Thank you very much for your replies.. So I mst now encrypt the HD serial.. but what which kind of encryption must I use.. I mean can I user MD5 or for example : Serial No. + 5353+fgedf345+534 soe thing loke that? that will give me the Serial No. with more values added to it.. and remmember that this value will be added to mySQL Database at my server.. and every time the client wants to login to his account.. the login page will verify that serial.. so do you guess that if I used any kind of encryption will work? or I must use MD5 (Hashing System)?

Waiting your replies..

Regards,