VB 加密解密程序

' 加密解密程序
'
'
'---------------------------------------------------------------------------------------------------------------
Function cipher(stext As String)    '密码加密程序
    Const min_asc = 32
    Const max_asc = 126
    Const num_asc = max_asc - min_asc + 1
    Dim offset As Long
    Dim strlen As Integer
    Dim i As Integer
    Dim ch As Integer
    Dim ptext As String
    offset = 123
    Rnd (-1)
    Randomize (offset)
    strlen = Len(stext)
    For i = 1 To strlen
       ch = Asc(Mid(stext, 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
           ptext = ptext & Chr(ch)
       End If
    Next i
    cipher = ptext
End Function

Function decipher(stext As String)      '密码解密程序
    Const min_asc = 32  '最小ASCII码
    Const max_asc = 126 '最大ASCII码  字符
    Const num_asc = max_asc - min_asc + 1
    Dim offset As Long
    Dim strlen As Integer
    Dim i As Integer
    Dim ch As Integer
    Dim ptext As String
    offset = 123
    Rnd (-1)
    Randomize (offset)
    strlen = Len(stext)
    For i = 1 To strlen
       ch = Asc(Mid(stext, i, 1))  '取字母转变成ASCII码
       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
           End If
           ch = ch + min_asc
           ptext = ptext & Chr(ch)
       End If
    Next i
    decipher = ptext
End Function