How to encrypt files securely (one method)?

This provides a small procedure for file encryption, for your reference.
<%@ 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 "Encrypted:" & 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)