It would help to know the environment in which the program will operate. Is it for a web app? a command-line app? an app under X/MS Win*/Mac/etc? These questions will dictate the manner in which a password would be requested.

Also, is there a particular reason you are using this scheme of a 6 number sum? If there is not, you may wish to look at the ability instead of using the crypt() function for instead creating a hashed password, which may be easier to remember than the 6 number set.

If you can provide a little more information as regards the first part, I would suspect there are several who may be able to offer applicable suggestions.