Encrypt and decrypt member registration password

You can write your own encryption and decryption program. Reversible.
It is usually encrypted with MD5. The data written by the database is encrypted.
However, this method of encryption is irreversible.

Write an encryption, decryption program, very simple:)

<% @Language = "JavaScript"%>
<%
var pwd = "Gray bean";
function Encrypt (str)
{
var newstr = "";
str = Escape (str);
var len = str.length;

for (Var i=0;i<len;i++)
{
Tmpstr = Str.substr (i,1)
Newstr + + string.fromcharcode (tmpstr.charcodeat (0) +i);
}
return newstr;
}
function Uncrypt (str)
{
var newstr = "";
var len = str.length;
for (Var i=0;i<len;i++)
{
Tmpstr = Str.substr (i,1);
Newstr + + string.fromcharcode (tmpstr.charcodeat (0)-i);
}
return unescape (NEWSTR);
}
Response.Write ("Before Encryption:" +uncrypt (Encrypt (PWD)) + "<br/>")
Response.Write ("After decryption:" +encrypt (PWD))

%>