只有一个方法，使用的时候很简单，比如要加密就这样EnDeCode("Data",1234)
解密的时候还是这样EnDeCode("Data",1234)。很简单的。
代码：
Public Class Encryption
    Public Function EnDeCode(ByVal Source As String, ByVal Key As Integer) As String
        Dim X As Single
        Dim intCharNumber As Integer
        Dim shtRADInt As Short
        Dim strChar As String
        Dim strTmp As String
        If Key < 0 Then
            Key = Key * (-1)
        End If
        X = Rnd(-Key)
        Dim i As Integer
        For i = 1 To Len(Source) Step 1
            strChar = Mid(Source, i, 1)
            intCharNumber = Asc(strChar)
WhileEncode:
            shtRADInt = Int(127 * Rnd())
            If shtRADInt < 30 Or shtRADInt > 100 Then GoTo WhileEncode
            intCharNumber = intCharNumber Xor shtRADInt
            strTmp = strTmp & Chr(intCharNumber)
        Next i
        EnDeCode = strTmp
        Exit Function
    End Function
End Class