⑶ 为以上对象编写下列代码
为了便于理解,程序中增加了适当的注释。
Option Explicit
Private Sub CmdBrowse_Click()
Dialog.ShowOpen 'show the dialog
Combo1.Text = Dialog.FileName 'set the Filename text box to the selected file
Combo1.Refresh
End Sub
Private Sub CmdQuit_Click()
End
End Sub
Private Sub CmdStartCrack_Click()
Static blnProcessing As Boolean
Dim wd As New Word.Application, xls As New Excel.Application
Dim OpenReturn
Dim strpath, pass, StrTemp, all_char(100) As String
Dim J, K, Password_Start_Long, Password_End_Long, ArrayLen As Integer
Dim I, Temp As Long
ArrayLen = 0 '数组初始化
If ChkDigital.Value = 1 Then
For J = ArrayLen To ArrayLen + 9
all_char(J) = Chr(Asc("0") + J - ArrayLen)
Next J
ArrayLen = ArrayLen + 10
End If
If ChkLowercase.Value = 1 Then
For J = ArrayLen To ArrayLen + 25
all_char(J) = Chr(Asc("a") + J - ArrayLen)
Next J
ArrayLen = ArrayLen + 26
End If
If ChkUppercase.Value = 1 Then
For J = ArrayLen To ArrayLen + 25
all_char(J) = Chr(Asc("A") + J - ArrayLen)
Next J
ArrayLen = ArrayLen + 26
End If
If ChkSpace.Value = 1 Then
all_char(ArrayLen) = " "
ArrayLen = ArrayLen + 1
End If
If ChkBracket.Value = 1 Then
all_char(ArrayLen) = "("
all_char(ArrayLen+1) = ")"
all_char(ArrayLen+2) = "{"
all_char(ArrayLen+3) = "}"
all_char(ArrayLen+4) = "["
all_char(ArrayLen+5) = "]"
ArrayLen = ArrayLen + 6
End If
If ChkOthers.Value = 1 Then
For J = ArrayLen To ArrayLen + 6 '33 to 39
all_char(J) = Chr(33 + J - ArrayLen)
Next
ArrayLen = ArrayLen + 7
For J = ArrayLen To ArrayLen + 5 '42 to 47
all_char(J) = Chr(42 + J - ArrayLen)
Next J
ArrayLen = ArrayLen + 6
For J = ArrayLen To ArrayLen + 6 '58 to 64
all_char(J) = Chr(58 + J - ArrayLen)
Next J
ArrayLen = ArrayLen + 7
all_char(ArrayLen) = Chr(92)
ArrayLen = ArrayLen + 1
For J = ArrayLen To ArrayLen + 2 '94 to 96
all_char(J) = Chr(94 + J - ArrayLen)
Next J
ArrayLen = ArrayLen + 3
all_char(ArrayLen) = Chr(124)
all_char(ArrayLen+1) = Chr(126)
ArrayLen = ArrayLen + 2
End If
If ArrayLen = 0 Then
MsgBox "错误:没有选择'密码使用的字符'", , "请选择密码使用的字符范围..."
Exit Sub
End If
If blnProcessing Then
If MsgBox("真的要中断解密过程吗?", vbYesNo, "用户中断任务") = vbYes Then blnProcessing = False
Else
CmdStartCrack.Caption = "中断破解"
blnProcessing = True
strpath = Combo1.Text
If strpath = "" Then
MsgBox "错误:没有选择'需要解密的文件'", , "请选择需要解密的文件..."
Exit Sub
End If
strpath = Trim(strpath)
Password_Start_Long = Val(txtPasswordStartLong.Text)
Password_End_Long = Val(txtPasswordEndLong.Text)
If Password_Start_Long > Password_End_Long Then
Password_Start_Long = Val(txtPasswordEndLong.Text)
Password_End_Long = Val(txtPasswordStartLong.Text)
End If
Label1.Caption = "破解进度:"
Label1.Refresh
On Error Resume Next
If UCase(Right(strpath, 3)) = "XLS" Then
For K = Password_Start_Long To Password_End_Long '破解excel开始
For I = 0 To ArrayLen ^ K - 1
pass = ""
Temp = I
For J = 1 To K - 1
Temp = Temp \ ArrayLe
pass = all_char(Temp Mod ArrayLen) + pass
Next J
pass = pass + all_char(I Mod ArrayLen)
Set OpenReturn = xls.Workbooks.Open(FileName:=strpath, Password:=pass)
Text1.Text = pass '显示破解进度
Text1.Refresh
If Err.Number <> 0 Then '如果解密成功,打开文档,显示密码,退出过程
Err.Clear
Else
Label1.Caption = "文档密码:"
Text1.Text = pass
Me.Refresh
xls.Visible = True
CmdStartCrack.MousePointer = 0
CmdStartCrack.Caption = "开始破解"
blnProcessing = False
Set xls = Nothing
Exit Sub
End If
DoEvents
If Not blnProcessing Then Exit For
Next I
If Not blnProcessing Then Exit For
Next K
xls.Quit
Set xls = Nothing
Else
For K = Password_Start_Long To Password_End_Long '破解word开始
For I = 0 To ArrayLen ^ K - 1
pass = ""
Temp = I
For J = 1 To K -
Temp = Temp \ ArrayLen
pass = all_char(Temp Mod ArrayLen) + pass
Next J
pass = pass + all_char(I Mod ArrayLen)
OpenReturn = wd.Documents.Open(FileName:=strpath, passworddocument:=pass)
Text1.Text = pass '显示破解进度
Text1.Refresh
If Err.Number <> 0 Then '如果解密成功,打开文档,显示密码,退出过程
Err.Clear
Else
'MsgBox "word password"
Label1.Caption = "文档密码:"
Text1.Text = pass
Me.Refresh
wd.Visible = True
CmdStartCrack.MousePointer = 0
CmdStartCrack.Caption = "开始破解"
blnProcessing = False
Set wd = Nothing
Exit Sub
End If
DoEvents
If Not blnProcessing Then Exit For
Next I
If Not blnProcessing Then Exit For
Next K
wd.Quit
Set wd = Nothing
End If
CmdStartCrack.Caption = "开始破解"
If blnProcessing Then MsgBox "没有找到密码,可能是密码位数不对!", , "提示信息..."
blnProcessing = False
End Sub
3. 时间复杂度分析
一个算法的时间复杂度,是指该算法的时间耗费,是该算法所求解问题规模n的函数。根据前面讲的实现原理,我们知道,破解算法的时间耗费主要集中在尝试打开OFFICE文档上,因此,当我们假设破解一个N位字符串密码,且选定密码字符范围的总字符数为ArrayLen时,该算法的时间复杂度是O(ArrayLen^N)。即,当N确定后,该算法的时间复杂度是N次方阶;当ArrayLen确定后,该算法的时间复杂度是指数阶。都是高数量级的时间复杂度。
4. 说明
穷举法解密对系统资源的占用是十分惊人的,在解密的过程中最好不要运行其他应用程序。如果安装有瑞星等杀毒软件,应将杀毒软件的“office安全助手”去掉,以便加快程序的运行速度。
该程序在WinXP+OfficeXP+VB6.0环境下测试通过,笔者随便测试了一个5位数字密码,在P4机器上,8分钟左右即可解开口令。参考文献:
[1] 王建华 译. Visual Basic 6 开发人员指南. 北京:机械工业出版社,1999