How to encrypt files is the safest? _ Programming 10000 Q

<%@ Language = vbscript%>
<%

Response.Expires = 0

p = "ABCDEFG"
Set testpwd = New Cpassword
TESTPWD.ENPWD P
Testpwd.unpwd testpwd.showpwd (True)

K = Testpwd.showpwd (True)
L = testpwd.showpwd (False)
Set testpwd = Nothing

With Response
. Write "Original: "& P &" <br> "
. Write "After encryption: "& K &" <br> "
. Write "After decryption: "& L &" <br> "
End With


Class Cpassword
Private cenpwd,cunpwd

Private Function My_hex (My_hex_source)
My_hex = Hex (My_hex_source)
If Len (My_hex) = 1 Then
My_hex = "0" & My_hex
End If
End Function

Private Function My_unhex (My_unhex_source)
If Len (My_unhex_source) = 2 Then
Temp_value = My_hexreplace (left (my_unhex_source,1))
End If
My_unhex = Temp_value * + my_hexreplace (right (my_unhex_source,1))
End Function

Private Function my_hexreplace (My_hexreplace_source)
If ASC (my_hexreplace_source) > Then
My_hexreplace = ASC (UCase (My_hexreplace_source))-55
Else
My_hexreplace = ASC (my_hexreplace_source)-48
End If
End Function

Public Property Get Showpwd (EnP)

'Output.
If EnP Then
Showpwd = Cenpwd
Else
Showpwd = Cunpwd
End If
End Property

Sub enpwd (Enpwd_source)
If Enpwd_source = "" Then
CENPWD = 0
Exit Sub
Else
Randomize
Key = Rnd * 256
While Key = 0
Key = Rnd * 256
Wend
For I=1 to Len (Enpwd_source)
temp_string = Key Xor Asc (Mid (enpwd_source,i,1))
CRC = CRC + Temp_string
Cenpwd = cenpwd + My_hex (temp_string)
Next
Cenpwd = My_hex (Key) + strreverse (cenpwd) + my_hex (CRC Mod 256)
End If
End Sub

Sub unpwd (Unpwd_source)
If Len (Unpwd_source) < 6 Or len (unpwd_source) Mod 2 = 1 Then
CUNPWD = 0
Exit Sub
End If
Old_key = My_unhex (left (unpwd_source,2))
OLD_CRC = My_unhex (Right (unpwd_source,2))
old_string = StrReverse (Mid (Unpwd_source,3,len (Unpwd_source)-4))
For I=1 to Len (old_string)-1 Step 2
Temp_value = My_unhex (Mid (old_string,i,2))
Crc_temp = crc_temp + temp_value
temp_string = temp_string + Chr (temp_value Xor Old_key)
Next
If OLD_CRC <> (crc_temp Mod 256) Then
CUNPWD = 403
Exit Sub
End If
Cunpwd = temp_string
End Sub
End Class

%>