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
文章整理：西部数码--专业提供域名注册、虚拟主机服务
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