I found a light solution but i dont know if it have a good reliability. can put any data on a special personal folder and then hide it (lock without password) or unhide it (unlock with a password) with a small DOS code. it seems to work properly. this solution is in this link: http://operating-systems.wonderhowto.com/how-to/lock-folder-without-any-software-with-password-0150639/ i translated it to vfp and compiled a crypted exe (13 ko). Give me your advice on the link above please.