现在有些软件都设置密码登录，启动软件时要求使用者输入有效的密码。 其实密码就是对明文文本进行一一对应的变换，使这变成不可识别的密码文本，让非法使用者不能识别。 本程序是通过，输入登录密码，然后把用户密码加密保存到文本里。 首先，建立一个标准EXE工程，在窗体上放置一个TextBox控件，名称为txtPassword，PasswordChar属性为"*"。 再放置两个CommandButton控件，第一个的名称为CmdSave，Caption属性为"保存密码(&S)"，另一个的名称为CmdExit，Caption属性为"退出(&Q)"。 主程序原代码如下： Option Explicit定义变量Dim Filenum As IntegerDim LoadFiles As String Private Sub txtPassword_Change() CmdSave.Enabled = TrueEnd 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) $#@62; 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, 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://vbboshi.126.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 $#@60;$#@62; txtPassword.Text Then If InputString $#@60;$#@62; "http://vbboshi.126.com" Then MsgBox "你输入密码错误！", vbExclamation, "错误": End Else txtPassword.Text = Empty End If End If CmdSave.Enabled = FalseEnd Sub Private Sub cmdexit_Click() 退出程序 Unload MeEnd 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 $#@62;= MIN_ASC And ch $#@60;= MAX_ASC Then ch = ch - MIN_ASC offset = Int((NUM_ASC + 1) * Rnd) ch = ((ch + offset) Mod NUM_ASC) ch = ch + MIN_ASC To_Text = To_Text & Chr$(ch) End If Next iEnd 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 $#@62;= MIN_ASC And ch $#@60;= MAX_ASC Then ch = ch - MIN_ASC offset = Int((NUM_ASC + 1) * Rnd) ch = ((ch - offset) Mod NUM_ASC) If ch $#@60; 0 Then ch = ch + NUM_ASC ch = ch + MIN_ASC To_Text = To_Text & Chr$(ch) End If Next iEnd 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 = ValueEnd Function
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