废话不说，直入正题。
想了一下，Excel文件的保密密码应该是使用弱加密算法直接保存在文件中的，想了两个办法：
1、使用16进制编辑器，查接查看Excel文件本身，看看能不能找到登记密码的位置
2、使用VBA解码
出于程序员的本能，决定先试用VBA的方法。
WPS2017个人版都没VBA功能，首先需要安装VBA支持，我在如下位置下载了VBA安装包：
VBA7.0.1590ForWPS
下载完成后，查了一毒，表示安全。开始安装，安装步骤不再赘述。
安装完成后，用WPS表格打开待解密的Excel文件，通过菜单“开发工具 – 录制新宏”录制一个新宏，直接关闭。
通过菜单“开发工具-宏”打开宏管理器，编辑刚刚录制的新宏，删除全部代码，输入下文中的代码：
Option Explicit
Public Sub AllInternalPasswords()
' Breaks worksheet and workbook structure passwords. Bob McCormick
' probably originator of base code algorithm modified for coverage
' of workbook structure / windows passwords and for multiple passwords
'
' Norman Harker and JE McGimpsey 27-Dec-2002 (Version 1.1)
' Modified 2003-Apr-04 by JEM: All msgs to constants, and
' eliminate one Exit Sub (Version 1.1.1)
' Reveals hashed passwords NOT original passwords
Const DBLSPACE As String = vbNewLine & vbNewLine
Const AUTHORS As String = DBLSPACE & vbNewLine & _
"Adapted from Bob McCormick base code by" & _
"Norman Harker and JE McGimpsey"
Const HEADER As String = "AllInternalPasswords User Message"
Const VERSION As String = DBLSPACE & "Version 1.1.1 2003-Apr-04"
Const REPBACK As String = DBLSPACE & "Please report failure " & _
"to the microsoft.public.excel.programming newsgroup."
Const ALLCLEAR As String = DBLSPACE & "The workbook should " & _
"now be free of all password protection, so make sure you:" & _
DBLSPACE & "SAVE IT NOW!" & DBLSPACE & "and also" & _
DBLSPACE & "BACKUP!, BACKUP!!, BACKUP!!!" & _
DBLSPACE & "Also, remember that the password was " & _
"put there for a reason. Don't stuff up crucial formulas " & _
"or data." & DBLSPACE & "Access and use of some data " & _
"may be an offense. If in doubt, don't."
Const MSGNOPWORDS1 As String = "There were no passwords on " & _
"sheets, or workbook structure or windows." & AUTHORS & VERSION
Const MSGNOPWORDS2 As String = "There was no protection to " & _
"workbook structure or windows." & DBLSPACE & _
"Proceeding to unprotect sheets." & AUTHORS & VERSION
Const MSGTAKETIME As String = "After pressing OK button this " & _
"will take some time." & DBLSPACE & "Amount of time " & _
"depends on how many different passwords, the " & _
"passwords, and your computer's specification." & DBLSPACE & _
"Just be patient! Make me a coffee!" & AUTHORS & VERSION
Const MSGPWORDFOUND1 As String = "You had a Worksheet " & _
"Structure or Windows Password set." & DBLSPACE & _
"The password found was: " & DBLSPACE & "$$" & DBLSPACE & _
"Note it down for potential future use in other workbooks by " & _
"the same person who set this password." & DBLSPACE & _
"Now to check and clear other passwords." & AUTHORS & VERSION
Const MSGPWORDFOUND2 As String = "You had a Worksheet " & _
"password set." & DBLSPACE & "The password found was: " & _
DBLSPACE & "$$" & DBLSPACE & "Note it down for potential " & _
"future use in other workbooks by same person who " & _
"set this password." & DBLSPACE & "Now to check and clear " & _
"other passwords." & AUTHORS & VERSION
Const MSGONLYONE As String = "Only structure / windows " & _
"protected with the password that was just found." & _
