInput) Then
            Set rMatch = regEx.Execute(strInput)
            For k = 0 To rMatch.Count - 1
                toReplace = rMatch(k).Value

        ' If the regex matched, replace the PAN based on its regex segment
                Select Case 2
                    Case Is < Len(rMatch(k).SubMatches(0))
                        strReplace = rMatch(k).SubMatches(0) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(3))
                        Masked = Masked + 1
                    Case Is < Len(rMatch(k).SubMatches(4))
                        strReplace = rMatch(k).SubMatches(4) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(7))
                        Masked = Masked + 1
                    Case Is < Len(rMatch(k).SubMatches(8))
                        strReplace = rMatch(k).SubMatches(8) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(11))
                        Masked = Masked + 1
                    Case Is < Len(rMatch(k).SubMatches(12))
                        strReplace = rMatch(k).SubMatches(12) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(13))
                        Masked = Masked + 1
                    Case Is < Len(rMatch(k).SubMatches(16))
                        strReplace = rMatch(k).SubMatches(16) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(19))
                        Masked = Masked + 1
                    Case Is < Len(rMatch(k).SubMatches(20))
                        strReplace = rMatch(k).SubMatches(20) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(23))
                        Masked = Masked + 1
                    Case Is < Len(rMatch(k).SubMatches(24))
                        strReplace = rMatch(k).SubMatches(24) & "xxxxxxxx" & Trim(rMatch(k).SubMatches(26))
                        Masked = Masked + 1
                    Case Else
                        Aproblem = cell.Value
                        Problems = Problems + 1
                        ' MsgBox (Aproblem) ' only needed when curios
                End Select
                If cell.Value <> Aproblem Then
                    cell.Value = Replace(strInput, toReplace, strReplace)
                End If

            Next k
        Else
            ' Adds the cell value to a variable to allow the macro to move past the cell
            ' Once the macro is trusted not to loop forever, the message box can be removed
            ' MsgBox ("Problem. Regex fail? Bad data = " & Aproblem)
        End If
    End If
Next cell
' All done, tell the user
    MsgBox ("Cardholder data is now masked" & vbCr & vbCr & "Total cells highlighted (including blanks) = " & Total & vbCr & "Cells masked = " & Masked & vbCr & "Possible problem cells = " & Problems & vbCr & "All other cells were ignored")

End Sub

Answer 1

从假期回来。这是一个简单的 VBA 函数，用于测试 LUHN 算法。参数是一串数字；结果是 bool 值。

它生成一个校验和数字并将该数字与您输入的数字字符串中的数字进行比较。

Option Explicit
Function Luhn(sNum As String) As Boolean
'modulus 10 algorithm for various numbers
Dim X As Long, I As Long, J As Long

For I = Len(sNum) - 1 To 1 Step -2
    X = X + DoubleSumDigits(Mid(sNum, I, 1))
    If I > 1 Then X = X + Mid(sNum, I - 1, 1)
Next I

If Right(sNum, 1) = (X * 9) Mod 10 Then
    Luhn = True
Else
    Luhn = False
End If
End Function

Function DoubleSumDigits(L As Long) As Long
    Dim X As Long
    X = L * 2
    If X > 9 Then X = Val(Left(X, 1)) + Val(Right(X, 1))
    DoubleSumDigits = X
End Function