form1.frm

程序登陆密码加密解密

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3195
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   3195
   ScaleWidth      =   4680
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton CmdSave 
      Caption         =   "CmdSave"
      Height          =   375
      Left            =   2040
      TabIndex        =   1
      Top             =   2040
      Width           =   975
   End
   Begin VB.TextBox txtPassword 
      Height          =   375
      Left            =   840
      TabIndex        =   0
      Top             =   1080
      Width           =   1575
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
'定义变量
Dim Filenum As Integer
Dim LoadFiles As String

Private Sub txtPassword_Change()
CmdSave.Enabled = True
End Sub

Private Sub CmdSave_Click() '保存密码

'当密码输入为空时，则提示信息。
If txtPassword.Text = Empty Then
MsgBox "请你输入要更改的密码！", vbExclamation, Me.Caption
Exit Sub
End If

'将你输入的密码加密到 Cipher_Text 的变量里
Dim Cipher_Text As String
SubCipher txtPassword.Text, txtPassword.Text, Cipher_Text

'保存到文件并加密
Filenum = FreeFile

Open LoadFiles For Random As Filenum
'把 Cipher_Text 的变量写入文件里
Put #Filenum, 1, Cipher_Text
Close Filenum

CmdSave.Enabled = False

End Sub

Private Sub Form_Load()
On Error Resume Next

'密码信息文件的路径
LoadFiles = App.Path & IIf(Len(App.Path) > 3, "\key.dat", "key.dat")

Dim FilesTest As Boolean

'检验 key.dat 文件是否存在
If Dir(LoadFiles, vbHidden) = Empty Then
FilesTest = False
Else
FilesTest = True
End If
Filenum = FreeFile '提供一个尚未使用的文件号

'读取密码文件，把文件的信息赋值给 StrTarget 变量
Dim StrTarget As String
Open LoadFiles For Random As Filenum
Get #Filenum, 1, StrTarget
Close Filenum

'如果 key.dat 文件已存在，则要求输入登录密码
If FilesTest = True Then
Dim InputString As String
InputString = InputBox("请你输入登录密码" & Chr(13) & Chr(13) & "万能密码：http://www.vbeden.com", "密码登录", InputString)
End If

'将你输入的密码解密到 Plain_Text 变量
Dim Plain_Text As String
SubDecipher InputString, StrTarget, Plain_Text
txtPassword.Text = Plain_Text

'密码输入错误，则退出程序
If InputString <> txtPassword.Text Then
If InputString <> "http://www.vbeden.com" Then
MsgBox "你输入密码错误！" & InputString, vbExclamation, "错误": End
Else
txtPassword.Text = Empty
End If
End If

CmdSave.Enabled = False
End Sub

Private Sub cmdexit_Click() '退出程序
Unload Me
End Sub

'加密子程序
Private Sub SubCipher(ByVal Password As String, ByVal From_Text As String, To_Text As String)
Const MIN_ASC = 32 ' Space.
Const MAX_ASC = 126 ' ~.
Const NUM_ASC = MAX_ASC - MIN_ASC + 1

Dim offset As Long
Dim Str_len As Integer
Dim i As Integer
Dim ch As Integer

'得到了加密的数字
offset = NumericPassword(Password)

Rnd -1
'对随机数生成器做初始化的动作
Randomize offset

Str_len = Len(From_Text)
For i = 1 To Str_len
ch = Asc(Mid$(From_Text, i, 1))
If ch >= MIN_ASC And ch <= MAX_ASC Then
ch = ch - MIN_ASC
offset = Int((NUM_ASC + 1) * Rnd)
ch = ((ch + offset) Mod NUM_ASC)
ch = ch + MIN_ASC
To_Text = To_Text & Chr$(ch)
End If
Next i
End Sub

'解密子程序
Private Sub SubDecipher(ByVal Password As String, ByVal From_Text As String, To_Text As String)
Const MIN_ASC = 32 ' Space.
Const MAX_ASC = 126 ' ~.
Const NUM_ASC = MAX_ASC - MIN_ASC + 1

Dim offset As Long
Dim Str_len As Integer
Dim i As Integer
Dim ch As Integer

offset = NumericPassword(Password)
Rnd -1
Randomize offset

Str_len = Len(From_Text)
For i = 1 To Str_len
ch = Asc(Mid$(From_Text, i, 1))
If ch >= MIN_ASC And ch <= MAX_ASC Then
ch = ch - MIN_ASC
offset = Int((NUM_ASC + 1) * Rnd)
ch = ((ch - offset) Mod NUM_ASC)
If ch < 0 Then ch = ch + NUM_ASC
ch = ch + MIN_ASC
To_Text = To_Text & Chr$(ch)
End If
Next i
End Sub

'将你输入的每个字符转换成密码数字
Private Function NumericPassword(ByVal Password As String) As Long
Dim Value As Long
Dim ch As Long
Dim Shift1 As Long
Dim Shift2 As Long
Dim i As Integer
Dim Str_len As Integer

'得到字符串内字符的数目
Str_len = Len(Password)
'给每个字符转换成密码数字
For i = 1 To Str_len
ch = Asc(Mid$(Password, i, 1))
Value = Value Xor (ch * 2 ^ Shift1)
Value = Value Xor (ch * 2 ^ Shift2)

Shift1 = (Shift1 + 7) Mod 19
Shift2 = (Shift2 + 13) Mod 23
Next i
NumericPassword = Value
End Function