ALLCLEAR & AUTHORS & VERSION & REPBACK
Dim w1 As Worksheet, w2 As Worksheet
Dim i As Integer, j As Integer, k As Integer, l As Integer
Dim m As Integer, n As Integer, i1 As Integer, i2 As Integer
Dim i3 As Integer, i4 As Integer, i5 As Integer, i6 As Integer
Dim PWord1 As String
Dim ShTag As Boolean, WinTag As Boolean
Application.ScreenUpdating = False
With ActiveWorkbook
WinTag = .ProtectStructure Or .ProtectWindows
End With
ShTag = False
For Each w1 In Worksheets
ShTag = ShTag Or w1.ProtectContents
Next w1
If Not ShTag And Not WinTag Then
MsgBox MSGNOPWORDS1, vbInformation, HEADER
Exit Sub
End If
MsgBox MSGTAKETIME, vbInformation, HEADER
If Not WinTag Then
MsgBox MSGNOPWORDS2, vbInformation, HEADER
Else
On Error Resume Next
Do 'dummy do loop
For i = 65 To 66: For j = 65 To 66: For k = 65 To 66
For l = 65 To 66: For m = 65 To 66: For i1 = 65 To 66
For i2 = 65 To 66: For i3 = 65 To 66: For i4 = 65 To 66
For i5 = 65 To 66: For i6 = 65 To 66: For n = 32 To 126
With ActiveWorkbook
.Unprotect Chr(i) & Chr(j) & Chr(k) & _
Chr(l) & Chr(m) & Chr(i1) & Chr(i2) & _
Chr(i3) & Chr(i4) & Chr(i5) & Chr(i6) & Chr(n)
If .ProtectStructure = False And _
.ProtectWindows = False Then
PWord1 = Chr(i) & Chr(j) & Chr(k) & Chr(l) & _
Chr(m) & Chr(i1) & Chr(i2) & Chr(i3) & _
Chr(i4) & Chr(i5) & Chr(i6) & Chr(n)
MsgBox Application.Substitute(MSGPWORDFOUND1, _
"$$", PWord1), vbInformation, HEADER
Exit Do 'Bypass all for...nexts
End If
End With
Next: Next: Next: Next: Next: Next
Next: Next: Next: Next: Next: Next
Loop Until True
On Error GoTo 0
End If
If WinTag And Not ShTag Then
MsgBox MSGONLYONE, vbInformation, HEADER
Exit Sub
End If
On Error Resume Next
For Each w1 In Worksheets
'Attempt clearance with PWord1
w1.Unprotect PWord1
Next w1
On Error GoTo 0
ShTag = False
For Each w1 In Worksheets
'Checks for all clear ShTag triggered to 1 if not.
ShTag = ShTag Or w1.ProtectContents
Next w1
If ShTag Then
For Each w1 In Worksheets
With w1
If .ProtectContents Then
On Error Resume Next
Do 'Dummy do loop
For i = 65 To 66: For j = 65 To 66: For k = 65 To 66
For l = 65 To 66: For m = 65 To 66: For i1 = 65 To 66
For i2 = 65 To 66: For i3 = 65 To 66: For i4 = 65 To 66
For i5 = 65 To 66: For i6 = 65 To 66: For n = 32 To 126
.Unprotect Chr(i) & Chr(j) & Chr(k) & _
Chr(l) & Chr(m) & Chr(i1) & Chr(i2) & Chr(i3) & _
Chr(i4) & Chr(i5) & Chr(i6) & Chr(n)
If Not .ProtectContents Then
PWord1 = Chr(i) & Chr(j) & Chr(k) & Chr(l) & _
Chr(m) & Chr(i1) & Chr(i2) & Chr(i3) & _
Chr(i4) & Chr(i5) & Chr(i6) & Chr(n)
MsgBox Application.Substitute(MSGPWORDFOUND2, _
"$$", PWord1), vbInformation, HEADER
'leverage finding Pword by trying on other sheets
For Each w2 In Worksheets
w2.Unprotect PWord1
Next w2
Exit Do 'Bypass all for...nexts
End If
Next: Next: Next: Next: Next: Next
Next: Next: Next: Next: Next: Next
Loop Until True
On Error GoTo 0
End If
End With
Next w1
End If
MsgBox ALLCLEAR & AUTHORS & VERSION & REPBACK, vbInformation, HEADER
End Sub
关闭宏编辑窗口，通过菜单“开发工具-宏”打开宏管理器并运行AllInternalPasswords
此时会弹出对话框，无视并点确定
弹出第二个对话框，继续无视并点确定
神奇的事情发生了，密码出现在第三个对话框中，拿出纸笔抄录一下：
密码成功能回，希望能撤销密码保护的朋友，请自行百度。
