VB6 加密解密字符串

Public Function EnCodeStr(ByVal password As String) As String
    Dim il_bit, il_x, il_y, il_z, il_len, i               As Long
    Dim is_out     As String
    il_len = Len(password)
    il_x = 0
    il_y = 0
    is_out = ""
    For i = 1 To il_len
            il_bit = AscW(Mid(password, i, 1))
            il_y = (il_bit * 13 Mod 256) + il_x
            is_out = is_out & ChrW(Fix(il_y))
            il_x = il_bit * 13 / 256
    Next
    is_out = is_out & ChrW(Fix(il_x))
    password = is_out
    il_len = Len(password)
    il_x = 0
    il_y = 0
    is_out = ""
    For i = 1 To il_len
            il_bit = AscW(Mid(password, i, 1))
            il_y = il_bit / 16 + 64
            is_out = is_out & ChrW(Fix(il_y))
            il_y = (il_bit Mod 16) + 64
            is_out = is_out & ChrW(Fix(il_y))
    Next
    EnCodeStr = is_out
End Function

Public Function DeCodeStr(ByVal password As String) As String
    Dim is_out     As String
    Dim il_x, il_y, il_len, i, il_bit             As Long

    il_len = Len(password)
    il_x = 0
    il_y = 0
    is_out = ""
    For i = 1 To il_len Step 2
            il_bit = AscW(Mid(password, i, 1))
            il_y = (il_bit - 64) * 16
            il_y = il_y + AscW(Mid(password, i + 1, 1)) - 64
            is_out = is_out & ChrW(il_y)
    Next

    il_x = 0
    il_y = 0
    password = is_out
    is_out = ""

    il_len = Len(password)
    il_x = AscW(Mid(password, il_len, 1))

    For i = (il_len - 1) To 1 Step -1
            il_y = il_x * 256 + AscW(Mid(password, i, 1))
            il_x = il_y Mod 13
            is_out = ChrW(Fix(il_y / 13)) & is_out
    Next
    DeCodeStr = is_out
End Function